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Intergalactic Race Shows That Einstein Still Rules
Ponca City, We love you writes "The NY Times reports that after a journey of 7.3 billion light-years, a race between gamma rays ranging from 31 billion electron volts to 10,000 electron volts, a factor of more than a million, in a burst from an exploding star, have arrived within nine-tenths of a second of each other. A detector on NASA’s Fermi Gamma-Ray Space Telescope confirmed Einstein’s proclamation in his 1905 theory of relativity that the speed of light is constant and independent of its color, energy, direction or how you yourself are moving. Some theorists had suggested that space on very small scales has a granular structure that would speed some light waves faster than others — in short, that relativity could break down on the smallest scales. Until now such quantum gravity theories have been untestable because ordinarily you would have to see details as small as the so-called Planck length, which is vastly smaller than an atom — to test these theