Evidence of a Correction To the Speed of Light

KentuckyFC writes: In the early hours of the morning on 24 February 1987, a neutrino detector deep beneath Mont Blanc in northern Italy picked up a sudden burst of neutrinos. Three hours later, neutrino detectors at two other locations picked up a second burst. These turned out to have been produced by the collapse of the core of a star in the Large Magellanic Cloud that orbits our galaxy. And sure enough, some 4.7 hours after this, astronomers noticed the tell-tale brightening of a blue supergiant in that region, as it became a supernova, now known as SN1987a. But why the delay of 7.7 hours from the first burst of neutrinos to the arrival of the photons? Astrophysicists soon realized that since neutrinos rarely interact with ordinary matter, they can escape from the star's core immediately. By contrast, photons have to diffuse through the star, a process that would have delayed them by about 3 hours. That accounts for some of the delay but what of the rest? Now one physicist has the answer: the speed of light through space requires a correction. As a photon travels through space, there is a finite chance that it will form an electron-positron pair. This pair exists for only a brief period of time and then goes on to recombine creating another photon which continues along the same path. This is a well-known process called vacuum polarization. The new idea is that the gravitational potential of the Milky Way must influence the electron-positron pair because they have mass. This changes the energy of the virtual electron-positron pair, which in turn produces a small change in the energy and speed of the photon. And since the analogous effect on neutrinos is negligible, light will travel more slowly than them through a gravitational potential. According to the new calculations which combine quantum electrodynamics with general relativity, the change in speed accounts more or less exactly for the mysterious time difference.

Comments

Which means

[Anonymous Coward]

Einstein was WRONG!

E = mc^3 !!

Which by the way, still works!

Re:Which means

[VernonNemitz]

There seems to me to be a slight error in the original article. Neutrinos have been determined to possess mass. It is only a slight amount of mass, but it precludes them from being able to travel at exactly the speed of light. How close to light-speed do they normally travel? I can't say. But it is reasonable to think that the distance from Supernova 1987A to Earth should have led to a slightly later arrival time, for neutrinos, than if they had actually traveled at light-speed.

The preceding relates to another thing, the quantum-mechanical mechanism for interfering with the actual speed of light. Those pairs of virtual particles that form also have mass. That means, while they temporarily exist, they also cannot be traveling at exactly light-speed; they have to be traveling slightly slower.

Re:Which means

[i_ate_god]

well no

E = m(c*1.2481005830886023468204621)^2

Re:Which means

[Anonymous Coward]

If it really was a ~24% difference then pretty much every physicist should be called incompetent.

Re:Which means

[Anonymous Coward]

energy = matter is the gist of it. the speed of light was thrown in, and squared, only for effect. as in, the enery in matter is HUGE! every school boy - outside america - knows this.

Re:Which means

[Anonymous Coward]

There seems to me to be a slight error in the original article. Neutrinos have been determined to possess mass. It is only a slight amount of mass, but it precludes them from being able to travel at exactly the speed of light.

This line of thought has always bugged me.

Neutrinos assumed to have rest mass because it is assumed time must pass for flavour oscillation to occur... yet it must be very very very small or else we would be wrong... and oh by the way photons can momentarily turn into other shit on their journeys yet somehow neutrinos can't. Assumptions piled atop assumptions.

I realize all of science is based on combinations of measurement and theory but the cherry picking of properties and lack of observational evidence showing neutrinos propagate any faster or slower than light is disheartening.

Re:Which means

[Anonymous Coward]

and oh by the way photons can momentarily turn into other shit on their journeys yet somehow neutrinos can't

Yet that ability to turn into other things is already factored into the speed of light, just as it is factored into other measurements. Quantum field theory that discusses such processes is quite aware of the idea we only measure the final result and not the individual pieces... then goes on to make predictions to 15 digits of precision. And neutrinos can turn into other stuff, as can another other particle, but it is more limited by not being a charged particle and not interacting with electromagnetism directly.

Re:Which means

[Anonymous Coward]

There seems to me to be a slight error in the original article. Neutrinos have been determined to possess mass. It is only a slight amount of mass, but it precludes them from being able to travel at exactly the speed of light. How close to light-speed do they normally travel? I can't say. But it is reasonable to think that the distance from Supernova 1987A to Earth should have led to a slightly later arrival time, for neutrinos, than if they had actually traveled at light-speed.

The preceding relates to another thing, the quantum-mechanical mechanism for interfering with the actual speed of light. Those pairs of virtual particles that form also have mass. That means, while they temporarily exist, they also cannot be traveling at exactly light-speed; they have to be traveling slightly slower.

False. Neutrinos can go faster than the speed of light. It's a common mistake by laymen that relativity says that nothing can travel at or above the speed of light. In fact, relativity only says that it is impossible to accelerate to or above the speed of light. It says nothing about particles that already travel at or faster than light speed.

Re:Which means

[Khashishi]

I think you are confusing neutrinos, which have been known for a while, with tachyons, which are speculative and haven't been detected. Neutrinos don't move faster than light.

Re:Which means

[Anonymous Coward]

you can find the speed of light with 1), a microwave, 2) a chocolate bar, and 3) a ruler
with much better precision than 25%

Re:Which means

[Anonymous Coward]

Maybe. we are talking about a voyage of 163,000 light-years. During that time each photon interacts with the gravity well of a zillion start and galaxies. Thus, their path is not a straight line, whilst the Neutrinos move along oblivious of their surroundings and just listen to the iPods. All this time the expansion of space is a factor. Whilst it is a wee factor, it must be considered since eventually it adds up and the edges of the universe are moving away at about the speed of light. Thus, the size of the universe itself is in question since cannot see further than about 14 Billion light years. But I digress. Their path may be changed by virtual activity, by gravitational Brownian movement, relativistic effects due to temporal shifting in gravity wells, or just plain interaction with the vacuum energy of space. Besides, there is a tiny loss as items move from one Planck space to another. I feel it late in the evenings.

Re:Which means

[Anonymous Coward]

You forgot #4: either the stick on the microwave or outside knowledge of the frequency of a typical microwave oven. Measuring the frequency instead of as a given takes a bit more effort (alternatively, you can measure the frequency of a microwave oven using a chocolate bar, ruler, and the value of c...).

Re:Which means

[psyclone]

If you reverse the polarity of the neutrino beam, you might be able to detect the tachyon pulse that's out of phase with normal matter!

Re:Which means

[Anonymous Coward]

the stick on the microwave

The sticker on the microwave, as older microwaves used to list their frequency to some rough precision on them.

Re:Which means

[GPierce]

If you chose your units of measure correctly, c^2 = c^3 = c^n = 1, and under this choice. E=m.

Re:Which means

[sexconker]

Just wanted to post and say that you're completely and utterly incorrect.
If something could travel faster than the speed of light all of causality would be broken.

Re:Which means

[Anonymous Coward]

Slow down there! That won't work unless you first realign the flux compensator in the neutrino emission arrays to match the carrier wavefront patterns of the tachyon capacitor coils.
Then it will be just like catching a butterfly with a net!

Re:Which means

[Anonymous Coward]

He's not confusing anything, you are. He said anything with mass cannot move at the speed of light. (For large values of light). In any case, It may be time to rewrite all the science books again.

Re:Which means

[dryeo]

That is only true if the faster then light particle carries information. The way I heard it (and I don't remember where and whether it was much more then speculation) was that photons average the speed of light so they might go a bit faster, then a bit slower then c. There is also phenomena such as quantum entanglement that clearly show the speed of light being broken or bypassed with no information being transmitted faster then light. There are other quantum effects that also seem like they may be instant, unluckily it is really hard to measure speed at trillionths of an inch.

Re:Which means

[ihtoit]

they generally operate at 2.4GHz, which is the resonant frequency of water. Yes, a leaky microwave oven will interfere with wifi and bluetooth.

Re:Which means

[Anonymous Coward]

They operate at 2.4 GHz because that frequency was set aside for use in industrial and other non-communication uses, which is also how it ended up used for wifi, "We don't care if you dump communication on this band without a license, just remember you can't ask industrial sources from stopping what they are doing." It isn't a particular resonance of water, just a matter of convenience and engineering ease. Commercial and industrial microwave ovens tend to operate at 900 MHz, because it is easier to make more efficient, higher power sources at that frequency, while 2.4 GHz is harder but produces smaller units, and the next ISM band at 5.8 GHz is a bit too hard to be economical. The efficiency of heating clean water actually increases at higher frequencies up into the 10s of GHz, although water with dissolved salts and temperature dependence of dielectric properties of water smear that out a lot so it doesn't matter too much what frequency you use over more than an order of magnitude.

Re:Which means

[fiziko]

What lack of observational evidence? Neutrinos do not produce Cerenkov radiation (light booms, caused by traveling faster than light) in a vacuum, but they do in a fluid such as they do at neutrino detectors such as this one. This indicates that they travel faster than light when light is barely slowed down, but not when light is in a vacuum. Hence, the evidence indicates that neutrinos travel close to, but not at the speed of light. How close? We haven't measured that yet (to my knowledge) but we can: detect them in materials with refractive index progressively closer to 1.00 until the light booms stop. That's when the speeds match.

Re:Which means

[Anonymous Coward]

It's not exactly 'the' resonant frequency of water. It's one of the frequency where water molecules in liquid form rotate nicely. The lowest resonant frequency for water in liquid for is at about 22.2GHz. They chose 2.4GHz because it was cheap to produce magnetrons at those respective sizes and because it was an economical compromise between penetration depth and absorption of the radiation. Lower frequencies, like in industrial microwave ovens, mean better penetration depth but lower absorption, which means that you can heat up much larger food portions but that it will also take longer. You'll probably know these problems from your own microwave oven. When you put a considerable amount of (solid) food from the fridge into a deep bowl and then "microwave" it for a few minutes, you can burn your tongue when you touch the top layers but at the bottom it will most likely be still cold.
To find out if your microwave oven is leaky: Unplug it, put a cellphone with active bluetooth in it, close the door and then try to access the cellphones bluetooth from another bluetooth device.

Re:Which means

[Anonymous Coward]

When an European team erroneously announced detection of faster-than-light neutrinos in 2011, most physicists were deeply skeptical, but stopped short of saying it was impossible. This is because, while no credible theory predicts the existence of a FTL particle, no credible theory expressly prohibits one either. ("Causality"? That's just your common sense telling you there is causality in the world. Nothing in the laws of physics as we know it mandates causality.) Until we understand why FTL particles can never be created, physicists will not be comfortable laughing off data like that.

Re:Which means

[Anonymous Coward]

There are a bunch of very credible theories built on causality as a component principle (pretty much anything connected to relativity, including things like quantum field theory), that while allowing for faster than light particles, would not allow for them to interact with slower than light particles. Scientists weren't saying it was impossible because of a lack of credible theories, but because regardless of how credible any theory is there is a chance it is wrong and ultimately some carefully taken data will illustrate that.

Re:Which means

[MindCrusher]

No particle travel faster than the speed of light in vacuum. Light travels slower in certain materials to the point it is almost completely stopped (several experiments are studying such events). Cerenkov radiation occurs when a charged particle exceeds the speed of light in a certain material (e.g. water). See: http://en.wikipedia.org/wiki/C...

Re:Which means

[Anonymous Coward]

It's not exactly 'the' resonant frequency of water. It's one of the frequency where water molecules in liquid form rotate nicely. The lowest resonant frequency for water in liquid for is at about 22.2GHz.

It is neither "the resonant frequency" nor a resonance of any sort. You won't see rotational peaks in liquid water, and won't see any narrow peaks in the absorption of water until you get into the 10s of THz and hit vibrational peaks. The hydrogen bonding in liquid water gives too much friction to see clear rotation peaks and rotation states, and instead you at best have a long relaxation time compared to water vapor. You can get an optimal frequency for a given temperature, but it is more like the optimal rpm of an engine, where in one direction on the scale there is too much friction and on the other there is under-utilization (and an order of magnitude slower than the relaxation time scale).

Re:Which means

[Parlyne]

The necessity of mass is not an assumption and it has nothing to do with the passage of time. In short, oscillation can only occur if the neutrinos are produced in states that are a mixture of multiple physical states. Generically, the physical states are the ones that have well-defined values of mass. But, if all of the neutrinos have the same mass (whether it's 0 or not), then any mixture of the states is equally physical; so, the flavor states in which neutrinos are produced are, themselves, physical states, meaning that there's no mixing. So, it's not that they need to have mass, per se, it's that their masses need to differ from each other, meaning that at least two of the three states have to have non-zero mass.

Also, neutrinos can turn into other things in flight. For instance, an electron neutrino can briefly turn into an electron and a W^+ (well, in the same sense that a photon can "turn into" and electron and a positron, which isn't really quite a correct description, anyway). The thing is, because the mass of the W is so high, this sort of fluctuation is much rarer and lasts for a much shorter time. (This is where the statement about the weak force making these oscillations less relevant comes in.)

But, the problem with evidence for deviation from the speed of light is that, to not be an effect too small to measure, we would need to be looking at extremely low energy neutrinos. But, we don't actually have any ways to detect neutrinos with such small energies.

All that said, I actually have some issues with the idea presented. I haven't gone through the paper in detail; but, it seems like it's probably generating a violation of relativity by not actually working in a fully relativistic framework in the first place. It looks like the treatment of gravity may be too classical; but, that's just from a cursory look.

Re:Which means

[Parlyne]

It's not actually the neutrinos that produce the Cerenkov radiation in detectors. That only happens when a neutrino interacts in a way that either produces a high energy charged particle or gives a great deal of energy to a charged particle that is already present. In either case the need for an interaction with matter that's present in the detector means that such interactions will be very rare in vacuo; and, given how special the condition we need to actually see these events in detectors, it's unlikely that we would detect them in vacuo even if they happened. Further, since the Cerenkov radiation has to do with the speed of the charged particle, its presence or lack thereof wouldn't actually tell us about the mass of the neutrino.

Re:Which means

[Mr Z]

Also, there's a semantic looseness as well that bothers me. The proposed solution doesn't really require changing the speed of light in a vacuum. Rather, it points out that photons will undergo certain interactions which mean that light as a bulk phenomenon will appear to go slower than the maximum speed light can travel in a vacuum because of those other interactions.

When computing relativistic effects, such as Lorenz contractions, etc., the upper speed (not including all those interactions) still remains the limit, at least as I understand it.

Re:Which means

[blueg3]

Relativity only actually requires that particles with mass stay on one side of the speed of light: strictly below or strictly above. The "strictly above" particles, which are entirely theoretical, are called tachyons.

Re:Which means

[sexconker]

If FTL travel was possible, then causality would have already been broken, and we would see the effects of it all the fucking time.

Re:Which means

[sexconker]

That is only true if the faster then light particle carries information. The way I heard it (and I don't remember where and whether it was much more then speculation) was that photons average the speed of light so they might go a bit faster, then a bit slower then c. There is also phenomena such as quantum entanglement that clearly show the speed of light being broken or bypassed with no information being transmitted faster then light. There are other quantum effects that also seem like they may be instant, unluckily it is really hard to measure speed at trillionths of an inch.

If the particle exists, then it carries information. A particle can't exist without interacting with the Universe in some way, and those interactions require information.

Re:Which means

[Parlyne]

Neutrinos are affected by gravity. Everything is. And, so far as general relativity is concerned, the paths that objects travel along under the influence of gravity (and nothing else) ARE the closest thing to straight line paths that actually exist.

Re:Which means

[Anonymous Coward]

Plenty of interactions happen between particles without exchange of information, which is how you can manipulate photons and electrons in quantum mechanics experiments using high quality optics without perturbing their state. There is the whole concept of weak measurements too where you can have interactions with very small exchanges of information.

In particular, if you have one half of an entangled pair, there is no measurement in isolation you can make that would tell you that you have part of an entangled pair. There is nothing a person could do to the other half that would convey information, as your measurements will always produce the same distribution of results. You can only see the effects of entanglement when you classically communicate with the person that has the other half, and see a correlation in measurements, or a correlation with actions that the other person performed.

Re:Which means

[Khashishi]

Theoretical is too strong a word to describe tachyons. Better to call them science fiction. Tachyons violate causality, and create some kinds of vacuum instability. They don't exist.

Re:Which means

[budgenator]

Neutrinos do not produce Cerenkov radiation (light booms, caused by traveling faster than light) in a vacuum, but they do in a fluid such as they do at neutrino detectors such as this one.

Cerenkov radiation when a particle travels faster than light in a given medium, such as a neutron can travel faster through water than light can but still travels slower than the speed of light in a vacuum.

If that isn't confusing, consider the article says light that always has to travel at the speed of light, can't travel at the speed of light because light isn't always light!

Re:Which means

[sillybilly]

Btw, exactly. Occam's razor http://math.ucr.edu/home/baez/... cuts out any such superfluous bs from science. We have a solar neutrino problem, http://en.wikipedia.org/wiki/S... , we cannot detect all the neutrinos that are supposed to be flooding us from the Sun, so we suppose that they have a very weak interaction coefficient, but to really fit the graph, we need one more object concocted, a neutrino mass. My college professor said give me 19 independent variables, and I can fit an elephant with a graph. Give me 20, and I can accurately fit the tail too. Occam's razor is against such things. Observational evidence showing neutrinos propagating faster than light is exciting, not disheartening!

The real answer to the solar neutrino problem is that there is no fusion going on inside the Sun. Yeah, you heard that right, time to revise all science textbooks. Or how else do you explain that a tiny little object in the night sky sets off not one, but three neutrino detectors worldwide, but we keep listening to the neutrinos from the Sun and they ain't coming, when in fact the detectors should be flooded and drowned in solar neutrino signals, and ignore distant galaxy events. Fact is there is no fusion going on inside the Sun, the Sun is only hot for the same reason the inside of the Earth is hot: Thorium, Uranium 238 and 235, and Potassium-40. In fact that is why an asteroid is cold, the Moon has no molten lava, because it's too small, nor does Mars, or Mercury, but Venus is sufficiently large to possess one, Earth is larger, and Jupiter, underneath all that hydrogen, is probably even hotter than Earth, and so are probably Saturn, Uranus, and Neptune, depending on the size of their silicate-cores. If you dumped a bunch of silicate asteroids with terrestrial abundance of thorium, uranium and potassium-40, together, into an Earth-sized mass, you'd get a planet with a molten inside, and a certain degree of surface temperature just from that, and total heat emissions. If you gathered enough similar asteroids and planets in extra-solar-system space, and dumped it all together to form an object the mass of the Sun, you'd pretty much get a Sun, with 5778 K surface temperature, not just molten volcano lava underneath a cold crust, but the whole surface would be volcano lava. Under such mass the gravity would be big enough to hold back even hydrogen, even at that 5800 K temperature, but as holding more and more back increases size, it increases gravity and increases compression and accelerates the nuclear reactor, i.e., the temperature goes up, and hydrogen gets boiled off and shot off as solar wind, and the Sun has a somewhat steady size, instead of an ever-growing one. Such compression/temperature rise cycles, blowing off hydrogen into outer space, it cooling by thermal radiation, falling back onto the Sun, with very long characteristic times, could explain ice-ages and global warming ages, as hydrogen can take a long trip all the way past Pluto, then stop, then get slowly accelerated back and fall back unto the Sun, and this whole thing could be steady state, but once in a while you have a massive comet or what not bring new fuel, or create a cold spot, or what not, and create minute fluctuations that could self amplify into full scale ice ages. But helium, being 4 times heavier than hydrogen, stays down, so the reason for the 75% hydrogen and 25% He in the Sun is a simple distillation process by molten lava down below, not a fusion conversion of hydrogen to helium, else our neutrino detectors would be screaming and not even noticing a distant SN1987A under the heavy noise. In fact when you look up in the sky and you see all the stars, that's pretty much all the matter there is in the Universe, so to speak, because if it gets massive, it gets hot by the natural abundance of nuclear isotopes, everything massive enough is a natural nuclear reactor fueled by the diffuse, trace, nuclear isotop

Re:Which means

[Anonymous Coward]

Wonderful, you found an alternate explanation for why 2/3 of the expected neutrinos from the sun were missing. Unfortunately that is about 15 years out of date now, since more modern detectors that can detect all three flavors of neutrinos show three times as many neutrinos from the sun as the older ones only sensitive to electron neutrinos, matching the total prediction from fusion quite well. You would still have to address observations of neutrino oscillations from non-solar neutrinos, including atmospheric ones and ones from nuclear reactors and accelerator facilities. Those last cases especially have a well known production rate that allows for accurate confirmation of the interaction strength and detector sensitivity.

Re:Which means

[sillybilly]

I beg to differ.

Where are these new detectors, and how do they detect different flavors of neutrinos? Neutrino detectors are humongous contraptions deep underground, most catching scintillations. There isn't much to "tune" to catch, and the 1987 event catching two different types of neutrinos from a single event (unless you have a theory of stage-wise double step collapse, the first one giving electron neutrinos, the second muon neutrinos, or even if same kind, but different kabooms) shows that old school detectors have no problem picking up small amounts of neutrinos from a tiny portion of the sky, and they interact just fine, and the stuff we measure as solar neutrinos is probably coming from actual neutrino producing things, but not our Sun.

Re:Which means

[Anonymous Coward]

Where are these new detectors, and how do they detect different flavors of neutrinos? Neutrino detectors are humongous contraptions deep underground, most catching scintillations

The original Homestake experiment used nuclear reactions that only worked with electron neutrinos, and early Cerenkov experiments used only electron elastic collisions which is by far mostly involves electron neutrinos. SNO which first operated in 1999 uses heavy water on the other hand, which allows for an interaction where the neutrino splits the deuterons in half, which doesn't care which flavor of neutrino is involved. They also can observe the old electron elastic scattering that previous experiments see, and had a measure of which direction the neutrinos came from. They got exactly what was expected: three times the signal for the generic process from the Sun versus the same one third of what was expected from the method in common with older experiments. They also could see that neutrino oscillations occurred in atmospheric neutrinos: atmospheric neutrinos from above were all electron neutrions, whereas ones from the atmosphere on the other side of the Earth had partially turned into muon neutrinos. Like other experiments, they can observe neutrinos from particle accelerators, which is used to double check the calibration and background of such experiments, in addition to doing careful checks for oscillations again, with yet another source.

There isn't much to "tune" to catch, and the 1987 event catching two different types of neutrinos from a single event (unless you have a theory of stage-wise double step collapse, the first one giving electron neutrinos, the second muon neutrinos, or even if same kind, but different kabooms)

Doesn't matter what they were, at that distance they would have oscillated enough to be a mix of all three flavors by the time they got to Earth. Kamiokande-II, IMB, and BNO at the time could only detect electron neutrinos and together all three saw a total of 24 neutrinos. Since the neutrions from the supernova should have been a mix, it didn't matter that they could only see three. And while the supernova was about 10 billion times further away than the sun, a supernova is estimated to produce 10^58 neutrinos while the Sun is estimated to produce about 10^28 per second... so despite the distance it would have billion times higher flux within the 10 seconds they were detected over. These days, projects like SNO detect 3000 solar neutrinos a year, as they've improved sensitivity by a lot.

As far as tuning, every particle detector of any kind has a limited energy range over which it works, and understanding that is important to knowing what sources you're sensitive to and how sensitive. This is where calibration from things like nuclear reactors and particle accelerators can be useful for, to confirm it is detecting what they think it is. The IceCube neutrino telescope for instance has a low energy limit of about 100 GeV, so it does not see solar neutrinos at all. Today there are nearly a dozen different detectors, using many different techniques, and all of the ones that are sensitive to solar neutrinos get results in agreement with fusion predictions. Not only just in terms of total number seen, but also the energy spectrum, and can see neutrinos from different nuclear reactions within the sun in proportions in agreement with the standard solar model. And if you think something else is producing them, you would have to explain why it follows the sun since these detectors can determine directions of incoming neutrinos.

Re:Which means

[sillybilly]

OK, let's assume the Sun has no hydrogen at all, and all its mass is made of the same material as Earth.
According to http://nssdc.gsfc.nasa.gov/pla... the Sun is about 2e30 (i.e. 2x10^30) kg.
According to ditto, luminosity is 3.85E26 J/s, or W. According to http://en.wikipedia.org/wiki/G... the Earth's inner lava heat comes from
232 Th at 3.27E-12 W/kg mantle
238 U at 2.91E-12
40 K at 1.08E-12
235 U at 0.125E-12
Adding these up you get 7.39E-12 W/kg mantle. Multiplying by the solar mass you get 1.47E19 W, which is much less than the luminosity, by about 26E6 times.

Btw, at 3000 solar neutrinos a year, that's one every 2.92 hrs, out of the 10^28/s*3600*2.92=1.05E32 neutrinos per year (granted most of them fly off to somewhere else, the solid angle of Earth from the Sun is small.) With Avogadro number at 6.023E23, 1E28/s is 16603 moles of neutrino/s, or, on the ballpark of 1 hydrogen atom per neutrino at 16.6 kg/s converted, while the http://en.wikipedia.org/wiki/N... page has a picture saying the Sun fuses 620 million metric tons of hydrogen per second. So the fraction of hydrogen atoms fusing that produce a neutrino is that small? 620E9 kg/s vs. 16.6 kg/s?

I'm sleepy now, and I haven't even read the wikipedia page on neutrino detectors yet. But it's the weekend, I'll read up on it, and maybe post more later.

I've had thoughts about how we assume that extragalactic space is pure vacuum, when it might actually be pretty dense gas compared to what we think it is, and that could explain why so many galaxies are spiral (spiral galaxies are like fish-swirls on the surface of a pond, when there was no rotation to begin with, just a downward sinking motion, rotation, angular momentum, and swirls generated by the sinking from slight instabilities) and vacuum happens only where the extragalactic smooth uniform gas-soup collapses gravitationally, kind of like throwing a magnet on an iron dust filled paper, it's vacuum near the magnet, and there might be a minimum vacuum point in the solar system), why they lost track of the Voyager probes (true the antenna distance was huge, but it might have been an aerodynamic drag by the weak vacuum,) why extra solar system spaceships then need to be aerodynamic with shuttle like reentry heat shields, and then how other fast flying objects out there impacting this ever permeating "dark energy" hydrogen soup would glow from shuttle like reentry heat shield effects, or shooting star meteorite heating effects, stuff you see on a lot of astronomical pictures (the heat in the rings might be partly exploding material, but what if it wasn't originally glowing when it was propelled to high speed - I don't know, can such a thing be out there? Like what's the temperature of a black hole, can it be cold and can that explode? So anyway, if there is aerodynamic drag past Pluto, then the Voyager probes have a finite distance from us where they will stop due to that drag, and interstellar travel then requires continuous propulsion and very low speeds, but possibly abundant fuel everywhere.

What are the proofs that extragalactic space is full vacuum? Even if all matter has coalesced into mostly galaxies, quite a bit may still be out there, and the vacuum inside galaxies might be stronger than outside them. us Still, what kind of rate of neutrinos does a calibration device generate, and do you have to wait like a whole year before you pick up a signal?

Re:Which means

[sillybilly]

Like Saturn's rings haven't collapsed gravitationally, what's keeping that strange thing stable? Any good math? Yeah, from google I see Maxwell went at it, that's another yummi thing to read up on this weekend.

Re:Which means

[Anonymous Coward]

Btw, at 3000 solar neutrinos a year, that's one every 2.92 hrs, out of the 10^28/s*3600*2.92=1.05E32 neutrinos per year (granted most of them fly off to somewhere else, the solid angle of Earth from the Sun is small.) With Avogadro number at 6.023E23, 1E28/s is 16603 moles of neutrino/s, or, on the ballpark of 1 hydrogen atom per neutrino at 16.6 kg/s converted, while the http://en.wikipedia.org/wiki/N... [wikipedia.org] page has a picture saying the Sun fuses 620 million metric tons of hydrogen per second. So the fraction of hydrogen atoms fusing that produce a neutrino is that small? 620E9 kg/s vs. 16.6 kg/s?

I made a typo, the number of neutrinos from the Sun should have been more on the order of 10^38, not 10^28. That does mean that the flux of solar neutrinos is on the same order as the flux from SN1987a, but that comparison doesn't matter too much as detectors, especially earlier are much more sensitive to higher energy neutrinos. And not every reaction with a proton produces a neutrino, as p+p does, but p+D does not, etc.

SNO for example, is not sensitive to lower energy neutrinos, especially the most common solar one that comes from the p+p->D+v_e+e+ reaction. The most energetic neutrino in large numbers from the Sun is from the decay of boron-8, which comes up from one of the side chains of the p+p fusion chain reaction, but that particular reaction only produces about 0.02% of the neutrinos from the Sun. Considering SNO has a 6 m radius, about 4*10^20 solar neutrinos would pass through it in 3 hours. But the vast majority of neutrinos go through the detector, and even the whole Earth without hitting anything.

A neutrino going through the Earth goes through about 10 million times as much stuff as just going through the SNO detector. Suppose only 1% would be blocked by the Earth, that would mean only one in a billion would hit the SNO detector. The actual attenuation by the Earth in the energy range of solar neutrinos is more on the order of ten parts per billion. So considering SNO was only on about half the year, could only detect 0.02% of neutrinos from the Sun with enough energy, and was has a ten millionth as much stuff as the Earth to pass through which only stops ~10 out of a billion, that there gives a signal attenuation of about 10^-4*10^-8*10^-7=10^-19. And this is over simplifying the chances of getting the right type of reaction it can see, as each of the three interactions mentioned above have different chances of happening which is different from when the neutrino is going through the Earth, so it is not as simple as estimating how much "stuff" it has to go through by mass, which is where the last factor of 10 comes from.

Other experiments were sensitive to different energies and get the other reactions within the Sun. The original Homestake was sensitive to a neutrino from beryllium-7 reaction that produces about a seventh of the solar neutrinos. GALLEX using gallium could measure neutrinos from the p+p reaction (although gallium is more expensive than water, so it had a much smaller size than something like SNO). More recent Borexino can detect the neutrinos from a all of those reactions plus some really rare ones to build up a broad energy spectrum of the neutrinos from the Sun.

As far as the space between stars, we have observational data there. Cold gases between us and near by stars show up as absorption lines in spectra of near by objects, and include lines that wouldn't otherwise be seen in a hot object, and allow you to estimate how much hydrogen or other gases that light went through to get here. Hotter gases have emission lines that can be mapped out directly, and also some interesting techniques like seeing reflections from things like pulsars and supernova. Really hot gases can be mapped out from x-rays (including some intergalactic medium too, which isn't completely empty, but seen to have densities on the order of 10-1000 atoms per cubic meter). A lot of

Re:Which means

[sillybilly]

10 to 1000 atoms per cubic meter is really deep vacuum and it means we could get interstellar travel by going really fast, continuously accelerating with a cyclotron drive to close to speed of light, say 80%, then turn to decelerating halfway there.

Your arguments are sound. A lot of stuff out there would mean a blue sky everywhere, as gases do Rayleigh scattering of light. And once you go past our atmosphere, the rest of the Universe is black, not blue, the blue sky disappears, therefore there is deep vacuum everywhere, or at least small particle free space, and then you have to invent something else that is particle free but present in vacuum and retards photons compared to neutrinos, such as gravity, or dark energy, or whatnot.

Photons interact a lot with "subspace" vacuum and get delayed, but neutrinos do not, or not to the same extent. If you're absolutely certain that neutrinos can oscillate, and there are different kinds that can turn into each other, then having two pulses does not make sense if they were both from the same event, as any different neutrinos should have oscillated into each other and be indistinguishable. One question, when we talk of photons, it's hard to talk about polarization, but we know light is a transverse wave and polarized. Obviously neutrinos have an associated wave-particle duality to them, just like everything else, and do we know what kind of waves they are? Longitudinal, or transverse? If they are transverse waves, then there could be neutrino polarization, and just like with light birefringence in a calcite crystal, where an incoming uniformly random polarized wave splits into a fast and a slow beam, based on polarization, so if the space between us and the supernova is anisotropic in any sense, such as gravity pointing in certain direction throughout, and neutrinos be polarized transverse waves, then there could be a fast and a slow wave with them, but not so with the light wave, unless they had polarized light receptors and have info on the polarization makeup of the light received vs. time (and this would be low intensity for a while, then intensity doubling when the slow beam arrives too and adds to the fast one, as light emission was continuous with a slow decay, but the neutrino came in pulses.) So if gravity affects the speed of light, and affects it in a birefringent way, it may also affect the speed of neutrinos, if they are transverse polarized, in a birefringent way too, and then none of the signals really arrived at the speed of light, but slower, as in a calcite crystal even the fast wave still has a reduced speed from true speed of light.

By the way I still don't comprehend the concept of how a uniformly polarized beam decides to split into two in a calcite crystal, instead of a spread spectrum, like how does a wave just below 44.9 degrees decide to go with one beam, then one at 45.1 degrees with the other beam, or is that the cutoff point, the math must be really complicated, but a lot of XIX century mathematicians well versed in such things would probably have no problem explaining why.

Also, looking at the double slit experiments, an electron is a wave that passes through both holes, then it decides to collapse at some point on the screen, how does a wave decide to become a particle, or even if not a particle, an interaction, in effect we have no particles, just waves, and they interact at given points, sometimes within very strict limits on location, such as a particle trace in a cloud chamber, sometimes in very random locations, such as where an electron collapses on a screen after having passed through a double slit. Many double slits in series of course would confine the electron to a linear path too, just like a cloud chamber cloud does, if the electron found a way to not interact with the walls in series, a sort of filtering effect. One that interacts with the wall off angle through diffraction then changes its mind and returns to being an electron on the original straight path, would be like the particle going through the

Re:Which means

[sillybilly]

Now I woke up, if I don't think hard I'm not that sleepy - so apropo blue sky, I had this thought right before falling asleep that don't we have evidence that the farther a star or galaxy is, the more red shifted they are? As in the more Rayleigh scattering the farther away they are, and we may not really see the blue sky as blue, but we can tell from a red shifted star that it lost a lot of blue ? But I know redshift is due to Doppler effect, and all the known spectral lines move, in unison, according to the Doppler formula, as opposed to just simply being selectively filtered out in a wavelength dependent way due to Rayleigh scattering, according to the Rayleigh formula, so no, the redshift is not due to extra stuff, but speed.

Re:Which means

[sillybilly]

By the way, if light, as it travels, creates these Heisenberg uncertainty fluctuation particle/antiparticle pairs, why don't these particle/antiparticle pairs Rayleigh self-scatter light, as in one photon goes through this slowdown, and scatters the 2nd photon (or more exactly wave packet, wave quantum) coming right behind it? That could be part of the explanation of redshift of distant galaxies, as opposed to them running faster the farther away they are, creating this Big Bang picture, they might be sitting still and light simply traveling long long long distances self-scatters in a Rayleigh way and somehow coming out of the scattering it actually shifts the atomic emission band frequency down as opposed to just filter it? Can you pull off or eke out such an explanation? I really don't like the theory where very distant galaxies are running away faster than the speed of light from us, in our reference frame, and it's OK as long as our 3D Universe is a volume on a 4D sphere, stretching very fast, and locally, everywhere you still have limited speed of light.

And how do you describe particle antiparticle pairs as wave-antiwave packets? There may really not be such a thing as a particle, and everything is just a certain vibration of "ether", with specific rules of what kinds of vibrations are allowed, and how the vibrations suddenly collapse, and there is no such thing as a "transformation" of a photon into a million kind of particle/antiparticle pairs, but more like a vibration encountering an already present fluctuation, and interacting with it. Vacuum might have a structure that allows certain types of wave packets with definite rules and axioms that interact through collapses of the wave that spread over an entire galaxy, at a single nanosized point on a screen, and string theory might be beating around the bush, but it requires 26 or so dimensions rolled up, and Occam's razor is very eager to cut crap with 26 dimensions. Btw we can thank a lot of Occam's razor http://math.ucr.edu/home/baez/.... Through it we killed phlogiston, caloric, vis viva and ether as useless concepts. Phlogiston got killed by Lavoisier, Mr. Oxygen and his wife in 1778 (Jean Michel Jarre has an album titled Oxygen), "vis viva" got killed by Wohler in 1828 by making "organic" urea out of "inorganic" ammonium cyanate, organic materials previously thought to have require life-force, or vis viva to be created. Caloric (which, btw, was introduced by Lavoisier himself, such is science, you win some, you lose some, oh well) was killed by Joule in 1843, showing that heat is not a conserved fluid, but can be generated. And Einstein and his wife killed the concept of "ether" in 1905 based on the Michelson-Morley experiment trying to measure the speed of Earth through ether with unprecedented accuracy with a superb interferometer suspended on a pool of mercury in 1879 at Western Reserve University. When you had man/woman duos doing the work, as in Einstein or Lavoisier, it's probably impossible to separate the individual contributions of the two, and assign credit as credit is due, 35% going to one person, 65% to the other. By the way Lavoisier's head rolled during the French Revolution, because he made a living through the tax office, concocting even better ways to extort even more money out of the people. And during the guillotine sessions, when a whole lot of nobility family trees were instantly trimmed, before chopped some heads were told to keep blinking as long as possible after they are chopped, and they could do it for about 35 seconds before giving out. So even getting your head chopped is not instant death, and hanging is probably not so either, there is mental awareness, anguish and agony for at least 35 seconds. Lethal injection, preparing the inmate, tying him down, that creates a lot of stress right there, and probably the most humane way of execution is not telling a death row inmate when he's gonna go, gassing him in his cell/chamber with anesthetics, then wi

Re:Which means

[sillybilly]

I pass way to many typos these days. Like piece/peace. Sometimes it feels like as I type below, somebody keeps changing the stuff I typed above. You can not trust these newer browsers with xmlhttprequest and html 4 dom not changing stuff on the fly for you, without a page reload, as you type.

Re:Which means

[Anonymous Coward]

why don't these particle/antiparticle pairs Rayleigh self-scatter light

Photon-photon scattering, only relevant at very high energy levels or field strengths, otherwise chances of it happening are essentially zero.

And how do you describe particle antiparticle pairs as wave-antiwave packets?

Diract equation and Quantum field theory, the latter is usually a required intro course in grad school and will breeze through the former in the first month or less. There are a large number of books on the subject of varying level.

Re:Which means

[sillybilly]

By the way the Inca's are the most fervent Catholics in the whole world these days. During Easter they reenact the crucifixion of Christ, by some people actually getting nailed to a cross and bleeding, and they get carried around like that on a procession. That bloody gore fits in line well with their ancient traditions of human sacrifices. Both the Inca's and Aztecs practiced human sacrifices up to the time of the arrival of conquistadors, and while the Aztecs as an empire disappeared from an economic collapse from overgrowing past their resource limits (just like Angkor Wat collapsed near VietNam), the people remained, scattered about in the jungle, living subsistence lives, without much complex science and technology or art or religion. The Inca's on the other hand were just done conquering the neighborhood, they were at the apex of their powers when they had the bad luck of the conquistadors arriving, bringing the "brotherly love" of Jesus on the cross to them, in the form of a sword. That's what you call hypocrisy, btw.

Re:Which means

[sillybilly]

The real issue with Rayleigh self scattering of light is that it does not explain red shift. The energy has to go somewhere, something has to take it, unless a photon turns into a particle/antiparticle, it Rayleigh-scatters the photon coming behind it to a red-shifted frequency (scattering is a filtering, not a frequency-shifting like Doppler) then the particle/antiparticle emit in a laser-way another photon, then go back to their original state of a photon. In this way red shift would mean increasing the intensity of light while decreasing the frequency, instead of 2 photons that are, say, blue, you'd end up with 3 photons that are red, all with very close frequencies. I don't think the math could do that. By the way I never really got why in laser, a light of the same frequency triggers the spontaneous emission of inverted populations, in a pulse. Why? Why can't it be a light of higher or lower frequency that triggers the collapse? And if it's a triggered collapse, then how do continuous lasers, like the laser pointer on my keychain, work? Many triggered pulses in sequence? Or the semiconductor is just efficient in putting a lot of electrons into the high state? Why is one LED just an LED, of a definite nm wavelength light, another one a laser LED, with a similar nm wavelength, what makes one a laser but not the other? See, there is lots of stuff I don't know.

As far as the Dirac equation and the like goes, I know it modified the Schroedinger equation with special relativity, and because of the squared term, you had two solutions, plus and minus, and that's how the positron was discovered, and matter/antimatter in general. But still, it does not have any more info on wavefunction particle-like behavior, called collapse, more than the Schroedinger equation does. See light used to be thought of as electromagnetic waves, until Einstein explained the photoelectric effect via particles, that only particles can be counted as 1, 2, 3. I feel the particle description lacks richness, compared to a wave description, that spreads over the entire galaxy then collapses at a single point of interaction. It's like describing something as both scalar and vector, and the vector description is the "correct" one, because it has more features, and scalars are just a particular sub-case of vectors. When we model the world around us, we can come up with better and better models, but even as Einstein said it, some new theory may come and replace the existing ones, only relegating them to relevance through correspondence principle ways, such as Newtonian mechanincs, at low speed, corresponds to special relativity at low speed, and special relativity is just an extension of the rules for those special cases. All Plack derived is that energy is emitted and arrives in packets, not whether it's particles or waves, and as far as we know it, wave-packet is what he got. A wave packet can have a polarization attribute, just like a photon-wave-packet, but how do you assign polarization to the other de-Broglie wave things? De Broglie does not specify whether the waves are transverse or longitudinal, and for photons we know they are transverse, but what about the rest? The clearest evidence of waves being better descriptors with richer sets of features, better models, is the electron diffraction double slit experiment. The single electron whose wave function collapses at a single point on the screen, went through both holes, it knows about both holes on an individual basis, it self diffracts. You cannot explain such behavior with any kind of limited to a point in space particle feature, but a spread out all over the friggin universe wave that goes through both holes at the same time, then collapses the whole wave from the whole universe at a single point, seems like a fitting an suitable description. They shouldn't talk about particle science and particle physics, all you got it wavelet, wave-chunk, wave-quanta physics. It explains the photoelectric effect, polarization behavior of photons, it explains lots of things. Ultimately no model is per

So, what's the correction?

[TWX]

Since they've established the difference between the theoretically-idealized neutrino and the observed photon, do they correct the idealized, or do they correct the observed?

Re:So, what's the correction?

[ShanghaiBill]

do they correct the idealized, or do they correct the observed?

Neither. You cannot correct the speed of light, because it isn't measured, it is DEFINED as EXACTLY 299,792,458 meters per second. So it is not the speed of light that needs to be updated, but the length of the meter.

Re:So, what's the correction?

[jae471]

Neither. Because neither is wrong. And the article is trying to sensationalize a claim the scientists didn't make.

It is the average speed of the light over very large distances that needs a correction, to account for the portions of travel where the light, well, is not light. The photons still move at 2.99x10^8m/s. It's the electrons and positrons that move slower.

Re:So, what's the correction?

[Anonymous Coward]

Every time I fuck my wife, she says I'm "correcting the speed of light".

Re:So, what's the correction?

[Anonymous Coward]

You have this the wrong way around. The speed of light is not defined, it is a universal constant. It is the length of the meter that is defined based on a combination of this constant, and the international standard of time. So you are correct that if light turned out to travel slower, the length of the meter would be slightly shorter, and the speed of light would still be exactly 299792458 meter per second. This would be according to the new length of the meter though, when expressed in the old length (which is what the poster is implicitly asking for), it would most certainly be less, and could be given as such.

Of course the truth is that the speed of light is perfectly fine as it is. It's just that light isn't always exactly 'light' when it travels through space.

Re:So, what's the correction?

[Anonymous Coward]

"c" is defined as 299,792,458 meters per second, which is the idealized speed of light. The practical speed of light can be slower, like when propagating through glass. If this new data is correct, then neutrinos move faster than photons through a gravitational potential.

Re:So, what's the correction?

[Em Adespoton]

None of this is the issue; speed of light stays constant, as does distance measurements. What changes is the understanding of the stability of a photon of light in a vacuum and the effect of this instability on travel time while passing near a gravitational well.

So while it's a photon of light, it travels light speed. When the energy converts to kinetic energy for a breather, it is affected by the gravitational pull, in a manner significantly stronger than a neutrino is affected. When it then flops back to being a photon, it is once again traveling at the speed of light.

What intrigues me about this is that this will also have implications regarding relativity, as every time the light flips state, it is essentially anchoring itself to a location in space from which the next photon flop can take its bearing. My mind can't quite grasp the further implications of this right now, but it could really mess with observation of light from a moving point (which all points are).

The recalibration is mostly on how we project distances based on light measurements; it's now become significantly trickier, as we need to account for gravity at specific moments.

Re:So, what's the correction?

[msauve]

That's my understanding, too. They're simply trying to describe the index of refraction for deep space.

Re:So, what's the correction?

[Anonymous Coward]

Depends on the base really..... In base "speed-of-light" the speed of light is actually just "1.0".
As a percentage it's 100% and most things in the universe are at less than 1%.

Hell I could even change the base notation *before* meters.... Meters are now in Hex... you have 0xFF meters.
Or since speed references time, I could argue that time itself is simply warping around an object due to it's excessive speed making it "seem" to be faster.

How do we know time isn't the variable that changes here.... the objects were *always* moving at the speed of light, but time was experienced differently because the two objects (us and the particles) were moving at drastically different speeds over enough distance that the time-difference is measurable.

I'd say this proves time warps more than any proof over changing speed of light. When time changes how do you measure speed?

Re:So, what's the correction?

[hsthompson69]

It's just that light isn't always exactly 'light' when it travels through space.

*This*.

It would've been better if they had focused on the transformation of light over time as it travels through space - that shit is interesting as all hell.

Re:So, what's the correction?

[lazy genes]

I would never trust a photon for more than 1 million light years.

Re:So, what's the correction?

[Anonymous Coward]

A more fundamental question is why is there a limit to the speed of light? Why is the maximum speed 299,792,458 m/s in vacuum? Why not 1 m/s higher? To me something is 'holding back' a photon in vacuum, even though it has no mass. It is not the Higgs since it only reacts with massive particles. Another question is why is the speed of light absolute? What's so special about photon, whose properties we know exactly, that cause it to define absoluteness in our universe? Looking at the quantum properties of photon there is nothing that tells you its speed is absolute. The maximum speed and absoluteness of photons are related, and points to a yet undiscovered most fundamental property of the universe that must be present before the big bang inflation event.

Re:So, what's the correction?

[lgw]

An easier example of this: light moves much slower than c in glass, or in water. The open question is: does light move non-trivially slower than c in the vacuum of space (which is not an idealized vacuum).

Re:So, what's the correction?

[Anonymous Coward]

The speed of light is not defined, it is a universal constant.

It is a constant that depends on units, and hence has to either be defined or derived from other definitions and constants. If you switch between two different units, like m/s vs. miles per second, you get two different numbers. Changes in the number alone are indistinguishable from changes in units. Unitless constants on the other hand are the ones that can't be defined to be a specific number and instead a universal value. When one talks of changes in the speed of light, they mean relative to something else, which means somewhere a unitless value has changed, otherwise you've just defined a new unit. This is part of how theorist just can set a number of constants equal to one to make equations easier to write (e.g. setting c and G to 1).

Re:So, what's the correction?

[Anonymous Coward]

I wonder if it has the potential to change any dates regarding the age of the universe.

Re:So, what's the correction?

[Anonymous Coward]

Maybe the light couldn't make the run in under 12 parsecs

Re:So, what's the correction?

[SQLGuru]

The way I read it, the speed of light (in a vacuum) isn't changed by this article.....just the expected speed of photons through a gravitational field of large enough mass and enough distance.

Re:So, what's the correction?

[Anonymous Coward]

There is exactly one problem with this claim that should be immediately measurable.

Heavier photons (read: shorter wavelengths) require less energy gain to convert to electron-positron pairs and so each pair can exist for longer without violating the constraint in the uncertainty principle and so be slowed down more.

Re:So, what's the correction?

[Anonymous Coward]

This effect is predicted to be independent of wavelength as calculated, as the effects of different photon energies cancel out when discussing virtual pair production, as opposed to real pair production the depends heavily on energy.

Re:So, what's the correction?

[Anonymous Coward]

Depends upon your definition of non-trivial.

It loses 4 hour over a ~160,000 light year distance. Thats .000000285 % difference

Re:So, what's the correction?

[Anonymous Coward]

The problem here is that we can only measure the end results and don't "see" what happens in between. I've read a paper that stated that light as an uninterrupted wave/photon always propagates at "c". The slower "practical speed of light" through a medium are due to interactions with matter. When light travels through a medium containing matter it will be absorbed and "stored", for some time, in the exited states of the atoms before it is emitted again. This can account for the "slowing" down effect, which again means that the photon you measure with your photon detector wasn't actually slowed down, it simply not the same photon that was emitted from your photon source.
Sounds like splitting hairs? In the context with the phenomena of vacuum polarization it's not surprising for me that similar delay effects can be observed here.

Re:So, what's the correction?

[Bryan Ischo]

In my conception (which may be flawed; I came to this conclusion after university physics classes that I didn't always understand as well as I should have, and these were 20+ years ago), the speed of light is governed by "the rate at which things can happen".

Electromagnetic waves propogate because a changing electric field produces a changing magnetic field which produces a changing electric field, etc. For reasons that I can't remember these changing fields occur in a slightly offset position each time, so that the fields move through space as they create each other.

If causes and effects could occur at an infinite rate, the waves would move infinitely fast; but since there always has to be a time gap between a cause and an effect, there is a fixed upper bounds for the rate at which these fields can produce each other.

There is also a fixed lower bounds on the minimum offset that can occur between the electric and magnetic fields.

So what you have is essentially effects occurring as quickly as possible over distances as small as possible. The ratio of the smallest possible time between a cause and an effect, and the smallest possible distance between an electric field and the magnetic field it produces and vice versa is ... the speed of light.

So why can't light go faster than c? Two reasons really: a) things "can't happen" faster than the cause-effect relationship of a magnetic field producing an electric field, and vice-versa; and b) distances between an electric field and the magnetic field it produces, and vice-versa, can't be smaller.

I vaguely remember that this is related to one of the cool aspects of Calculus - the ability to take the ratio of an infinitesimally small number to another infinitesimally small number, each expressed as a limit approaching zero, and get a calculatable, real number result.

In this case, if you take the limit as distance approaches zero, divided by time as it approaches zero, you get the speed of light - the ratio of two infinitesimally small numbers (the smallest unit of distance over the smallest unit of time).

Anyway that's how I explain it to myself.

Re:So, what's the correction?

[Anonymous Coward]

I like it. If something moves at the speed of light in a vacuum, then it does not experience the passing of time. As things approach light speed, the time they experience slows and is stopped at light speed. Things don't seem to accelerate to light speed, they just are if they're gonna be.

Then the emitted photon leaves one atom and absorbs into another without knowing it has moved. Now if a photon switches into a slower form for the tiniest moment then it gets to feel time and change a bit. I wondered if the light leaving the supernova is instantly touching us and everything else from it's perspective. Kind of feels like we are connected to everything emitting light. The Earth is not touching Jupiter or the Sun. Instantly passing a light photon doesn't seem to be happening.

So a photon travels and spreads (wave intensity lowers by the cube of distance) But it spreads far enough and pops into two charged particles that pull back together. It keeps the photon traveling in a straight line and not dissipating. I wonder if his idea could be measured with interferometry. The article says not. We're on spinning planet, might be a pain to get a single photon to travel a long way and do a double slit experiment to catch breaking up and slowing.

Wonder if bending light with a magnetic field is not moving the "rotating" light wave, but pulling/pushing on the double charged particles for the tiny time they exist.

Re:So, what's the correction?

[Collective 0-0009]

Well does light ALWAYS travel in this manner over long distances? If so, then we do need to adjust it. Otherwise it sounds like car manufacturers that measure MPG in perfect conditions in a wind tunnel and ignores the realities of wind resistance in the real world while the gas pump cares not what the window said when you bought it.

Re:So, what's the correction?

[CyberBill]

SN 1987A is approximately 167,885 light years away, and they are showing a change of around 4 hours.

4 hours divided by 167,885 years (4029240 hours) = ~0.00001% (I hope I did that math correctly).

So like.. if the age of the Universe is 13.7 billion years, we would incorrectly believe it was 13.7000137 billion years old.

Re:So, what's the correction?

[dcollins117]

None of your questions can be answered by science. Science is a great tool, but can't answer "why" things are the way they are. Just be grateful it is not different, otherwise we wouldn't even be here to ask the questions.

Similarly, asking what happened before the big bang is meaningless. Stephen Hawking puts it beautifully:

Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang. Events before the Big Bang, are simply not defined, because there's no way one could measure what happened at them.

This doesn't mean you can't enjoy pondering these questions if that's what you want to do, but do so with full realization you're now in the realm of philosophy, religion, and mysticism - not science.

Re:So, what's the correction?

[Anonymous Coward]

Do you have a citation for that paper? Because that sounds like a direct contradiction to stuff like observation and Maxwell's equations. The slowing down for something, especially waves much larger than the atoms in the medium, comes from inducing currents and charge movements that partially cancel out the fields of the light in such a way that the oscillating fields move slower. There is not jumps and spurts of higher velocity for such larger wavelengths where you can still clearly see slowing from media. At very short wavelengths on the order of the size of atoms or smaller, you get such effects, but as scattering that involves the light changing direction when it collides with the atoms or other particles as there is no guarantee it will come out at exactly the same energy and direction. Even then, you can have index of refraction effects that change the propagation speed even of things like x-rays, although very subtle, that don't involve getting absorbed (which would ionize atoms, etc, depending on energies and materials involved).

Re:So, what's the correction?

[Anonymous Coward]

Wonder if bending light with a magnetic field is not moving the "rotating" light wave, but pulling/pushing on the double charged particles for the tiny time they exist.

There is an effect for bending light due to it splitting up into virtual pairs and interacting with a magnetic (or electric) field, but it only works on very extreme fields (near a nucleus, or near a pulsar) and the wavelength dependence is so strong you will only see it acting on high energy gamma rays. Still doesn't allow bending of light in vacuum with any more mundane magnetic or electric field (including ones many orders of magnitude higher than the strongest ever made human magnet), and it is not even bending but a scattering process. Otherwise, except for when passing through certain media, light is not bent by magnetic fields.

Re:So, what's the correction?

[Anonymous Coward]

If causes and effects could occur at an infinite rate, the waves would move infinitely fast; but since there always has to be a time gap between a cause and an effect, there is a fixed upper bounds for the rate at which these fields can produce each other.

In a vacuum this is due to the impedance of free space, in the same way the impedance of a cable can determine propagation speed down the cable due to how long it takes for swings between magnetic and electric field, etc. But that doesn't answer a "why c" so much as just replace it with "Why epsilon_0 and mu_0, where c=1/sqrt(epislon_0 * mu_0)"

Re:So, what's the correction?

[Bryan Ischo]

Agreed. But that's kind of my point. It's easy to wonder why light has to be bounded by a maximum speed because we can easily ask "why not faster"? For me it makes it clearer that there are fundamental aspects of physics/reality at work here to keep in mind that it's really the ratio of the smallest distance to the shortest time.

Yes, you do then have to ask "why is there a smallest distance" and "why is there a shortest time", but at least for these questions, I have an answer I can live with: because there has to be a separation between cause and effect, so there has to be a shortest time in between which two things can happen. If the time that it takes for an electric field to propogate a magnetic field and vice versa, which has no time component as far as I remember in the equations governing how this happens, has nothing limiting it to happening with a shorter time duration between the cause and the effect (which I believe is true, at least according to electromegnetic theory), then this is the shortest time.

A similar argument can be applied to explaining why there is a shortest distance.

So basically, for me, it is more directly meaningful to think of there being a smallest possible time increment (because there *must be*, otherwise zeno's paradox and all that), and a shortest possible distance (once again because there *must be*, for the same reason), than to think of there being a limit to the speed of light, which otherwise logically I can't understand, except in the terms that I described in this and in my prior post.

Re:So, what's the correction?

[Anonymous Coward]

but at least for these questions, I have an answer I can live with: because there has to be a separation between cause and effect, so there has to be a shortest time in between which two things can happen.

But according to relativity, the separation can be made arbitrarily small. For any cause-effect events you can pin down, you can find a frame in which an observer would see an arbitrarily small difference in time between them (i.e. for any "smallest time separation" you can find a potential observer that would have seen a smaller time separation). That can be extrapolated to say that light doesn't see any separation in time between events, although that can end up in a quagmire of philosophical discussion that doesn't have any physically observable effect.

Re:So, what's the correction?

[Anonymous Coward]

I think you're conflating wave and particle mechanics here. I was mostly talking about the quantum mechanics of "photons", perhaps I shouldn't have mentioned "waves". Both the wave and particle perspective seem to be correct, it's simply a different way of looking at the same phenomenon, which makes it sometimes easier to describe light as wave and other times easier to describe it as a photon.
Unfortunately I don't even remember who wrote that paper because stupid me didn't care much back then. It was a question one of the students asked our professor during the physics lectures, something like "When the speed of light is a universal constant, how can it be influenced by medium like glass?". In the next lecture he showed up with a paper that was published on that topic and showed us some of the math behind it. Back then it was way over my head and didn't seem to be relevant, so I only remembered the out-lines.
But there is other research into that direction. Other than that googling the term "speed of light constant slowing down absorption" should bring up some results.

Re:So, what's the correction?

[Bryan Ischo]

Are you sure that the cause-effect relationship between an electric field propogating a magnetic field, and vice-versa, is included in this theory? Because there is no time component in the equations and therefore there is no unit of time to be made shorter.

There actually isn't any time between the change in the magnetic field and the change in the electric field; and there isn't any distance, either. But the ratio of these two values does produce a finite number, just like how calculus can calculate the ratio between the limits of two formula converging on zero at infinity.

Re:So, what's the correction?

[7-Vodka]

Actually, the length of a meter is based on the distance between the pole and the equator of the earth. It has nothing to do with the speed of light.

Re:So, what's the correction?

[Anonymous Coward]

Quantum mechanics reproduces classical electromagnetism, so the concepts seen in classical waves still apply. Additionally, wave functions describing photons and other particles will act similarly, and can have their speed change based on traveling through different potentials, but not involve any absorption. This becomes even more important when trying to preserve states for quantum mechanics experiments where a single photon being absorbed by the air or optics it is passing through would mess things up.

But there is other research into that direction [harvard.edu].

The propagation of light through various condensed matter states is no different in the sense that it can be described by reactionary fields combining with the original fields to produce a slower propagation. The storage of stopped light pulses is exactly that, where the induced effects in the medium are frozen, and then can be used to recreate the original light. A lot of those experiments are special cases where the light is close to an actual transition energy in the atoms being used (whereas other light at energies not capable of exciting an atom in a medium still experiences slower propagation), and without any external inputs a single photon of such light wouldn't just be slowed, but would randomly scattered upon being absorbed. It only continues in the same direction in storage experiments either because there are many other photons going in the same directing via stimulated emission, or through other similar effects. But under normal optics situations, most single photons at energies not matching any transitions in a medium propagate straight through with the exact same delay.

Re:So, what's the correction?

[Anonymous Coward]

You're over a hundred years out of date on the definition, as in the later 1800s it was defined based on a prototype rod, then redefined in 1960 using the wavelength of an atomic transition in krypton, then defined in terms of the speed of light in 1983.

Re:So, what's the correction?

[Anonymous Coward]

ACTUALLY the length of a meter has been defined as the distance light travels in a vacuum in 1/299,792,458 of a second. It has been since the early 1980s.

Re:So, what's the correction?

[RespekMyAthorati]

Not since 1983, when it was redefined in terms of the speed of light.

Re:So, what's the correction?

[Thanshin]

None of this is the issue; speed of light stays constant, as does distance measurements. What changes is the understanding of the stability of a photon of light in a vacuum and the effect of this instability on travel time while passing near a gravitational well.

Which is all fine and dandy except for the detail that what you're then describing as "the speed of light in vacuum" becomes different to "the speed at which light travels in vacuum", which although physically correct, would be linguistically abhorrent.

Therefore, if you want to keep the number, maybe it would be more appropriate to call that number "speed of photons" and redefine "speed of light" to the actual propagation rate of light, with vacuum polarization taken into account.

Re:So, what's the correction?

[Thanshin]

It is the average speed of the light over very large distances that needs a correction

I'll remember that next time I'm arguing a speeding fine.

"But, mr. officer, you can't fine me for breaking the speed limit. You only know the average speed I had over the distance between the two radar pulses!"

Re:So, what's the correction?

[Anonymous Coward]

I am not a professional physicist, but it has always been my understanding that there's always been a small, usually glossed-over issue as to whether the GR limiting velocity "c" and the actual speed at which light travels in a vacuum are genuinely and precisely one and the same thing (even though it's near-universal practice to refer to them as though they are). We already know that the effective speed of light certainly isn't a constant; it varies according to the medium through which the light is travelling. This result, if confirmed, would simply mean that that remains true even when the medium is "empty" space, and would provide a mechanism by which that occurs; "empty" space would have a refractive index greater than 1, and the effective speed of light in a vacuum would be a tiny (but non-zero) amount less than c.

That, of course, would leave the issue of whether the definition of the meter is based upon the speed of light or upon c - but at a time when we STILL haven't managed to stop defining our units of weight with reference to a lump of metal stuck away in a vault that gives somewhat disturbingly different results every time it's referenced, resolving that one would be trivial by comparison.

Re:So, what's the correction?

[Anonymous Coward]

It is true that it was based on the distance between the equator and the north pole but since 1983, it has been defined as "the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second. So yes if light is slower the metre gets shorter.

Re:So, what's the correction?

[Anonymous Coward]

Actually, the length of a meter is based on the distance between the pole and the equator of the earth. It has nothing to do with the speed of light.

No, that's the old definition. Since 1983 the meter has been defined as the distance travelled by light in a vacuum in 1/299,792,458 of a second.

(But, yes, the OP has it backwards - the meter is defined based on the speed of light, not the other way around.)

Re:So, what's the correction?

[ultranova]

It is the length of the meter that is defined based on a combination of this constant, and the international standard of time. So you are correct that if light turned out to travel slower, the length of the meter would be slightly shorter, and the speed of light would still be exactly 299792458 meter per second.

No, because this effect is dependent on presence of gravity, so it's our definition of "free space" that needs to be updated to specify flat spacetime.

Or we could say that meter is defined against a constant of nature - invariant speed - and photons are simply a handy way to measure it to good and possibly, at least in some circumstances, perfect precision.

Re:So, what's the correction?

[mestar]

Why is nobody mentioning the fact that the light particle does not take a single route trough space, but travels trough it in all possible ways.

Re:So, what's the correction?

[mestar]

So, when a photon travels trough a optical fiber cable, now does it know when to turn?

Total reflection you say? So, it goes near all those electrons in atoms, and then it only decides to turn once there will be no more atoms in it's current path?

Re:So, what's the correction?

[mestar]

"When light travels through a medium containing matter it will be absorbed and "stored", for some time, in the exited states of the atoms before it is emitted again."

Then the question becomes, how does the light know how to continue in the same direction it was going previously?

Re:So, what's the correction?

[gstoddart]

I have no idea what that means.

I know about the whole warticle thing, but I have no idea of what "all possible ways" is -- the event goes in all directions, but we didn't get bombarded by the particles which traveled away from us.

Other than possible effects of gravity, or passing through stuff, doesn't the like travel in mostly a straight line?

Re:So, what's the correction?

[Anonymous Coward]

The first thing you need to realize is there is no spoon.

Re:So, what's the correction?

[gstoddart]

LOL, doesn't the light travel

Need more coffee

Re:So, what's the correction?

[blueg3]

Or, more than one part in 10^6, which is larger than our measurement precision in some cases.

Re:So, what's the correction?

[Anonymous Coward]

Not quite. The "vacuum" of space was definitely less of vacuum in early stage of the universe than it is now. Hence, the speed of light was "slower" initially than it is now, as we move towards the idealized vacuum and almost reach "c". At t0, the speed of light may have been close to zero.
With that, the universe could be MUCH older than 13.7 b years. Possibly it existed for ever ?

Re:So, what's the correction?

[RivenAleem]

So you're saying that light is female, and had to stop to ask directions?

Re:So, what's the correction?

[Anonymous Coward]

The Feynman path integral used in the QFT to find how particles move from place to place is an update of the classical principal of least action, and involves essentially averaging over all possible paths to get the path it does take. This includes both paths where virtual pairs form and ones where they don't. In the end the light only takes one actual path in a sense, but it can take into account effects along the way that would have blocked or influenced other paths.

Re:So, what's the correction?

[Anonymous Coward]

Total internal reflection can be explained in terms of induced currents and polarizations in a medium canceling out the original wave at an interface (or gradient). Fermat's principle isn't the exclusive approach to such optics and is just an equivalent to other approaches such as just solving Maxwell's equations.

Re:So, what's the correction?

[Anonymous Coward]

redefine "speed of light" to the actual propagation rate of light, with vacuum polarization taken into account.

This is how the speed of light is defined now. It is not possible to measure physical properties of physical properties of particles without the effect of virtual particles, as they are always present. The values for things taking into account things like vacuum polarization is the defined, physical value. Although this assumes no interaction with outside forces and particles, which the effect discussed in the paper is an example of. So gravity could be described as changing the speed of light relative to its value in an flat vacuum.

Re:So, what's the correction?

[Toad-san]

Yep, for local use the good old accepted value of C will do very nicely. Where light is, well, light.

Re:So, what's the correction?

[Em Adespoton]

Wonder if bending light with a magnetic field is not moving the "rotating" light wave, but pulling/pushing on the double charged particles for the tiny time they exist.

There is an effect for bending light due to it splitting up into virtual pairs and interacting with a magnetic (or electric) field, but it only works on very extreme fields (near a nucleus, or near a pulsar) and the wavelength dependence is so strong you will only see it acting on high energy gamma rays. Still doesn't allow bending of light in vacuum with any more mundane magnetic or electric field (including ones many orders of magnitude higher than the strongest ever made human magnet), and it is not even bending but a scattering process. Otherwise, except for when passing through certain media, light is not bent by magnetic fields.

Hmm... but the charged particles WOULD be bent by magnetic fields. I'm not quite sure where to go with that observation though.

Re:So, what's the correction?

[Anonymous Coward]

Yeah - me too on the hurting head. So I wanna know what the implications of "This changes the energy of the virtual electron-positron pair".
Seems to me last I heard a photon was both a particle and a wave - if this "vacuum polarization" causes the photon to flip flop then what effect will the energy change affect the photon if any? I mean the energy has to have *some* effect - RTFA basically blames the slowing on this energy change due to gravity but why not accelerate?
I need beer.

Re:So, what's the correction?

[Anonymous Coward]

This is at least partially taken into account when discussing the CMB, as the whole point of why it acts like a frozen image of things that time is because the universe got cool and sparse enough for light to not be trapped, as the universe went from optically dense to optically thin.

Re:So, what's the correction?

[Anonymous Coward]

I think this comes back to the idea that the propagation of the photon is the sum over all possible paths, which includes all possible loops you can create (you integrate over all values of momentum of the particles in a loop). Effectively you will be averaging both the case where you have a electron go to the left and positron to the right with the case where the electron goes to the right and the positron goes to the left. The net effect of electric and magnetic fields will then be zero. The process still respects conservation of charge, so you end up with a total neutral charge and no net effect on that process. A scattering process is different because you have an outside particle, including the possibility of a photon from the electromagnetic field, and you have a real interaction exchanging energy and momentum (but it is scattering because you don't know which half of the loop it is going to interact with). The gravity process in the paper is also different, because both the positron and electron have the same effects from gravity, and the virtual pair is not respecting conservation of mass briefly in the same way it respected conservation of charge.

Re:So, what's the correction?

[swalve]

Maybe mathematics is what is wrong?

Re:So, what's the correction?

[david_thornley]

Yeah, but maybe spacetime is quantized on a level smaller than we can currently detect. The speed of the light might be one cube per turn, or whatever terms you want to use. We've found weirder effects in the Universe.

Re:So, what's the correction?

[david_thornley]

Then the officer either trots out a mathematical proof that says you had to be going at least as fast as the average speed at some point between the pulses, or knows enough physics to realize what the Doppler effect is, or is not educated enough to realize what the number on the radar gun means and just goes with it.

Re:So, what's the correction?

[Anonymous Coward]

Because there is no time component in the equations and therefore there is no unit of time to be made shorter.

Not sure which equations you are talking about, because Maxwell's equations explicitly contain time and the speed of light, which is where the solutions for electromagnetic waves get their speed, at least mathematically.

Re:So, what's the correction?

[uninformedLuddite]

So, when a photon travels trough a optical fiber cable, now does it know when to turn?

GPS?

Re:So, what's the correction?

[gmyuriy]

When light travels through a medium containing matter it will be absorbed and "stored", for some time, in the exited states of the atoms before it is emitted again. This can account for the "slowing" down effect, which again means that the photon you measure with your photon detector wasn't actually slowed down, it simply not the same photon that was emitted from your photon source.

THIS

This is the source of all troubles in the world - bringing in improper analogies and building "theories" upon them. Let's begin with that the photon is not a particle flying through space, it is a probability wave. Particles do not fly, the probability wave propagates. Likewise, light remains a wave in medium, and it is that wave that is slowed due to interference with the charges in atoms.

Try to explain with your little analogy the greater speed of light in some meta-materials; what, the atoms emit photon before they absorb it?

Some times it is just better to accept that your thinking platform needs a change than try to continue squeezing the world into a completely inadequate concept-box.

Re:So, what's the correction?

[gmyuriy]

None of this is the issue; speed of light stays constant, as does distance measurements. What changes is the understanding of the stability of a photon of light in a vacuum and the effect of this instability on travel time while passing near a gravitational well.

So while it's a photon of light, it travels light speed. When the energy converts to kinetic energy for a breather, it is affected by the gravitational pull, in a manner significantly stronger than a neutrino is affected. When it then flops back to being a photon, it is once again traveling at the speed of light.

What intrigues me about this is that this will also have implications regarding relativity, as every time the light flips state, it is essentially anchoring itself to a location in space from which the next photon flop can take its bearing. My mind can't quite grasp the further implications of this right now, but it could really mess with observation of light from a moving point (which all points are).

The recalibration is mostly on how we project distances based on light measurements; it's now become significantly trickier, as we need to account for gravity at specific moments.

Gravity affects energy, not mass. Regardless the photon travels as a light or as a pair of virtual electron and positron, the gravity effect is the same. Why otherwise do we have gravitational lenses. I don't really know what this article is all about; gravity and quantum theory don't quite mesh well, it is well known. This sort of result, even assuming it is conceptually and mathematically solid, which is a far stretch, is a poke in the sky.

Re:So, what's the correction?

[gmyuriy]

The light (and all other massless particles) travels at maximum speed allowed by the structure of space-time, this is what the relativity is really about. The structure of space-time is defined by SO(3,1), where "travel" actually a rotation mixing time and space coordinates. "c" is the maximum you can get. Now if you ask why should we live in SO(3,1) space-time, that's a completely different story...

Re:So, what's the correction?

[gmyuriy]

Neither. Because neither is wrong. And the article is trying to sensationalize a claim the scientists didn't make.

It is the average speed of the light over very large distances that needs a correction, to account for the portions of travel where the light, well, is not light. The photons still move at 2.99x10^8m/s. It's the electrons and positrons that move slower.

This is incorrect, virtual particles don't move slower, or move at all. They are probability waves that appear in particular space-time point and collapse at another. That's why they can annihilate again, at all; if they moved as normal particles, they should have flown at opposite directions due to conservation of momentum and never see each other again (think about that). This all happens actually at the speed of light. I feel like the paper's authors mess up with things they don't really understand.

Re:So, what's the correction?

[Anonymous Coward]

Gravity affects energy, not mass. Regardless the photon travels as a light or as a pair of virtual electron and positron, the gravity effect is the same.

The paper is making the case that in a weak field that while a photon is not deflected by EM fields since the virtual pair conserves charge, the virtual pair does not conserve energy which changes its interaction with gravity.

gravity and quantum theory don't quite mesh well, it is well known.

This just sticks a naive mass * gravitational potential into the Hamiltonian which is pretty straightforward mechanically to follow through on at least.

even assuming it is conceptually and mathematically solid

It's not. The final result depends on the value of the gravitational potential (not a difference in potentials), and even the author points out that is unphysical. The author found it interesting to get a pretty close estimate of the delay though, and the author thinks he can get a similar physical result through more careful calculations via a curved space time Dirac equation, but that is to be seen.

Re:So, what's the correction?

[Anonymous Coward]

None of this is the issue; speed of light stays constant, as does distance measurements. What changes is the understanding of the stability of a photon of light in a vacuum and the effect of this instability on travel time while passing near a gravitational well.

So while it's a photon of light, it travels light speed. When the energy converts to kinetic energy for a breather, it is affected by the gravitational pull, in a manner significantly stronger than a neutrino is affected. When it then flops back to being a photon, it is once again traveling at the speed of light.

What intrigues me about this is that this will also have implications regarding relativity, as every time the light flips state, it is essentially anchoring itself to a location in space from which the next photon flop can take its bearing. My mind can't quite grasp the further implications of this right now, but it could really mess with observation of light from a moving point (which all points are).

The recalibration is mostly on how we project distances based on light measurements; it's now become significantly trickier, as we need to account for gravity at specific moments.

What intrigues me about this is the how this provides a very *VERY* fine measurement of gravity and the probability of this decay occurring. Like woah.

Re:So, what's the correction?

[Anonymous Coward]

do they correct the idealized, or do they correct the observed?

Neither. You cannot correct the speed of light, because it isn't measured, it is DEFINED as EXACTLY 299,792,458 meters per second. So it is not the speed of light that needs to be updated, but the length of the meter.

Do you recognise your use of the English language is quite pathetic?

Idealized is not the correct word but Idealised is and meter is not spelled as meter it is metre.

With regret, the \s\n American's at dashslot will delete my post as they are loosing ground.

EOF && $printf end of slash\ /N dash *.* rm/rf.

Re:So, what's the correction?

[peawormsworth]

Then why dont we define the meter in terms of speed of neutrinos?

Don't mess with "c"

[NReitzel]

There's an alternative explanation. Space-Time could have non-zero viscosity, and slow down photons.

There are a lot of reasons to consider that space might have a viscosity. For one thing, it would neatly explain the expansion of the universe, without the necessity of invoking dark matter and dark energy.

We live in interesting times!

-- Norm Reitzel

Re:Don't mess with "c"

[Anonymous Coward]

Isn't this essentially what the article is saying -- that photons are slowed down by a "viscosity" that is relative to the mass of the galaxy? Since neutrinos don't interact with that mass, they are not slowed down by it.

They are definitely not saying that the physical constant is wrong, just that light doesn't always travel at that speed, even when in a vacuum.

dom

Re:Don't mess with "c"

[jovius]

Space has a sort of viscosity if it would mean gravity and expansion, but that doesn't have an effect on the speed but the frequency of a photon. So it's more like a spectral filter.

Re:Don't mess with "c"

[meglon]

No, it's saying that the photons travel at the speed of light, but are not always photons..... and when they're not photons, they travel slower than the speed of light.

Re:Don't mess with "c"

[Em Adespoton]

Based on this, I'd like to know what the distance spread is on the lifetime of a photon, and what affects this lifetime. Because we're obviously seeing state change as part of the energy transfer.

Re:Don't mess with "c"

[muridae]

It isn't a fixed length of time or distance (same thing at the speed of light in a vacuum, excepting spacial expansion). It's a statistical chance; each high energy photon has a chance at each and every point in time to split into an electron-positron pair (annihilation of the pair create gamma and higher photons, so it should only be those photons that split) and then those will travel for some time, being effected by gravity and all the other forces, before re-combining into a photon.

That's my complex way of saying "eh, I dunno, I got far enough in physics but that's above my head to figure out." If you want to understand the Schrodinger equation, or can find a Feynman diagram that lists the chance over time, good luck. I tried googleing phrases I thought would get me an abstract or brief but came up empty.

Re:Don't mess with "c"

[Em Adespoton]

Yeah; that's about how far I got... but "statistical chance" is just a handwavy method of saying "we don't know the full mechanism, but we can predict the frequency of the results."

If it's purely a case of, for example, the Higgs field state at that moment, then it would follow that SOME photons would travel the entire distance, and we should be able to measure that. In fact, there should be a fairly even distribution that should be measurable, representing the specific probability curve. However, if it's flat, that implies a definite lack of chance and some other unknown factor influencing the time/energy/location relationship of a photon.

These are areas that will likely be explored ad-nausea now that the underlying observation has been made. I'm interested in the results without having to be the one to do the work :D

Re:Don't mess with "c"

[Anonymous Coward]

It is wrong to think of it as the number of times it split into such particles. The basis for things like quantum field theory and propagation being affected by particles turning into other things is that the result of a particle moving from point A to point B is an average over every possible path it could have taken weighted by the chance of taking that path. This also includes the times it splits or splits multiple times. This sounds odd, but it has connections to he principle of least action in classical physics (kind of a path of least resistance) and idea from optics that amount to averaging over all paths a ray of light could have taken to get the result of how a wave of light would travel. But in QFT, these different paths all average together, so you can get that each individual particle follows the same path, each the same average of possible paths. Probability enters into it with changes in each photons path only with interaction with other outside forces or particles.

Re:Don't mess with "c"

[Bryan Ischo]

You're playing games with words. Viscosity is "a measure of its resistance to gradual deformation by shear stress or tensile stress, due to friction between neighboring particles that are moving at different velocities". How could any part of that definition have anything to do with light?

Or do you intend viscosity to mean "a force which slows down photons"? In which case your sentence is "Space-Time could have a non-zero force which slows down photons, and slow down photons", in which case you aren't really saying anything other than, "something could be causing these photons to slow down", which isn't actually saying an explanation at all given that the whole question is *why* these photons appear to be slowing down.

Re:Don't mess with "c"

[Anonymous Coward]

"There's an alternative explanation. Space-Time could have non-zero viscosity, and slow down photons."

That would suggest that the effect would be much stronger when viewing photons originating from further away since those photons traversed much much more space than the ones examined here.

Re:Don't mess with "c"

[Anonymous Coward]

that sounds complicated.

Why couldn't space itself have non-constant, non-gravitationally induced ripples to it? It'd be a fairly 'neat' solution to dark matter as well. We know the theortical math for gravitational effects needs adjustment on larger scale. We know much of it observes the same as gravitational effects anyway.

In nearly 15 years, I've never done this...

[bmajik]

FIRST POST

(however, the apparent local time when you see this post may differ based on the apparently non-constant nature of c )

Re:In nearly 15 years, I've never done this...

[Dins]

Maybe you should have stuck with not doing it. Just sayin' ;)

Re:In nearly 15 years, I've never done this...

[sammyo]

Perhaps you forgot to take into consideration the speed of light through fiber is less than c?

Re:In nearly 15 years, I've never done this...

[rsborg]

Perhaps you forgot to take into consideration the speed of light through fiber is less than c?

And the speed of light over Verizon fiber will vary based on whether it's sending Netflix photons or not.

Re:In nearly 15 years, I've never done this...

[Dancindan84]

If this joke goes over someone's head who's sufficiently dense, does that affect it's arrival time?

Re:In nearly 15 years, I've never done this...

[Ceriel Nosforit]

J.D. Franson's research appears to be Nobel prize worthy for its implications, and how much it could simplify our understanding of the universe. Wanting a first post on this is understandable.

Anyway, nothing 'virtual' at all about virtual particles. - Who would thought?

Re:In nearly 15 years, I've never done this...

[theskipper]

I'll let you know in a minute or two.

Re:In nearly 15 years, I've never done this...

[jdavidb]

Mod up to 6!

Re:In nearly 15 years, I've never done this...

[Anonymous Coward]

The Netflix photons may enter a photon trap and achieve a speed of zero if the Verizon data cap is exceeded. All of which are immutable laws of physics and in no way bear upon internet fast lanes. So say we all!

Re:In nearly 15 years, I've never done this...

[Thanshin]

Perhaps you forgot to take into consideration the speed of light through fiber is less than c?

So... it's b?

What did I win?

Re:In nearly 15 years, I've never done this...

[HybridST]

Hawking thought this when he discovered/derived Hawking radiation from black holes. "Virtual" particles popping into existance exactly at the event horizon. Rather than annihilating as such particles typically do, one falls in and the other is released from the black hole.

This is a somewhat simplified account but the realization of virtual particles has been "known" for a few decades. Search youtube for "Susskind Black Hole" for a lecture series, about 16ish hours of material on this phenomenon.

Re:In nearly 15 years, I've never done this...

[Anonymous Coward]

This is a somewhat simplified account but the realization of virtual particles has been "known" for a few decades.

Such a process of allowing virtual particles to become real particles has been known about since the inception of the virtual particle formalism. You just need a source of energy and momentum that allows for the virtual pair to persist without violating conservation laws. The process is the same for normal pair production when a high energy photon interacts with another particle allowing conservation of those values, or the inverse where a high energy particle interacts with a low energy photon (e.g. the GZK limit). Hawking's insight was to point out both the process and implications of that happening from interaction with a strong gravitational field.

Re:In nearly 15 years, I've never done this...

[Ceriel Nosforit]

Thanks for the tip on the video lectures! This might help me understand laser action on a much more fundamental level. =)

I actually did know about Hawking radiation... But I wish to add more nails to the coffins of outdated and poorly worded scientific names. Another source of annoyance for me is 'complex' numbers, which IMO would be better described as e.g. 1.5-dimensional numbers. - Thoughts on this?

Re:In nearly 15 years, I've never done this...

[Anonymous Coward]

Another source of annoyance for me is 'complex' numbers, which IMO would be better described as e.g. 1.5-dimensional numbers. - Thoughts on this?

Except that the complex numbers are a full 2 dimensional vector space. Historically, they were even used as 2D vectors before more modern vector notation was adopted (along with quaternions for 3D and 4D stuff).

And virtual particles are still quite virtual. They were know to have impact on real world measurements from nearly the start of their proposal, but they are distinct from real particles in interactions because of their ability to side step energy conservation in processes that allow them to be involved in interactions but not leave as long as they are not following conservation laws properly.

Re:In nearly 15 years, I've never done this...

[Ceriel Nosforit]

Since you're an AC I'll ask for references, or accuse you of trolling.

Re:In nearly 15 years, I've never done this...

[Anonymous Coward]

Page 4 (yes, right at beginning) of "Complex Analysis" by Joseph Bak and Donald Newman gives a low level introduction to the equivalence between complex numbers and 2D vectors. Also page 335 of "The Way of Analysis." Or you could just Wikipedia article on vector spaces which uses complex numbers as an example several times. Or if you don't like Wikipedia, here is a lecture that at the end lists complex numbers as vector space over R. There are more if you search via Google, although it is easy to get a lot of stuff for "complex vector spaces" which is a vector space over C, using complex numbers as its field (i.e. the number system for each component), which is different than the talking about the complex numbers themselves as a vector space of reals.

And if you didn't feel like looking at books or links, you can just look at the definition of a vector space itself and complex numbers become a trivial example: A set V (C in our case) and field F (R in our case) along with an addition and multiplication operation (just regular complex addition and multiplication in our case) is a vector space if: addition is associative and commutative (complex addition is both), there is an addition identity (0+0i in our case), an additive inverse (for every x in C there is a well defined -x), an identity scalar from F (1 in our case), scalar multiplication is distributive over vector and scalar addition (it is for C), and associativity of scalar multiplication (a(bx) = (ab)x for reals a, b and complex x). The dimensionality is just the size of the minimum basis set. A minimum basis set for C is just the set of 1 and i. This is a basis since you can express all complex number in terms of some real x and y with x+iy, and this basis is minimal since there is no non-trivial linear combination of basis vectors that can give you zero (i.e. there is no real x and y such that x+iy = 0 except for when both x and y equal zero). Hence the C is a vector space over reals with a dimension of 2.

Re:In nearly 15 years, I've never done this...

[Ceriel Nosforit]

That convinces me. Much obliged.

Thought I still want |z| to be thought of as potentially half-dimensional... :b

Re:In nearly 15 years, I've never done this...

[Anonymous Coward]

Vanilla 2D, 3D, 4D, etc. vectors have a magnitude too (4D ones in special relativity even have a negative sign in the norm). Vectors in polar notation using the magnitude to describe them still require the same number of components to fully describe them though.

Re:In nearly 15 years, I've never done this...

[Ceriel Nosforit]

I should explain, I'm being bullheaded about this since bosons have interesting behavior (e.g. laser action) because they lack charge. So much of our claims of understanding physics comes out of mathematical frameworks that my instinct for natural philosophy tells me that re-factoring old mathematics is a great idea to try.

I was watching a presentation by Susskind about black holes today and was rather confused about the holes he left in explaining the reasoning.
Primarily; he said you analyse a black hole by constructing it out of single bits of information. The idea to use a photon of the same size as the black hole is brilliant, but it ignores the elliptic polarization of the EM field of photons in free flight, and the example he showed an already existing large black hole on which he made just a single measurement. Extreme cases, like where the existing event horizon is around plank-length and the photon contained more energy than the known universe, was apparently ignored. He appeared to then conclude that photon energy vs. black hole growth was invariant from a single point of data...

After this, he concluded that a planar section of a sphere with plank thickness was 2-dimensional, and objected to the implications of the faulty reasoning. What I learned from this was that if we humans are so intent of mistaking the map for the terrain, then we need much better maps. 'Maps' here of course meaning mathematics.

Ummm

[NoNonAlphaCharsHere]

The electron-positron pair CAN'T travel at c, so there must be a deceleration when the pair is formed. Sure, when they recombine to become a photon again, they must (by definition) be traveling at c once more. So, by my thinking, either c varies with distance, or there's something wrong with this model. Could one of you astrophysics guys speak to this?

Re:Ummm

[mrsquid0]

Photons need to have gamma-ray energies before they can create virtual electro-positron pairs. Visible light simply does not have enough energy to do this.

Re:Ummm

[tpjunkie]

The time period over which pair production-annhilation occurs might be a small part of the correction here, but from my quick reading of TFA, I think the key phrase is "This results in a small correction to the angular frequency of a photon and thus its velocity," where velocity is the key word. Velocity of course is a vector quantity, consisting of both a speed (c) and a direction. The key aspect here is the direction; when the pair recombines, the total energy of the system is slightly different as the positron-electron pair is affected by gravity and thus may pick up a small positive or negative acceleration from the gravitational potential they are traveling through. When they recombine this will be reflected in the new velocity (c d) of the resultant photon, which is not exactly the same as the photon prior to pair production. At least thats what I got, but I'm the wrong kind of doctor to be an expert in this. Any PhD's wanna weigh in and correct me, please do!

Re:Ummm

[NoNonAlphaCharsHere]

1) Irrespective of frequency, my question stands. Electrons/positrons CAN'T travel at c, photons MUST. So EM radiation (happy now?) must travel like a dotted line.
2) We're talking about visible photons in this case, anyways.

Re:Ummm

[NoNonAlphaCharsHere]

Ahh. So you're saying it follows a zig-zag path. Now THAT makes more sense. So the TOTAL travel speed isn't c, just each individual leg of the journey is.

Re:Ummm

[shoor]

Ah, this is getting off topic, but your comment raised a question in my mind. Suppose the light is blue shifted for an observer approaching it so that it does have the energy to form an electron-positron pair, but for another observer not approaching it as fast, it doesn't have the energy. Might one observer see the pair formation while the other did not?

Re:Ummm

[TapeCutter]

It gets even stranger from the POV of the photon/neutrino. Anything travelling at the speed of light does not experience time or distance. As far as these particles are concerned they hit the telescope at the same time they leave supernova.

Re:Ummm

[Culture20]

I never saw light without not seeing the positron/electron pair formation. Ask Mr. Cat.

Re:Ummm

[muridae]

No, we aren't talking about visible photons. The emissions from the supernova were neutrinos and a gamma ray burst, the visible light travels still separately because of the other things in space that it interacts with that are transparent to gamma energy and above. But, yes, over the very large distances between us and the supernova it was not just a few photons that traveled at less than c for some time, but the chance rose high enough that it was nearly all of the photons.

All EM radiation travels at the speed of light. High energy photons can, briefly, become virtual particle pairs that do not travel at the speed of light. The article author noted that the chance, over the time and distance between us and this specific supernova, was high enough that it would account for all of the gamma ray and higher energy photons traveling as particle pairs for some part of their trip and that time would account for the known time delay. This only applies to gamma rays above (i think) 511 keV (one of the gamma rays emitted in an electron-positron annihilation. might need to be 1022keV for a single ray to form both particles from a single photon; ask a particle physicist, not a programmer like me). According to Alpha, a 500nm green photon has only around 2eV. Violet light gets up to 3 eV and a little higher; still not enough to create any particle. E=mc^2, so you need a good deal of energy just to create a very tiny electron.

Re:Ummm

[muridae]

Bloody good question. They are called virtual particles, though. If forced to answer, I would suspect that the energy added by the observer traveling fast enough to blue shift the light that far, 50,000 times the wavelength (talking about a 500nm green down to 10picometer gamma) and 50,000x to 100,000x energy in keV, would require a good portion of c and would reduce the apparent distance covered to a lower amount that does not offer a high enough chance of a virtual particle interaction.

But that's just me making stuff up and pulling a WAG.

Re:Ummm

[Ungrounded Lightning]

Photons need to have gamma-ray energies before they can create virtual electro-positron pairs. Visible light simply does not have enough energy to do this.

No, they don't

They need those energies to create REAL, PERSISTENT electron-positron pairs, which fly away and last until they interact with something else - maybe centuries or eons later - that changes them to some other particle.

Virtual particle pairs, as long as their lifetime is less than a time that puts the product of the "error' in energy with the lifetime of the error under the uncertainty principle limit, can be created by photons that are far too small to create free particles. In fact, if the lifetime of the virtual particle pair is short enough, you don't even need the photon.

Re:Ummm

[muridae]

That's what the article seems to suggest, yes. And that the virtual particle pair, if they exist for real time, would move at less than c for their short life-span. But the major change from Earth's perspective is that the gamma rays we saw did not travel in the straight line that the neutrinos did.

That might also explain the second neutrino burst (maybe, wild guess from a programmer). If some of the neutrinos went through a virtual particle state (Z boson, I think?) then they would also arrive at a different time. That would account for neutrinos that made the trip with no virtual particles, those that slowed down due to the mass of Z boson interactions, and, according to the research summarized in the article, all the gamma rays that went through a virtual particle phase and dealt with gravity. If it all works that way, it would be beautiful science explaining more things we thought we understood. Ahh, science!

Re:Ummm

[Anonymous Coward]

I asked a physicist about this recently because it really puzzled me how a photon could seemingly not experience time, and I wondered how it might be connected to the ideas about quantum communications using entangled photon pairs (i.e. explain spooky action at a distance by talking about how the photons involved experienced no time since they split from each other).

His dumbed-down explanation to me (which I might have misinterpreted or misremembered by now!) was that this was all a very naive way of looking at things. It's not that, from a photon's perspective, time is instantaneous and you're everywhere you'll ever be at once. It's more like time doesn't exist as a valid concept for a photon; it just doesn't make sense to talk about a timeline for a photon's frame of reference in the same way that it doesn't make sense to ask what the color red smells like. Photons *do* experience casual, discrete physics events as separate events on a timeline of sorts, happening in the correct sequence. If a photon bounces off one object then later bounces off another those things happen in a correctly-defined order such that the result of the first interaction can affect the probability of the occurrence of the second.

Re:Ummm

[Anonymous Coward]

A high energy photon will not spontaneously turn into a normal electron and positron, because such an interaction cannot both conserve energy and momentum. It must interact with another particle in order to allow conservation of energy and momentum. It also then doesn't matter what frame you are in, as it then depends on the relative velocity of the photon and the other particle it interacts with. While observers might see different dimensions and values for measurements, under relativity they can't disagree on more fundamental things like the count of something.

Re:Ummm

[Anonymous Coward]

(i.e. explain spooky action at a distance by talking about how the photons involved experienced no time since they split from each other).

Although the same entangling phenomena can happen to electrons and other particles though, so it isn't something specific to a photon's speed.

Re:Ummm

[Anonymous Coward]

The definition of c under quantum field theory is the speed of light as measured in an ideal vacuum (i.e. with virtual pairs, but no other real particles). This already takes into account the time it spends as virtual pairs of massive particles. So by just turning into massive particles, that does not make light slower than c. The difference here, and for a lot of other effects involving virtual particles, is when there is an outside force or particle that interacts with that virtual pair in transit. A gravitational well (also analogs for electromagnetic fields) can interact with that virtual pair and then impact the speed. So if you had a photon in a huge empty universe in a sense, it would still travel c, but as soon as it has to pass galaxies and junk, that changes a very tiny bit (and much more so if it has to go through stronger junk, like a strong magnetic or electric field).

Re:Ummm

[Anonymous Coward]

High energy photons can, briefly, become virtual particle pairs that do not travel at the speed of light

Photons of any energy can turn briefly into a virtual pair of electrons and positrons, as the virtual processes play funny games with conservation of energy. That is separate from the process of high energy photons turning into a real particle pair, which doesn't happen in transit through vacuum, but only when interacting with an outside particle (a photon by itself can't split into two massive particles while conserving both energy and momentum). The propagation of all photons takes into account the virtual pair production though, and c is the speed after that has been factored in. What is not factored in is if any outside stuff interacts with that brief virtual pair.

Re:Ummm

[Anonymous Coward]

As explained in other posts, you need a second particle to interact with the photon to get pair production, so the relative speed between the photon and other particle is what matters. That said, you can have cases of particles going so fast, that the very low energy photons of the cosmic microwave background blue shift enough to produce electron-positron pairs, or pairs of pions. The latter case sets up kind of a rough upper bound on the highest end of cosmic rays, as anything going faster than that will essentially be decelerated by the CMB over some intergalactic distance.

Re:Ummm

[Andy_R]

That all makes sense, but it doesn't seem to match up to the observations.

The article says neutrons were observed arriving hours before optical photons, but what you are saying is that photons of high enough energy to become temporary particle pairs should arrive later than lower energy ones, which don't get slowed down by temporarily dropping below c.

If the chance to become a particle pair varies with energy, we ought to see the supernova change colour, starting off shining brightly in the visible spectrum only, then gradually becoming bright at higher and higher energies, as higher energy photons emitted at the same time as lower energy ones arrive progressively later on.

Re:Ummm

[Anonymous Coward]

Physics classes push the difference between "speed" and "velocity" pretty heavily to make sure students understand the difference between a scalar magnitude and a velocity. But if you talk to actual physicists, they get pretty sloppy with the two words. In this case, the paper seems to suggesting an actual change in propagation speed, and not just a zig-zag or change in direction of travel.

Re:Ummm

[Anonymous Coward]

That's what the article seems to suggest, yes.

The article makes no mention of changes in direction, only change in straight-line speed.

If some of the neutrinos went through a virtual particle state (Z boson, I think?) then they would also arrive at a different time.

Such effects would impact the speed of all neutrinos following that path, so you would not get two bursts. The paper attributes the two bursts to models of fast rotating starts capable of having two collapses before a large amount of light penetrates the upper layers of the star.

Re:Ummm

[Anonymous Coward]

Neutrinos oscillate through their electron, muon, tau manifestations so they have some sense of time as they travel very near the speed of light. We know they do this faster than the time it takes them to reach the earth from the sun (~8 mins), so we are talking minute time frames. Given the 168,000 light year distance to the 1987a super nova, we find that neutrinos would experience 88 billion or so state change events over this distance.

Re:Ummm

[mestar]

"It's more like time doesn't exist as a valid concept for a photon; it just doesn't make sense to talk about a timeline for a photon's frame of reference in the same way that it doesn't make sense to ask what the color red smells like."

Why do you use this stupid metaphor that does not add anything at all?

Re:Ummm

[mestar]

"Physics classes push the difference between "speed" and "velocity" pretty heavily"

You mean, bad physics classes...

Re:Ummm

[Anonymous Coward]

It is an actual distinction that I've seen people called out for messing up by paper reviewers for getting too loose in formal writing. Informally physicists can figure out from context what was meant, but that is not always clear to students, and also graders trying to judge what students mean. There are several ideas in intro physics courses that terminology is kept strict to help differentiate ideas, some of which are more important than the terminology itself. Bad classes are the ones that go too far and teach things like centrifugal force doesn't exist (but I've seen ones that merely point out to be careful or avoid centrifugal force references without further thought result still in students coming away with the idea that it doesn't exist and people should hypercorrect references to it).

Re:Ummm

[minogully]

So, if this proposed effect can happen to visible light. Could the idea in this article be an alternative explanation for how gravity effectively "bends light"?

(I'm not a physicist, so sorry if this sounds stupid)

Re:Ummm

[Anonymous Coward]

Nope. There's quite a significant difference between speed and velocity, which he accurately explained. Velocity is a vector consisting of both speed *and* direction. Since velocity requires a direction, and speed does not provide one, they *cannot* be the same thing.

Re:Ummm

[mestar]

That's a strange distinction you are making there. I think your teacher was more focused on memorization of stupid definitions, and less on understanding.

Re:Ummm

[Anonymous Coward]

(Not the same AC) That distinction is near universal in physics textbooks, and is not a quirk of a handful of professors. When introducing vectors, a conceptual point is made about the difference between scalar and vector values. That particular example of terminology is used to point out the difference between a vector and its magnitude. For whatever reason, possibly just common use, the magnitude of velocity has a special name, but it serves a pedagogical use in the end. I've seen this as an aspect of physics education as an undergrad, when TAing in grad school, when teaching, and in discussion with people involved in physics education at multiple universities (including both in North America and Europe).

At the higher levels the distinction doesn't matter too much when it is pretty obvious something is a vector or not. But there are a few cases where it can be important, e.g. the Maxwell-Boltzmann distribution of velocity vs. the Maxwell-Boltzman distribution of speed, where the former has an average value of zero but the latter does not.

Re:Ummm

[Anonymous Coward]

Probably not, although hard to say. Quantum field theory is based on special relativity, where space if flat, so would not be addressing the effects of curved space time where photons are not bent because they are being pulled, but be cause the idea of what is a "straight line" in curved space has a bend in it. And as proposed it doesn't involve any bending, although an extension of the idea (it is kind of half-assed as is) might be able to come up with something like bending light.

Consider the source

[oldhack]

It's a Medium piece. Rest assured it's a bullshit click bait.

Basic premise verification

[ipsender]

What is the evidence that the process which produces the neutrino flux is contemporaneous with the process which produces the light burst in a collapsing star?

Re:Basic premise verification

[Anonymous Coward]

And how do we even know they came from the same source? All these assumptions! /s

In nearly 15 years, I've never done this...

[Anonymous Coward]

I read some of the article*, it didn't sound like 'c' was changing. You just shouldn't try to make your first post over large distances of space.

* Disclaimer: I am not a physicist.

More or Less Exactly

[Anonymous Coward]

More or less exactly....

I loled

What the hell...

[Chocolate Teapot]

...is "more or less exactly" ?

Re:What the hell...

[The Grim Reefer]

It's difficult to explain as it's a fuzzy thin line. ;-)

Re:What the hell...

[new death barbie]

"more or less exactly" == "approximately", more or less exactly.

Re:What the hell...

[Anonymous Coward]

"more or less exactly" == "approximately", more or less exactly.

I see. Clear as mud now, but perhaps you could crystallize that viewpoint by overlaying this on the Western Scale of Best Guesstimates.

It seems to hold slightly better accuracy than the previous standard scale of SWAG or the CloseEnoughE-Meter.

Re:What the hell...

[excelsior_gr]

It is almost precisely what you make it to be.

Re:What the hell...

[geekoid]

It means their are error bars due to the limitation of the equipment and new equipment might change the answer at some decimal point down the line.

Example:

On my birthday I will be more or less 50. So if its before 4AM, in general parlance, people would say I"m 50 and they would more or less be exact. But if you accurately look at it I would actually be 50 until 4AM

Re:What the hell...

[Khashishi]

It means the reporter was lazy.

Re:What the hell...

[Chocolate Teapot]

That's what I first though. Nice to know I was precisely in the same ball park as you.

Re:What the hell...

[Anonymous Coward]

It means more exactly, or less exactly, or both.

What gets corrected?

[Russ1642]

Presumably this happens all the time for light so what we've measured as the speed of light is correct, it's just that the true universal speed limit is higher and only neutrinos travel that fast. So we should find out that speed and use the speed of neutrinos when doing relativistic corrections.

Re:What gets corrected?

[Charliemopps]

Presumably this happens all the time for light so what we've measured as the speed of light is correct, it's just that the true universal speed limit is higher and only neutrinos travel that fast. So we should find out that speed and use the speed of neutrinos when doing relativistic corrections.

But we are pretty sure neutrinos have mass now... so nope.

Re:What gets corrected?

[Anonymous Coward]

It's more complicated than that:

Neutrinos are suspected as having rest mass (albeit very, very small) so they can't quite hit "the speed of light in a vacuum", c, (or more properly c0, where just plain c is the speed of light in a medium). So, we can't use the speed of neutrinos as the absolute speed limit.

Now, what is being said here, is that, over vast distances, the combined effects of gravitation fields and the probabalistic generation and recombination of virtual particles create an observed "speed of light in a medium" effect upon the observed photons, which is itself lower than the almost-c0 of the neutrinos that were produced at the same event as the original photons. The absolute speedlimit over "short" distances is unaffected.

Re:What gets corrected?

[Anonymous Coward]

That's not what this is. The article is misleading. What's happening is that a photon is splitting into a virtual particle pair, which is not light anymore, and is not traveling at C. When the pair recombines into a photon, we have C again. This 'correction' is to correct the average velocity of light over great distances. Neutrinos are constantly moving at C, since they aren't interactive in the same way that photons are.

Re:What gets corrected?

[Anonymous Coward]

Our local measurements of the speed of light are not affected by this, because the pair formation is not frequent enough to affect experimental measurement. A few photons in the pack emitted in an experiment might undergo it, but the majority won't and we end up measuring the speed correctly. But over 168,000 light years, all of the photons undergo it sufficiently to delay the entire aggregate to the tune of 1.7 hours. What needs to be corrected is to take account of this phenomenon when calculating actual distance light will travel in astronomical scales. But not the value of c.

Re:What gets corrected?

[muridae]

c doesn't get corrected. Our measurement of the path that the light took gets corrected, as the virtual particle pairs interact with all the forces that photons are less affected by because of speed.

Re:What gets corrected?

[muridae]

Yup, it only affects a small percentage of photons for a very brief time. Schrodinger's equation and the rest of QED let you work out how many photons in a given burst over X amount of time. For most of our observations, in laser labs and other 'short' distances the effect shouldn't even be noticeable. But it might change astronomical measurements by a good bit. (well, 1.7 hours over 168,000 years, 1x10^-9; more or less, since light-years traveled and years traveled aren't identical at that distance due to expansion effects)

And if it affects photons, it will affect other particles as well. Maybe it explains the two neutrino bursts; if one burst traveled in a straight line and the other had a virtual particle interaction.

Re:What gets corrected?

[Anonymous Coward]

Yup, it only affects a small percentage of photons for a very brief time

That is not how virtual pair effects work in general, nor is it what the effect given in this paper say. The same effects would happen on Earth, except that the gravitational potential of Earth is smaller than that of the galaxy, as addressed in the paper. The effect for something coming from outside the galaxy would be four orders of magnitude larger than on Earth, while the effect on Earth would be smaller than the uncertainty in c was before it was defined as a certain number. Regardless, if this paper is correct, the effect on Earth have would just be incorporated into the defined value, as in we never saw/measured c without the effect except when looking into space.

Re:What gets corrected?

[mestar]

You never know the path of the photon. In fact, it looks like it went trough all the possible paths, including all the splittings and merging. You can not even tell if it went in a straight line or not.

Or Change the Theory

[Anna Merikin]

This could lead to the acceptance of alternative cosmologies that have been bubbling up for years. Try these links:

http://www.dailygalaxy.com/my_...
http://vixra.org/pdf/1404.0123...
http://www.researchgate.net/pu...

Re:Or Change the Theory

[MightyMartian]

Or it could be a badly written summary and article that completely misrepresent what is being stated.

If every science journalist on the planet were to spontaneously combust, not only would it introduce a whole new physical phenomenon, it would cause the average IQ of the planet to jump by at least 5 points.

Re:Or Change the Theory

[meglon]

What could lead to the acceptance of an alternate cosmology is when one of them is more refined than Relativity. So far there's a lot of BS out there, but nothing coming close to Relativity.

I'll at least give you points for not putting up a link to that Plasma Cosmology bullshit.

Re:Or Change the Theory

[hsthompson69]

I'm shocked. We completely agree on this one. :)

Re:Or Change the Theory

[fibonacci8]

Or the average IQ would remain 100, since it's a fixed number.

Re:Or Change the Theory

[Bob the Super Hamste]

It would go up but would be re normalized in several years.

Finite chance?

[wisnoskij]

What is a finite chance?
For that matter, what is an infinite chance?

Re:Finite chance?

[Russ1642]

Wait until you see these guys split up a bill for lunch.

Re:Finite chance?

[Overzeetop]

I'm not sure, but it may or may not involve monkeys, typewriters, and the works of Shakespeare.

Re:Finite chance?

[geekoid]

Given a specific period of time it WILL happen.

Given all time and space it might happen. Also: given a sub set of infinity it MAY happen within that subset but WILL happen in a larger subset of infinity.

Re:Finite chance?

[wisnoskij]

Will Happen? So take any two point in time, no matter how short apart, and it WILL happen in between these points? So "finite chance" means that it is constantly happening?

Re:Finite chance?

[wisnoskij]

Or Finite Chance = x% chance of happening for any instant as x approaches 100. So it is not guaranty given infinity, but for most intents and purposes it is a 100% chance? Infinite Chance = x% chance of ...... as x approaches 0. Basically never happens, but give infinity it is a possibility.

Re:Finite chance?

[Anonymous Coward]

When discussing probability, finite means non-zero and non-infinitesimal. Infinitesimal is not a finite value either, and an infinite probability makes no sense... so finite in terms of probability is the opposite of infinitesimal.

Re:Finite chance?

[sexconker]

No it doesn't. Finite means finite.
Chance ranges from 0 to 1. All numbers between 0 and 1 (inclusive) are finite.
All chances are finite.

Re:Finite chance?

[Anonymous Coward]

All real numbers between 0 and 1 are finite, and an infinitesimal is by definition not a real number. Infinitesimals can be expressed in transfinite number systems, but you are no longer limited to just finite numbers. The expression "finite chance" is very common in both physics and math, and at least less confusing than the formally defined "almost nowhere" and "almost never."

one part in 200,000,000

[peter303]

Distance to Magellanic Cloud (158K LY) divided by 7.7 hours. Light travels 300,000,000 meters a second. So that would be a delta of a couple feet per second. I'd think we'd see something large in our solar system.

Now we know everything?

[NMBob]

So I guess there's no question that we know every detail of what happens as a star is collapsing and that the photons didn't just take longer than we think they should to make their way out? And, also, wasn't this optical photons they were looking for? What if there was a brightening, but below the threshold of the detectors? If it's radio/X-rays/etc. then see the first sentence.

Even that Sounds Wrong

[Roger W Moore]

The photons still move at 2.99x10^8m/s. It's the electrons and positrons that move slower.

This whole premise sounds wrong and needs data to confirm it. The problem is that the article is wrong to claim that neutrinos move at the speed of light - they have a non-zero mass and so must move slower than this. However their mass is incredibly small (probably ~100,000 times less than an electron - so small that we have not actually measured it yet!) so they move very close to the speed of light. What sounds dodgy is that they are claiming that the primary effect of the non-zero neutrino mass is negligible while the secondary effect of the zero-mass photon coupling to virtual electron-positron pairs is more significant. A quick back of the envelope calculation suggests that the neutrino mass could cause a ~30 minute delay in the neutrino arrival over such a distance.

In addition they are basing this on being able to accurately calculate the scattering delay time of photons in a super nova. Less than a decade ago super nova models could not even get the star to explode (the explosion was not powerful enough and was overcome by gravity) so I have a hard time believing that they have perfected things to the extent where can really give a reliable number for the scattering delay time.

As usual extraordinary claims require extraordinary evidence and so far there is much of the former and none of the latter. Although it is also possible that the article is completely misrepresenting the claims but if so it is doing an even worse job of it that you suggest!

Re:Even that Sounds Wrong

[jae471]

I am not a particle physicist, so I cannot comment as to how many vacuum polarisation events a single photon would undergo during the 168000-year trip, nor how much this would actually affect the average transit time. And I agree that this claim seems off -- especially since a photon takes ~4000 years, give or take an order of magnitude, to leave the center of our sun, which has a lower density than what is present in a core-collapse supernova.

OTOH, this is an interesting idea, and it may have greater implications in cosmology.

Re:Even that Sounds Wrong

[pla]

The problem is that the article is wrong to claim that neutrinos move at the speed of light - they have a non-zero mass and so must move slower than this.

I suspect the actual study, if not TFA, took that into consideration.

I actually find it more odd that the effects of mass on the neutrinos slowed them less than the effects of quantum gravity on the photons - The photons still lagged the neutrinos, rather than making up for a mere three hours' lag on a journey of 168,000 light-years? Truly mind-boggling! Kinda like driving from NYC to LA and still beating a flight that transfers at every airport on the way.

Re:Even that Sounds Wrong

[Anonymous Coward]

1) What about photons emitted from the surface? Wouldn't the rapid change in velocity of the material emit intense radiation?
2) When the star rebounds after collapse, isn't that another opportunity for many more photons to escape, not just from the surface but from the ejecta?

The collapse and rebound happens in a matter of milliseconds, right?

Re:Even that Sounds Wrong

[angel'o'sphere]

You are mixing up rest mass (which neither the photon nor the neutrino has) with moving mass / impulse, which the photon has and the neutrino 'perhaps' has.
You claim that a neutrino has always mass (or more than a photon) is either plain wrong or grants you a noble prize if you can proof it.

Re:Even that Sounds Wrong

[Anonymous Coward]

The surface mostly doesn't find out about the explosion from the core collapse until the electromagnetic force has had a chance to propagate to the surface, i.e. the huge burst of light. Until that light gets to the surface, since the neutrinos mostly don't interact with it (enough due to heat the surface, but no where near as much as the soon to come photons), the surface isn't emitting any where near as large amount of light until the outward part of core collapse get there. The collapse of the core takes on the order of milliseconds, but that isn't the whole star, only the inner part, and the time it takes to propagate out of the star is on the order of hours.

Re:Even that Sounds Wrong

[Anonymous Coward]

As long as neutrinos have been known about (and even when just a postulation) they had moving mass, as they carry energy away from decays and reactions. There was never any doubt in this, otherwise they would not carry any momentum or energy. The observation of neutrino oscillations is what now supports the ideas that neutrinos have rest mass. Short of some very esoteric theories to explain how the neutrino can oscillate without rest mass, it is pretty well given it has a rest mass.

Re:Even that Sounds Wrong

[Anonymous Coward]

It was shown that neutrinos have rest mass in 1998 when the Super-Kamiokande detector showed solar neutrino oscillation: http://arxiv.org/abs/hep-ex/9805021.

Re:Even that Sounds Wrong

[Anonymous Coward]

The collapse of the core takes on the order of milliseconds, but that isn't the whole star, only the inner part, and the time it takes to propagate out of the star is on the order of hours.

So, the difference between the neutrino observations and photon observations on earth?

Re:Even that Sounds Wrong

[Anonymous Coward]

As said in the summary, current estimates on how long it would take for light to get through those upper layers is on the short side, 3 hours instead of the 4.7 or 7.7 (depending on how you interpret the bursts). The author of this paper noticed the effect he calculated fit pretty closely with that missing time, although acknowledging that it is a simplification and a more careful calculation needs to be done and the time it adds to the light delay might just work out as a coincidence with that measurement.

Re:Even that Sounds Wrong

[Anonymous Coward]

photons don't take 4000 years to exit the core of our sun. photons get absorbed and emitted by mass in the sun, and there's some time between those two events. It's not "the same photon" that takes 4000 years. It's the energy in that photon. It's one of the stupidest things we say in college classes. The point is that the sun is very dense, but we fail miserably at getting that point across with the "photon" example. It's not even a stimulated emission, it's just energy.

Re:Even that Sounds Wrong

[Anonymous Coward]

Your information is out of date. Neutrinos have been know to have mass for over a decade. See e.g. http://en.wikipedia.org/wiki/Neutrino#Mass

No Nobel prizes have yet been awarded.

Re:Even that Sounds Wrong

[Anonymous Coward]

The scattering of photons within the Sun is dominated by elastic scattering (Thomson scattering), which is basically scattering of photons off of free electrons like billiard balls. Whether you want to view it as mechanical scattering exchanging momentum and energy, or the electron instantly absorbing and re-emitting the photon with a Doppler shift, it works out the same and physics doesn't distinguish (in the same way that a collision between two electrons doesn't distinguish which is which). But there is no time between the photon being absorbed and emitted, there is no time where the photon doesn't exist, as that such an interaction between just an electron and photon would violate conservation of momentum and/or energy. For such interaction, you need a third particle to be involved, which makes such interactions less common, but they do allow things like a photon to split into two lower energy ones. While a single photon won't survive all the way to the outside of the sun, most of the time is spent bouncing around like a billiard ball and can't be definitely described as being destroyed and created in the process.

Re:Even that Sounds Wrong

[Anonymous Coward]

A phpton might need 4000 years to get out from the sun's core - because the rest of the sun is in the way. A supernova doesn't have such problems. Supernova core photons are liberated as the supernova blows itself apart - all those trapped photons get out when the barrier layers are shredded and scattered.

Re:Even that Sounds Wrong

[Anonymous Coward]

IANAP, but as I understands it the argument that neutrions must have rest-mass is based on the observation that there is equal amounts of the three types of neutrions. Since there should be an overabundance of electron-neutrions, it has been argued that the neutrino cycles between the three types. However, to be able to do that it must experience time, which it can't do if it has no restmass and moves at light-speed.

Re:Even that Sounds Wrong

[david_thornley]

Note that massless particles, like the photon, can carry energy and momentum. They have to travel at the speed of light to do it.

Re:Even that Sounds Wrong

[Anonymous Coward]

That comment was in reply to someone incorrectly claiming that up until recently neutrinos were thought to have no rest or relativistic mass. Anything that carries momentum and energy has relativistic mass, and that despite neutrinos being thought to have zero rest mass for most of the history of neutrino research, they've always been considered to carry momentum and energy. The rest mass is the only part that has changed in recent terms, and the poster angel'o'sphere was flat out wrong about things in both cases.

Re:Even that Sounds Wrong

[Roger W Moore]

As long as neutrinos have been known about (and even when just a postulation) they had moving mass, as they carry energy away from decays and reactions.

Actually that is not true. The Standard Model originally had them with zero mass. This was disproven in 2002 by the SNO experiment which conclusively showed that neutrinos from the sun changed flavour which meant that they had to have a mass. The SuperK experiment also had some earlier results with atmospheric neutrinos which also suggested flavour oscillations. You are also under the misconception that mass changes with speed: it does not and is an invariant quantity the gamma factor in momentum comes from the velocity changing under relativity not the mass.

Re:Even that Sounds Wrong

[Roger W Moore]

That paper shows the solar neutrino problem not flavour oscillations. SuperK saw the first hints of this from atmospheric neutrinos, not solar neutrinos. However SNO was the first experiment to conclusively prove oscillations: they showed that the total flux of solar neutrinos was as expected but that only ~a third of them were electron neutrinos despite the fact that all of them started as electron neutrinos. Seeing a disappearance of a particular flavour does not prove oscillations: they might have somehow decayed or been absorbed through unknown processes. While this requires new physics neutrino oscillations was also new physics at the time so Occam's razor can not really pick between them.

Re:Even that Sounds Wrong

[Anonymous Coward]

"moving mass" here is being used for poorly named relativistic mass, which is not an invariant. For both gravitational and inertial purposes, things act like their relativistic mass in a given frame, regardless of what their rest mass is. Pedagogical arguments about the concept of relativistic mass aside, this chain of comments is clearly in response to someone separating rest mass from relativistic mass (calling it moving mass though), incorrectly said that they don't have rest mass even in recent understanding, and incorrectly said they used to not have any relativistic mass, which is clearly wrong as they carry momentum and energy.

Cannot read article

[Anonymous Coward]

Crappy medium.com presentation is crappy. No, I don't have a tablet, making their website unusable to me. Bit of the wrong way around, no?

Re:Cannot read article

[Goaway]

What part of the site needs a tablet?

Is it possible?

[TsuruchiBrian]

Is it possible that they just misjudged the distance between the earth and the supernova by 4.7 lighthours?

Re:Is it possible?

[Anonymous Coward]

That would be irrelevant. The particles under consideration all traveled the sameish distance, so the travel delay for both groups would be the same.

Re:Is it possible?

[Anonymous Coward]

No no no.

The point is that the neutrinos and the photons should be traveling at the same speed through space, regardless of the distance from earth. The neutrino just got a 3 hour head start.

The 3 hours is the calculated number for photons to diffuse from the beginning of the supernova event through all the material.
Once a photon gets out into empty space, it should be traveling at the speed of light in a vacuum, lock-step with the neutrino, never gaining or losing distance.

What is being posed is that even in the vacuum of space, a photon particle travels straight-line slower than a neutrino because of influence of gravity, and it matters over galactic distances.

What makes it confusing is the terminology. A photon itself doesn't travel at less than the speed of itself... but given a galactic-scale distance to travel, a photon sometimes briefly morphs into something else, then goes back to being a photon. While it's morphed (something made it do that), it travels slower than the speed-of-light constant.

Re:Is it possible?

[Anonymous Coward]

The particles under consideration all traveled the sameish distance

Proof please.

Is there a 'less nerdy version'?

[Voyager529]

Genuine question - this seems like an interesting thing, but as someone whose expertise in physics is incredibly limited, is there anyone who would be willing to provide an "explain it like I'm five" version for an individual like myself who is interested in understanding the speed differences observed in the particles?

Thanks, internet!

Re:Is there a 'less nerdy version'?

[suutar]

photons and neutrinos both travel at approximately the same speed in vacuum - "the speed of light"
However, when it comes to going through a non-vacuum, like a star, neutrinos have a straight shot because they don't interact with anything and the photons have to run through a pinball game (or a pachinko game, if you've seen those) until they actually get out. Best estimates of the time difference to date are about 3 hours.
Because of that, they would expect to see the light about 3 hours after seeing the neutrino burst, but in this case it looks like it was 7+ hours instead.
This guy (if I'm understanding it right) is saying that even "in a vacuum" light does enough zig-zagging to add a few hours to the transit time of a 163000 lightyear trip.

Re:Is there a 'less nerdy version'?

[Anonymous Coward]

Sure. Reddit will explain things like you're five. They have a whole subforum dedicated precisely to that. This is Slashdot. This is news for nerds - not for you. Don't let the door hit you in the ass on the way out.

Re:Is there a 'less nerdy version'?

[Theaetetus]

Genuine question - this seems like an interesting thing, but as someone whose expertise in physics is incredibly limited, is there anyone who would be willing to provide an "explain it like I'm five" version for an individual like myself who is interested in understanding the speed differences observed in the particles?

Thanks, internet!

Neutrinos go straight from start to destination, while photons have to take breaks every few minutes to pee, get a snack, fill up the tank, check out that yard sale, etc. They're like the cousin with ADD.

Re:Is there a 'less nerdy version'?

[geekoid]

"explain it like I'm five"

Because I said so.

Done.

haha, no I've never said that to my kids. I always followed the why question as far as I could. And when I didn't know, the internet did.

Re:Is there a 'less nerdy version'?

[jasax]

Unless between us and the supernova is some "dark matter" :-) (or something alike) that caused the photons to have the extra delay :-)

Indeed nobody has examined yet, IMHO, the path between us and the SN1987a supernova. Or even its "surroundings" when it was forming: did space time deformation or any other mysterious event occurred?

And if in general science often new knowledge erases old "facts", in Astronomy and Astrophysics that happens almost every day. So we have to take all this novelty with a grain of salt... (remember the recent flop of the particles travelling between CERN-Geneva and Grand Sasso...)

Re:Is there a 'less nerdy version'?

[muridae]

I'd correct the photon "zig-zagging".
The guy is saying that we know photons can very quickly turns into an electron and it's friend a positron. They almost instantly turn back, but since the electron and it's friend are bigger and heavier than a photon of light they are affected by gravity more.
So, if the author is right, the light we saw took a different path to get to us. Just a little bit different, enough to add an hour over the course of 163,000 years.

Re:Is there a 'less nerdy version'?

[Kjella]

The first part you got right, the second I don't think so. From what I gather the photon is really like an "on and off again" couple, every so often they split apart to an electron and positron but almost instantly realize being on their own doesn't work so they get back together again. But in those brief moments they're single they're pulled much stronger towards parties, curving the path they take between our house and their house - not zigzagging.

Apparently over a 168000 light year stretch this adds up to a 0.0005 light year detour, they've not traveled as straight a line as the neutrinos have. Of course we already knew gravity bends light, but these quantum effects means it bends a little more than expected from the photon's mass. It's no wonder quantum mechanics can drive you crazy, God isn't just playing dice on top of that the dice morphs between 1d6 and 1d20 during the throw.

Re:Is there a 'less nerdy version'?

[Bryan Ischo]

In this explanation, why is there a net gravitational pull away from Earth? In those brief moments where the photons disassociate into electron/positron pairs, why are they pulled in any direction in particular? Why are they more likely to be pulled in a direction that slows them down rather than speeding them up?

Re:Is there a 'less nerdy version'?

[Bryan Ischo]

Why is the force of gravity pulling these electron/positron pairs away from Earth? Why is there any net effect at all? Is there "more stuff" on average on the other side of that supernova than on this side?

Correspondingly, if a supernova were to happen here and direct photons in the other direction, would the light get there "faster"? If not, why not? Why is the net drag caused by gravity always away from the direction that the light is travelling?

Sorry if this is a double-post, Slashdot eats my comments sometimes, I swear.

Re:Is there a 'less nerdy version'?

[Neil Boekend]

They are sometimes pulled faster, sometimes pulled slower. Most likely these effects are just about equal.
The delay is from the pair being pulled up, down, left and right. That makes for a longer path.
The effect is minute, because most of the time even the main gravitational pull is really really small (there isn't much of anything between galaxies). Think "not even a millionth of what we often call "zero gravity" such as in the ISS".
However, over a distance of 168000 light years even these minute detours add up to a detour of 4 light hours.

Re:Is there a 'less nerdy version'?

[epine]

Apparently over a 168000 light year stretch this adds up to a 0.0005 light year detour

After scanning TFA, the first thing I looked up was the distance to SN 1987a, which the author somehow regarded as beneath notice. Perhaps he was preoccupied with the correct keyboarding of "orthopositronium".

Call me old fashioned, but I think that a person bleating away about an esoteric footnote of astrophysical revelation ought to first muster basic magnitude mastery.

Re:Is there a 'less nerdy version'?

[Bryan Ischo]

That doesn't make any sense to me. Any pull that has any component other than directly and exactly away from Earth would bend the direction of the light so that it completely missed Earth. Even the tiniest deviation thousands of light years away would cause the light to miss Earth by a huge, huge distance.

Or is the light somehow being pulled into a different direction and then pulled back on course to aim directly at Earth? How in the world would that work?

Re:Is there a 'less nerdy version'?

[painandgreed]

Unless between us and the supernova is some "dark matter" :-) (or something alike) that caused the photons to have the extra delay :-)

*cough* It's called "dark" because it does not interact with EM radiation, ie photons. Gravity from the dark matter will affect the photons, but as in the rest of gravity of the originating galaxy itself, will just cause a shift in frequency not velocity.

Re:Is there a 'less nerdy version'?

[Anonymous Coward]

The poster you are replying to is incorrect about the effect discussed in the paper here being about bouncing back and forth and taking a longer path to get from there to here but at the same speed. Regardless, if that were the mechanism, we would still get plenty of light because the original supernova sent out a lot of light in every direction. If some process bent or mildly scattered the light, we would still get some, just the stuff that would have missed before now hits us. It is like spraying someone with a hose using a wide spray in a light breeze, the drops might get deflected slightly, but the person is still going to get soaked.

I AM SO SMART. S M R T...

[Anonymous Coward]

I only understood this because it was explained on Cosmos.

subject

[Charliemopps]

Based on the last 100 crackpots that said the speed of light was wrong... or that it was variable...
and that I've never heard of this guy, and no other physicists are talking about this that I can tell...
I'm calling bullshit.

Maybe I'll feel dumb tomorrow, but I'm pretty sure physics blogs would be exploring right now if this were even remotely true.

also, this is just a blog post...

Re:subject

[doctor_subtilis]

Read it again because they are not saying speed of light is wrong. Even the headline isn't saying that but the headline is sensationalism anyways. As a previous commenter stated (and the OP), since the light as it travels periodically (potentially/probably might be better word choices here) changes into an electron-positron pair, those brief times as massed particles are affected by gravity (naturally) and it adds up to quite an impact at large distances.

Re:subject

[EvilSS]

Maybe I'll feel dumb tomorrow, but I'm pretty sure physics blogs would be exploring right now if this were even remotely true.

also, this is just a blog post...

You've underestimated the speed of news on SlashDOT. It's much slower than the rest of the universe. Those events you mention should have already happened and you should feel stupid yesterday!

Light odyssey

[Anonymous Coward]

The article reveals: Light is just like all those other particles, including those "higher beings" like humans.
Odysseus whored his way through Aegaeis (only say kirke), being incredibly slow at returning home, his original destination. What do we learn today?

As a photon travels through space, there is a finite chance that it will form an electron-positron pair. [...] The new idea is that the gravitational potential of the Milky Way must influence the electron-positron pair because they have mass. [...] light will travel more slowly than [Neutrinos] through a gravitational potential.

You should only send neutrinos onto a voyage this long, seems you cannot trust light. It randomly does funny stuff and gets distracted by huge party clubs like our milky way.

This leads us to only one conclusion: Light is made by the devil to lead us into temptation. Think of Ilias!

Neutrinos, on the other side, are made by god.

Re:Light odyssey

[muridae]

Neutrinos have virtual particle interactions as well. Only low energy photons seem not to (that I remember diagrams for, maybe they do too).
So ALL THINGS are made by the devil except for infrared light and AM radio. Seems to explain why looking at things makes you question stuff (visible light is a lie!) and only AM radio tells the truth.

'less nerdy version' for five-year-olds.

[new death barbie]

Photons travel slower than neutrinos because they dawdle.

That's not what I took away from this...

[SXO148]

From what I gathered, the basis of Franson's hypothesis is the idea that a photon can spontaneously split into a matter-antimatter pair (this is also the idea behind Hawking radiation). Unless something crazy happens (again, see: Hawking radiation), that pair will almost instantly recombine, creating a photon with the same size and energy as the original photon.

Franson's idea, as I understand it, is that during the small window between creation and annihilation, the massive particles are under the influence of gravity, which bleeds off energy. When the pair recombines, it results in a reduced velocity of the photon.

Now, as I understand it, reducing the energy of a photon would merely reduce its frequency (red-shifting), not affect its actual velocity.

However, over long distances, the total time required for a photon to travel distance X would thus be slightly more than X/c, based on the proportion of time spent as a pair of massive particles, rather than as a massless photon. From a statistical perspective, this yields an average velocity of slightly less than /c/ (the speed of light in a vaccuum).

This seems reasonable to me, at least at first.

mrsquid0 raises an issue, though: Photons in the visible light range are not sufficiently energetic to create an electron-positron pair. I do not know if the photons in question were in the visible light range or not.

NoNonAlphaCharsHere also raises an important point: the electron-positron pair *cannot* travel at the speed of light. In fact, he/she raises an even better idea than Franson; my reading of Franson's explanation is that gravity is slowing down the particles (gravity field behind the photon), but there's just as much opportunity for gravity to *speed up* the particles (gravity field in front of the photon).

Now, I don't feel like doing all the math for this one little message, so here are the things I would consider before taking this article (and the original paper) at face value:

• This is predicated upon the idea that gravitational fields affect neutrinos less than they do photons and ordinary matter. Do we know this to be true?
• For the slowing down of the e-p pairs bit, there are two opposing forces:
  • I expect that higher-energy (higher-frequency) photons are more likely to generate an e-p pair than lower-energy photons. This means they are more likely to be slowed down
  • When a photon of energy /E/ forms an e-p pair with combined mass /m/, there is E - m*c*c energy unaccounted for. I expect that that energy ends up as kinetic energy, resulting in a velocity v = sqrt(2 (E - m*c*c) / m). Therefore, higher energy photons will have more energy left over and the e-p pair will thus being going faster.
• According to the Wikipedia article on Pair production, the spontaneous formation of a matter-antimatter pair can only occur inside a nucleus (or momentum could not be conserved). However, this necessarily involves the photon traveling through a non-vacuum, which will necessarily slow it down.

Re:That's not what I took away from this...

[radtea]

Photons in the visible light range are not sufficiently energetic to create an electron-positron pair. I do not know if the photons in question were in the visible light range or not.

The photons were in the visible, but the e+/e- pair exists "off the mass shell", which is an obscure way of saying that the normal conservation laws don't apply. There is an uncertainty relation that goes dE*dt >~ h/2Pi, which is to say: you can violate the law of conservation of energy by any amount so long as you do it for a short enough time. That's what's happening here.

That said, this whole thing is pure speculation, and somewhat problematic speculation at that. If you take the first neutrino detection seriously, the real question becomes not the difference between the first neutrinos and the light, but why the one neutrino detector has such a different arrival time. Conventional wisdom is that it is an instrumental artifact, and that's a pretty good bet.

If it is not--and this slowing-down-light is real--then we need even more new physics to explain why the Mont Blanc neutrino detector saw such different arrival time from three other detectors: Kamiokande II, Baskan and IMB, all of which detected events that are consistent in time of arrival.

Their energy sensitivities are not that different, and there's no very obvious explanation of why some neutrinos would happen to make it out earlier than others, particularly when segregated by detection technology.

Re:That's not what I took away from this...

[muridae]

Franson's idea, as I understand it, is that during the small window between creation and annihilation, the massive particles are under the influence of gravity, which bleeds off energy. When the pair recombines, it results in a reduced velocity of the photon.

I read it as just barely changing the vector of the light, not the velocity. All photons travel at c, but gravity could make the path of travel curve more than previously thought.

Re:That's not what I took away from this...

[Anonymous Coward]

I read it as - while it is not light, it is not travelling at the speed of light - and it spends some time as not light.

Re:That's not what I took away from this...

[Anonymous Coward]

NoNonAlphaCharsHere also raises an important point: the electron-positron pair *cannot* travel at the speed of light. In fact, he/she raises an even better idea than Franson; my reading of Franson's explanation is that gravity is slowing down the particles (gravity field behind the photon), but there's just as much opportunity for gravity to *speed up* the particles (gravity field in front of the photon).

So how does that affect the measurement of objects observed via gravitational lensing? In an Einstein Ring (that is not overly strangely shaped on the other axes), I would think the red-shifting and blue-shifting caused by this effect would just about even out. There could be some situations where the angle/asymmetry to a lensing effect would cause more time to be spent in one vs. the other, affecting the measurements.

Also, does this throw off the calculations for the CMBR? Because when it was released it was mostly visible and ultraviolet. I was unsuccessful when googling to find out how dense it was. It would be interesting to know strong the gravitational gradients were back then, to know how much that would have affected the light when the plasma finally cooled enough for the CMBR to be released.

Re:That's not what I took away from this...

[Anonymous Coward]

However, over long distances, the total time required for a photon to travel distance X would thus be slightly more than X/c, based on the proportion of time spent as a pair of massive particles, rather than as a massless photon. From a statistical perspective, this yields an average velocity of slightly less than /c/ (the speed of light in a vaccuum).

It isn't correct to think of it statistically spending some time as a photon and some time as a pair. Propagation of a photon (and other particles) under quantum field theory gives that the path taken is an average of all possible paths weighted by their probability, some of these paths involve momentary pair production and other times they don't. The speed of light c already takes this into account, as things like speed and masses of particles are things that we can actually measure, and QFT is consistent by saying the speed things travel between virtual pair production or without virtual production at all is unmeasurable (and to some degree irrelevant, as only the final accumulation of all those effects is what we see in the universe). However, if something messes with those virtual pairs, that can impact the total speed. But just the fact that there are virtual pairs in the process doesn't give you a velocity below c.

Photons in the visible light range are not sufficiently energetic to create an electron-positron pair. I do not know if the photons in question were in the visible light range or not.

Photons of any energy can create virtual pairs, as the process doesn't directly respect energy conservation, but only high energy photons or photons in a high energy process with enough energy can create a real pair that can separate.

NoNonAlphaCharsHere also raises an important point: the electron-positron pair *cannot* travel at the speed of light.

As was attempted to explain above, this is irrelevant and doesn't change the speed of c.

my reading of Franson's explanation is that gravity is...

This is the important part that results in a change in speed of light through space, the introduction of an outside force on the process.

I expect that higher-energy (higher-frequency) photons are more likely to generate an e-p pair than lower-energy photons. This means they are more likely to be slowed down

The process given in the paper is independent of wavelength of the photon. At the very end the difference in photon energy for different wavelengths cancels out, and you get an effect that only depends on the fine structure constant and gravitational potential.

When a photon of energy /E/ forms an e-p pair with combined mass /m/, there is E - m*c*c energy unaccounted for. I expect that that energy ends up as kinetic energy, resulting in a velocity v = sqrt(2 (E - m*c*c) / m).

Virtual pair production doesn't respect energy conservation in that way. The process of averaging over all possible paths of the photon also averages over all possible energy/velocities such pairs can come out at.

According to the Wikipedia article on Pair production, the spontaneous formation of a matter-antimatter pair can only occur inside a nucleus (or momentum could not be conserved). However, this necessarily involves the photon traveling through a non-vacuum, which will necessarily slow it down.

This is only for production of real pairs, and can happen outside of a nucleus (but is much less likely to do so, so effectively happens with the nucleus when dealing with gamma rays hitting typical atoms). It still requires an outside particle, or even an outside force (effectively mediated by a particle anyway...), such that you can get pair production from a gamma ray entering an intense macroscopic field like around a pulsar.

Re:That's not what I took away from this...

[Anonymous Coward]

Surely the location of the gravitational influence wouldn't matter? After all, the briefly-existing particle-antiparticle pair would be pretty massy (compared to neutrinos) and would move a lot slower than c, irrespective of the presence or direction of a gravitational influence. Which makes me wonder what gravity has to do with it.

Re:That's not what I took away from this...

[Bryan Ischo]

If it's path curved, even infinitesimally, then it would miss us, wouldn't it? Unless you're saying that it curves one direction and then back again in a crazy squiggle pattern, somehow always re-aiming directly at us. Which doesn't sound remotely plausable.

Re:That's not what I took away from this...

[Anonymous Coward]

The star sent photons in all directions (a sphere). Another photon that would have missed us hit us because of the curved path.

Re:That's not what I took away from this...

[Anonymous Coward]

Since light produced by the supernova is emitted in all directions, and if light is deflected on the way, then some light that would have missed us had it not been deflected would then hit us.

Re:That's not what I took away from this...

[Neil Boekend]

Nope. The photons are emitted in all directions. The photons that hit us are just not the photons that happened to be emitted straight at us (originally) . They are the photons that happened to hit us after they went through all these gravitational lenses after they were emitted.
They are from another part of the surface of the supernova and were originally emitted in another direction.
But all these effects are minute. If they do not pass close to a great mass the angle difference is not measurable with modern telescopes. However, the detours mean that their path is 4 light hours longer over a total trip length of 168000 light years. Which is only a minute part of the trip.
We can only measure it because the neutrinos arrived before that (no detours).

Re:That's not what I took away from this...

[Anonymous Coward]

Since the electron-positron pair has mass, and are travelling very near the speed of light, doesn't that mean that at any given time some proportion of all photons is in this state and therefore has mass? Moreover, if I am remembering correctly, doesn't mass effectively increase when approaching the speed of light, and therefore, while these objects are generally not very massive in our day-to-day, they are at these velocities? Could this in turn be part of the explanation for the "missing" mass in the universe?

Re:That's not what I took away from this...

[Anonymous Coward]

They did miss us. But others, that didn't set out in our direction initially (as the neutrino flies) were affected as well and some of those did hit us.

Re:That's not what I took away from this...

[jwdb]

To quote the article...

Many astrophysicists believe that supernovas can also undergo a second collapse, generating an additional burst of neutrinos. Thatâ(TM)s why the detectors on Earth spotted two bursts.

Or is this a minority theory? I'm no astrophysicist, so couldn't tell you myself.

Re:That's not what I took away from this...

[Anonymous Coward]

mrsquid0 raises an issue, though: Photons in the visible light range are not sufficiently energetic to create an electron-positron pair. I do not know if the photons in question were in the visible light range or not.

That's no problem, after all, virtual particles are created and destroyed all the time in a vacuum, without any photons around. The presence of the photon should just mean that less energy needs to be borrowed...

I'd think the question here should be, how the photon is "re-created" after the e-p pair anihilates, i.e. what mechanism ensures that direction and frequency remain unchanged.

Re:That's not what I took away from this...

[Anonymous Coward]

I'd think the question here should be, how the photon is "re-created" after the e-p pair anihilates, i.e. what mechanism ensures that direction and frequency remain unchanged.

Conservation of energy and momentum. The process of determining the propagation of particles only takes into account paths and processes that conserve energy and momentum. Why that? That kind of gets you at the "that is the way things are based on what we see" point.

This seems a little 'cranky'

[Anonymous Coward]

Note that this paper has been around for 3 years (which the linked article acknowledges). But it started out as a paper about the superluminal OPERA neutrinos -- which turned out to be wrong (a loose cable). The fact it's been on hep-ph (the high-energy physics preprint server) for 2.5 years in various forms without being published should raise alarms. Not conclusively... but at first sniff this smells very much like semi-crank science by press release. Nothing about the listing suggests it's even submitted anywhere.

Re:This seems a little 'cranky'

[Anonymous Coward]

Sorry, correction: it's been published, and in a refereed open-access journal. Still...

Re:This seems a little 'cranky'

[Anonymous Coward]

The paper itself acknowledges that there are some big problems with the result, particularly that it is unphysical for something to depend explicitly on the value of gravitational potential. The author seem to think more careful calculations will address this, but points out it seems fortuitous to get a match to observations with this quicker attempt.

Einstein?

[Anonymous Coward]

The source posits that one scientist claims the speed of light must be slower than Einstein predicted.
The scientist is an idiot. Einstein never predicted the speed of light, nor made any contribution to the measurement of the speed of light. He used c, long established, as a constant in his relativity thought experiments.

"more or less exactly"

[glwtta]

That is the stupidest thing I've read today.

The headlines seems needlessly sensationalist (I know, shocking!) since apparently we're saying that photons don't always travel at the speed of light, not that the speed of light needs to be "corrected".

CAR ANALOGY, SUCKAS!

[gman003]

Okay, let's say you have two cars, a Porsche and an NSX (representing a photon and a neutrino, respectively). Both are limited by the same speed limit, which they always travel at (the speed of light).

Well, due to some weird quantum mechanics, every so often that Porsche splits into a pair of motorcycles, because apparently they got bought by Wayne Enterprises or something (in actuality, they split into an electron and anti-electron). They almost immediately join back together (forming a photon again), but while they're motorcycles, they are affected by wind (gravity). They still can't break the speed limit, but sometimes it slows them down just a bit.

When you're traveling almost literally between galaxies, that little bit of slowdown for tiny snippets of time can really make a difference. In this case, the NSX made it here a few hours earlier.

Re:CAR ANALOGY, SUCKAS!

[Voyager529]

In other words, the photon is like embarrassing photos of Kim Kardashian on TMZ, and a neutrino is like relevant news stories on Slashdot? :-P
Thanks for the help =)

wonder if this could relate to observed red shift

[SergeyKurdakov6434]

While it is quite speculative, but what if this effect makes father light sources to be more redshifted? Then observed accelerated expansion of the Universe might be explained by just interaction of photons with some matter while light travels, the more it travels, the more the shift and not because of relative speed of galactics

How can neutrinos move at the speed of light?

[Anonymous Coward]

If they have a nonzero rest mass, they can't. And they do have a nonzero rest mass.

He's not messing with c

[Anonymous Coward]

The speed of light in a vacuum unaffected by other masses is still the same.
It's just that light rarely travels in such a place.

His division of the 7.7 hour observed arrival time difference into two parts seems suspect.
      Figuring out how long it takes for a photon to diffuse out and escape from the supernova seems likely to involve some magic calibration constants.
      Likewise knowing how often the photon switches to mass, pauses, and switches back and continues.

I believe that part of th 7.7 hours is likely due to this mechanism, but am skeptical as to exactly how much.
    If we accept that light travels slower than we thought, and we use it's speed to measure the Universe, then our measurements are off.
    Not off as in could be only 6000 years old, but at least some small fraction needs adjusting.

Neutrinos don't travel at the speed of light

[Anonymous Coward]

They have mass...

Space isn't a perfect vacuum?

[Anonymous Coward]

Maybe I'm just being really simplistic here, but neutrinos don't interact electromagnetically. Photons do. Space is a near vacuum, so the approximation of index of refraction =1 is close, but wouldn't the photons pass through, and near, enough movable charge over those many lightyears that they would pass through areas of slightly higher index of refraction, adding to the time of flight? The neutrinos would have a straight shot through for much the same reasons as they do out of the star: no pesky electromagnetic interactions.

Bad summary/Theory Conflicts with data

[forand]

The summary (and linked article) do a poor job of explaining the process and imply some change in the speed of light (there isn't one). The problem with the article (http://arxiv.org/abs/1111.6986) is that it ignores a bunch of more relevant data: Fermi-LAT observed photons from the same GRB over a very wide energy range placing an extremely good limit on effects like this proposed in the article (http://arxiv.org/abs/1305.3463).

Furthermore this is NOT new; the original article was posted in 2011 and only recently published in the "New Journal of Physics" which has apparently only published 16 volumes and I believe has had its email permanently redirected to my spam box.

Finally why do people link to Medium and not the actual article for physic related news items? We have demanded open, free access to all our papers since the birth of the internet (I speak as a physicist). Do everyone a favor and find the arxiv link and include it in your summary when submitting physics stories to Slashdot.

Re:Bad summary/Theory Conflicts with data

[Anonymous Coward]

16 years is kind of old for a journal created with the intention of being online only and open access. An impact factor, for what that is worth, of 4 something isn't great but isn't nothing either.

Do everyone a favor and find the arxiv link and include it in your summary when submitting physics stories to Slashdot.

Unless they edited the summary within the first hour or so of it being posted, the arxiv link was at the end of the summary.

Re:Bad summary/Theory Conflicts with data

[Anonymous Coward]

NJP is a reputable journal associated with DPG (the main German physical society) and IOP (a large and respected physical society with British origin). Of course the paper could still be wrong.

Lies, all lies

[penguinoid]

Apparently, there's a 1 in 10,000 chance that it's all a coincidence... and if you consider the number of observations being made, and the implications (aka other observations we should see), that's a really high chance. For example, it would mean that the Large Electron–Positron Collider was accelerating particles to faster than the speed of light in a vacuum, without anyone having noticed.

Expansion of universe?

[nalcorso7770]

Could this go on to contribute to the explanation of the increase in expansion of the universe? if the distance between gravitational wells is increasing then the gravitational effect on the electron / positron pair would be reduced prior to them recombining in to a photon?

I am dubious

[mbone]

When 1987A happened, it is fair to say that an enormous amount of attention was placed on those neutrinos - >> 1 paper per neutrino. The report of an earlier neutrino burst from the Mt Blanc LSD was discussed at length - see Arnett 1987 Table 1 for the time line.

The facts are these - the optical supernova could not be accurately timed, it wasn't bright at Feb 23.10 and it was at 2 / 23.443. The Mt Blanc LSD burst was at 2 / 23.12, while the other two detectors had a mutual burst at 2 / 23.316. Note that both neutrino bursts occurred before the optical SN was detected, and also that none of the other detected picked up the Mt Blanc LSD burst.

All of this has been known a long time, and numerous theories have been introduced to explain it.

- formation of a nlack hole (from the neutron star)
- formation of a quark star (from the neutron star)
- the Mt Blanc data were unrelated to the SN (that appears to be Arnett's viewpoint).

So, this is another explanation, and not a super compelling one to me. It will clearly never be proven from the SN 1987A data - the next such close supernova should have a lot of neutrino data, and maybe will resolve the issue.

so how fast

[Anonymous Coward]

does the Enterprise go now?

Big Assumption?

[Anonymous Coward]

Are we assuming that there is a complete vacuum between the source of the photons and the detectors on Earth?

The title is misleading...

[Anonymous Coward]

There is no "correction" to the speed of light. The speed of light is a constant and will always be the same. They are simply stating that in certain circumstances like in a supernova, light can be slowed down a bit from the start. The speed of light still acts as an upper speed limit. However, this discovery could have some serious impacts on our distance calculations on distant galaxies that were based off of supernovae light in the first place.

Re:The title is misleading...

[Anonymous Coward]

If by "serious correction" you mean a couple parts per million, well within most error bars for such measurements...

Is there a 'less nerdy version'?

[Anonymous Coward]

Photons regularly turn into an Electron/Positron pair, which then almost immediately turns back into a Photon. The photon still moves at the speed of light, but for the very short period in which it is an Electron/Positron, it is affected by gravity and slowed down. Over the course of around 160,000 light years (160,000 years of this photon traveling), it was 4 hours behind a neutrino which did not exhibit this behavior.

the force is weak with this one

[dlenmn]

and oh by the way photons can momentarily turn into other shit on their journeys yet somehow neutrinos can't.

I don't study particle physics, but from what I understand, for photons or neutrinos to "turn into other shit", they need to interact with something -- such as the particles they create, atomic nuclei, etc. Photons interact through electromagnetic forces -- which is the strongest force out there. In contrast, neutrinos interact via the weak force. As you might guess, that force is very weak. That's why neutrinos are so hard to detect.

Since photons interact with "other shit" via a much stronger force than neutrinos, photons are much, much, much more likely to "turn into other shit" than neutrinos are.

So, sorry internet troll, this isn't "cherry picking"; it's science. Deal with it.

Re:the force is weak with this one

[Parlyne]

The need to interact with something to "turn into other shit" is a requirement for transitions into other "real" particles. For instance, to actually get out an electron/positron pair from a high energy gamma ray, the gamma needs to interact. But, what we're actually talking about here are what are often term "virtual particles," which are better thought of as excitations in those particles' quantum fields that show up with the wrong mass to be real physical particles. These sorts of excitations happen spontaneously even without interactions, but very quickly transition back to the original state.

Re:the force is weak with this one

[Anonymous Coward]

The previous poster was kind of half right, that while it doesn't need to interact with another outside particle, particles will only form virtual pairs based on the types of interactions they can be involved in. Neutrinos will form different virtual pairs via the weak force than the photon would via electromagnetism.

Re:the force is weak with this one

[JasonGoatcher]

Somebody needs to take a basic physics concept and "translate" it into Valley Girl, dudespeak, etc... I've seen it done with the Lord's prayer and Blood gangmember slang, hmmmmmmm...

To Google I go.

anyone ever considered

[ihtoit]

...that the definition of the speed of light includes the term "in vacuo" for a reason?

It means, literally, "in vacuum". As in, the complete absence of matter along the path. Which is impossible even in laboratory conditions, never mind out in space where deep interstellar density runs on the order of tens of atoms per cubic metre. That might not sound like much but with the quantum probability of a photon polarising and forming a pair with mass, that pair will be subject to gravitational effects (even from a dust particle). The vector is changed for the pair and therefore the photon. There is an increasing probability that on its way through a region with stellar-plus-sized masses, the photon/pair will be subjected to immense gravitational effects resulting in a lensing effect to the observer. This does NOT mean that the speed of the photon is changed - it is still travelling in a pretty constantly rare soup - only that its path is changed. Its lens-pair photons will arrive at the same time to the observer *providing they do not encounter another lens on the way* - which given an infinite universe is a definite possibility, however unlikely/unobserved within our observation sphere. Should this happen, I predict a delay between one photon path intersecting the observer and another from the same source at the same instant having passed through a lens. Could this be predicted using a single light source and two sensors: one through a glass fibre path straight to the source and another through a glass fibre path of the same material characteristics but that takes a longer and more circuitous route?

Re:anyone ever considered

[Anonymous Coward]

Should this happen, I predict a delay between one photon path intersecting the observer and another from the same source at the same instant having passed through a lens.

In some sense this is how all optical lenses work, by inducing different delays for different paths. Fermat's principle and modern versions of it amount to light basically taking the shortest path and hence changing the time it takes for different paths changes the paths light takes. The problem with a simple gravitational lens is its effect would only depend on the velocity of what was passing by, so the neutrinos and photons would follow the same path (the difference in speed between a neutrino and c is much, much smaller than the effects being discussed in this article). And that doesn't explain a time difference between the two things coming from the same place. Also, since the supernova being discussed was barely outside our galaxy, it is easy enough to see if any large stars are directly between here and there.

Let there be light.

[Anonymous Coward]

This is where they tell us traveling between galaxy slows the light and causes it to appear red shifted and that the universe is not really expanding at the rate they think it is and may not be at all in some places.

Better Red Shift Explanation?

[barfy]

Does the extreme distances of very far galaxies red shift and rapid expansion, better explained by vacuum polarization and a slow down of light over extreme distances? So that what we are not seeing is some sort of doppler shift, but instead of something akin to friction over very long distances using this process that both delays the light, and shifts the frequency to red? And if so, does this change the expansion of the universe answer?

Re:Better Red Shift Explanation?

[Anonymous Coward]

This process as described has no wavelength dependence and cannot explain a redshift.

Black holes showed from day one that

[Anonymous Coward]

c is dependent on g, meanwhile x-rays didn't care as much for g. Quantum simply said 'where?'.

Conspiracy theory again?

[jandersen]

... that astrophysicists have brushed under the carpet

To me, this article reeks of conspiracy theory; a valid, scientific critique or proposal has no need for using this kind of language.

Another thing is that the speed of light and its constancy in all inertial frames of reference is a fundamental tenet in all modern physics. It underpins the whole of relativity theory and it is crucial in the explanation of the equivalence between mass and energy; it even explains the colour of gold. In short: one has to be careful fiddling with it, because one will then have to find alternative explanations for A LOT OF OBSERVABLE FACTS.

Re:Conspiracy theory again?

[Anonymous Coward]

To me, this article reeks of conspiracy theory; a valid, scientific critique or proposal has no need for using this kind of language.

That wording only appears in some random blog post on the story, and not in the actual paper at all. The paper only mentions that there is a lack of explanation for the disagreement over the light delay and that the best offered so far is that the first neutrino burst was a coincidence despite the low chances of that, with citations.

In short: one has to be careful fiddling with it, because one will then have to find alternative explanations for A LOT OF OBSERVABLE FACTS.

Corrections in the parts per million would not change the vast majority of effects and observations related to speed of light. Additionally, an effect that depends on traveling from a long ways away, not causing any changes near the surface the Earth, and only parts per trillion for speeds between Earth and near-Earth would be way under the error bars for most observations.

it is crucial in the explanation of the equivalence between mass and energy; it even explains the colour of gold

You could change the speed of light by percent and still get the yellow coloration of gold.

Dark matter?

[zmooc]

So photon's act like matter at bit more often than we expected, right? How much of dark matter/dark energy problem can this phenomenon account for?

My weird-o-meter needs recalibrating...

[Richard Kirk]

This is a story about the speed of light being not what we thought it was, and involving general relativity, neutrinos, and its one data point from a unique astronomical event. Oh, yeaah, riiight. And yet, it is clearly explained, and stands a good chance of being right. I am definitely going to have my weird-o-meter recalibrated.

The speed of light is the same as it always was. Any given photon may, extremely rarely, split into an electron-positron pair, and then recombine. The electron and the positron are not travelling at the speed of light, so this event will stick in a small delay. If you measure the speed of light over most human experimental lengths, this event will be very rare - so the very occasional photon will show a tiny delay. If your light travels over such vast distances that the photon may have experienced so many of these delays that it spent whole hours as electrons and positrons.

Each photon will have a random number of these delay events, so you might expect the light pulse to get blurred out a bit by this randomness. There will be a slight blurring, but because the number of events is so huge, the fractional deviation from the mean is pretty tiny.

Cute, and neat. Some posters still try and argue for gravitational viscosity, or for faster-than-light neutrinos, or that this is a failure of science and only philosophers can help us now. Ho-hum. Too little fog, too late, chaps. Better luck with the next one, eh?

Re:My weird-o-meter needs recalibrating...

[Anonymous Coward]

Each photon will have a random number of these delay events, so you might expect the light pulse to get blurred out a bit by this randomness. There will be a slight blurring, but because the number of events is so huge, the fractional deviation from the mean is pretty tiny.

The process relevant here is the creation of virtual pairs which can affect the propagation of all light equally. The propagation of particles under quantum field theory takes into account all possible paths including ones where there is a virtual pair production. The result is not a blurring, but a change for all particles by the same amount. There are other statistical scattering events that can happen when exchanging energy and momentum with some other real particle, but that is much less common and typically has a strong wavelength dependence (e.g. photons splitting into pairs that then allow a magnetic field to scatter the photon is only relevant to high energy gamma rays near a pulsar with a really strong magnetic field).

The Real Issue

[PortHaven]

Is that we have to redefine the definition of a vacuum. Clearly, most thing of a vacuum as an area containing no mass. However, we should implement a more exact definition of a vacuum as an area not influenced by mass. (gravity, being the long range influence of mass)

Remove the influence of mass (including gravity), and C remains constant. I wager physicists will much more readily accept redefining vacuum than C.

Franson's theory disagrees with solar system tests

[mbone]

Franson's theory cannot be right, as it disagrees with the solar system tests of General Relativity

His Equation 18 predicts a change in the gravitational red shift by a factor of 9 alpha / 64 for photons, where alpha is the fine structure constant (~ 1/137), so the correction is ~ 1.08 x 10^-2. The gravitational red shift has been tested, by GPS and also by Gravity Probe A, with an accuracy of a few parts in 10^-4 (see Figure 3 in that reference). This excludes the Franson correction, and so his theory cannot be correct. Since the Shapiro delay also depends on the gravitational redshift, Franson's theory thus predicts a 1% change in that too, which is also much too large to be consistent with experiment (see Figure 5), again excluding the Franson theory.

So the theory is wrong, and the other problems I have with the paper are irrelevant.

Particles with mass

[cyborg666]

If the photon turns into a pair of massy particles, shouldn't that fact alone slow it down? Anything with a mass can't move at the speed of light. Also, doesn't gravity affect light in a similar way as it affects particles with mass?

Re:Particles with mass

[Anonymous Coward]

Since photons are always doing that and we never see light when they are not including the possibility of splitting, and the speed of light as we know it already takes that into account the virtual pair production. And the idea in the paper here is that since virtual pairs don't respect things like conservation of energy or mass for a brief moment, they interact with gravity differently than the original photon would have.

Re:Franson's theory disagrees with solar system te

[Anonymous Coward]

His Equation 18 predicts a change in the gravitational red shift by a factor of 9 alpha / 64 for photons, where alpha is the fine structure constant (~ 1/137), so the correction is ~ 1.08 x 10^-2.

His equation 18 only gives a change in speed while equation gives the result for a perturbation to the energy. Nonetheless, both equations include a term for the gravitational potential energy, which makes your estimate of the correction way off. In the case of something near the earth, this makes the red-shift a factor of 10^10 smaller than just 9 alpha / 64, which is way below the error bars on such tests. Tests involving other bodies within the solar system still amount to parts per billion changes.

The big issue is that the result explicitly depends on gravitational potential energy (and not a change in potential energy), which makes it unphysical as directly stated by the author.

Howsabout corrective lenses for photons

[doccus]

Looks like it's time for corrective lenses for photons so's they don't keep bumping into stuff...

A *single* photon?

[volpe]

Can a single photon turn into an electron/positron pair? I didn't think this was possible because a photon has no rest frame, whereas an e-/p+ pair always would. Thus, in the inertial frame in which the pair has no momentum (the "center of momentum" frame), the photon would still have momentum. Thus, momentum would not be conserved. You need two photons moving in different directions for the pair of photons to have a center-of-momentum frame in which their momenta cancel each other out.

Re:A *single* photon?

[Anonymous Coward]

Virtual particles don't respect the conservation of energy and momentum. But those conservation laws are part of what prevents them from turning into a real particle, so you won't get a photon turning into a pair on its own and that pair splitting off without some outside interaction.

Multi-Dimensional Time

[TechnoJoe]

No, this is explained by multi-dimensional time. The speed of light is constant. See: The Dark Side of Time

and thus scrodrs cat is solved, some times it is

[Anonymous Coward]

still on it's way... lol. But seriously it is amazing that after the law of conservative it took a dying star a bunch of years, and a lot of really expensive equipment to prove what can be proved my sending an email to two different people. If energy travels at the speed of light and electricity moves at different speeds as light and electricity along wires, of course it has mass. Any network tech could tell you that but what they could not do is prove why.

There is only one mass: it's invariant

[Roger W Moore]

You are mixing up rest mass (which neither the photon nor the neutrino has) with moving mass / impulse

No, actually I'm not: trust me I'm a particle physicist! There are two misconceptions there. First a particle does not have to have a mass to have a momentum. Einstein's favourite equation is not actually 'E=mc^2' unless you are standing still. It is more correctly written: 'E^2=p^2c^2 + m^2c^4' where 'p' is momentum. In the case of a massless particle (m=0) this is just: 'E=pc' so a photon with a non-zero energy has a non-zero momentum but ALWAYS has a zero mass.

The second misconception is that the mass of a moving particle somehow changes. This is wrong and in fact you can show quite easily (if you know relativity) that the mass is something called a Lorentz invariant which means it is the same for all observers in all inertial reference frames. The misconception regarding the mass "getting bigger" at higher velocities comes from the formula for relativistic momentum for a massive particle "p=gamma*m*v" where 'gamma' is always greater than 1 for v>0. This factor is erroneously coupled with the mass to give what some textbooks call 'relativistic mass' (gamma*m). This is WRONG! One of the consequences of relativity is that space and time get 'mixed' differently for different observers. Velocity is 'space/time' so this is where the gamma factor comes from. This is very obvious to see if you look at acceleration. The relativistic form of Newton's second law is NOT 'F=gamma*m*a' which it would be if this was just an effect on the mass increasing.

You claim that a neutrino has always mass (or more than a photon) is either plain wrong or grants you a noble prize if you can proof it.

See this paper: “Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory”, The SNO Collaboration, Phys. Rev. Lett. 89, 1, 011301 (2002). It is not possible for neutrinos to oscillate unless they have a mass difference which means that at least two of the neutrino flavours must have a non-zero mass. You are correct that it is likely to win the authors a Nobel Prize probably within the next few years but I'm not one of them (but I was an author on the Higgs discovery paper so that's ok! ;-).

Re:There is only one mass: it's invariant

[Anonymous Coward]

You're either over simplifying the arguments about the concept of relativistic mass, or have taken a particular side on the argument and acting like the other doesn't exist. That is not a case of physicists versus inexperienced non-physicists, but an on going argument among physicists, and something that is still covered, depending on the professors, through graduate level (I was there...). However you label it, the arguments of neither side changes the physics, it just comes down to labels and how you group things, and mostly arguments come down to how it impacts students trying to learn the subject. And while the naive form of Newton's second law F=gamma*m*a does not work, the other form, F=d/dt (gamma * m * v) does work, and in that sense relativistic mass does still work like mass. At least there is universal dislike of longitudinal and tangential mass these days.

Re:There is only one mass: it's invariant

[angel'o'sphere]

So you want to tell me that a moving photon still has no mass? And no impulse? Well, impuls is defined as h / lambda. From that follows it has mass. And that mass is what is behind the idea of solar sails, e.g. or the momentum. Anyway, I was so far of the opinion you would only say: the photon has no rest mass, but has an relativistic mass. I would bet that is what is written in my old physics book. But perhaps that is a simplification for low level physics teaching? That is annoying :) as this fact never got corrected in my physics studying at the university (I only did the very basics, just a little bit beyond school physics)

Hm, I will read up about what you mention about the oscillating neutrinos, I was not aware that this implies they have a mass. How is 'that mass' different from the relativistic mass of a photon? (In case that is explainable in a few simple sentences ;) )

Ah, well if you are such a hard core physicist, then I wish you luck, perhaps you are once in a team with a chance to get a noble price!

Relativistic Mass is fundamentally wrong

[Roger W Moore]

"moving mass" here is being used for poorly named relativistic mass, which is not an invariant. For both gravitational and inertial purposes, things act like their relativistic mass in a given frame, regardless of what their rest mass is.

Actually they do not. Try using 'F=ma' with relativistic mass and you will not get far. You can only use the simple 'gamma' factor when dealing with relativistic momentum and then, at a fundamental level, it comes from the fact that the particle's velocity has to be redefined for relativity because there is no universal clock. This is not a pedagogical argument it is a fundamental physics argument: relativistic mass is a broken concept, the universe simply does not work that way and you will go wrong if you use it in any but the simplest situations.

Re:Relativistic Mass is fundamentally wrong

[Anonymous Coward]

Try using 'F=ma' with relativistic mass and you will not get far.

Try using F=d/dt mv ...

This is not a pedagogical argument it is a fundamental physics argument: relativistic mass is a broken concept, the universe simply does not work that way and you will go wrong if you use it in any but the simplest situations.

No, you're just illustrating why it is a pedagogical issue, because it works if used correctly, but comes with some caveats and requires understanding of the principles in the right mind set. F=ma doesn't work naively in any case where the mass is not constant, relativistic or not.

Re:Relativistic Mass is fundamentally wrong

[Roger W Moore]

Try using F=d/dt mv ...

Yes...and that does not work at all for relativity since you are missing the gamma factor.

F=ma doesn't work naively in any case where the mass is not constant, relativistic or not.

True but it doesn't work even when mass is constant e.g. for an instant of time under relativity because the 'gamma' factor is a correction to the velocity, and here you have acceleration so there is no simple gamma factor. You are also wrong that it is purely pedagogical because at a fundamental level we know that e.g. the mass of an electron is due to its coupling to the Higgs field. This coupling does not become larger with an increase in energy hence the electron mass remains constant. Still not convinced? Einstein himself argued against the concept.

Re:Relativistic Mass is fundamentally wrong

[Anonymous Coward]

Yes...and that does not work at all for relativity since you are missing the gamma factor.

m=gamma*m_0 using the same notation as used by Einstein before he changed his mind about the notation. Many others following him his change continue to use that. Either you're being disingenuously dense by not recognizing that, or you've led a really sheltered life as a physicist (and are still being kind of dense considering the line was "using relativistic mass"...). Knowing this notation and concept exists and that it is functional is not the same saying it is best practices. Even professors that don't like using that concept warn their grad students about it because it comes up in papers still, or if going through older papers. MTW at least briefly brings it up to justify why their approach is easier instead of using the "3+1" system. Most QFT and some GR books avoid the issue by just using natural units, in which case total energy and total mass would be indistinguishable (even with c!=1, they are the same, just different units...). Other text books ranging from Coh-Tannoudjio to multiple modern physics and university level intro physics textbooks still stick with the relativistic mass system when glossing over stuff.

e.g. the mass of an electron is due to its coupling to the Higgs field.,

And the Lagrangian for that is Lorentz invariant, but that doesn't mean energy is invariant under Lorentz transformations...

Re:Relativistic Mass is fundamentally wrong

[Roger W Moore]

Even professors that don't like using that concept warn their grad students about it because it comes up in papers still

Not in particle physics - I've never seen that notation used: 'm' always means the invariant mass. Perhaps if you go back to the 1950's but then you are really using textbooks and not papers and again they use invariant mass. If you write momentum as 'mv' I bet you would not find a single physicist in any reputable particle physics group that would think you meant it as a relativistic expression.

Other text books ranging from Coh-Tannoudjio to multiple modern physics and university level intro physics textbooks still stick with the relativistic mass system when glossing over stuff.

Rubbish. The intro texts typically introduce relativistic mass and then describe it as an incorrect and flawed concept (often citing Einstein) and then never, or rarely, mention it again. Senior undergrad particle texts never even mention the concept nor do the grad level texts or modern papers.

And the Lagrangian for that is Lorentz invariant, but that doesn't mean energy is invariant under Lorentz transformations...

Correct but a particle's mass comes from the energy it has in its rest frame which IS an invariant quantity and which is determined by the Higgs coupling for fundamental particles.

Search beyond - Solutions may follow

[Anonymous Coward]

Sub;Search beyond - Solutions may follow
Have we established and understood the significant aspects through Plasma Regulated Electro-magnetic Phenomena under Magnetic field Environment
prevailing at the Galactic Plane that links to Supernovas- like 1987 A.Core flows have different route and Filed aligned flows circumvent in different modes of Nature. The Science of Cosmology and Vedas -Interlinks some of these aspects that include search beyond speed of Light-and Dark mode concepts.
Necessity-promote Cosmology studies East West Interaction in Earnest Spirit-Vidyardhi Nanduri

The speed of light is slow...

[sgroyle]

Dark is much faster.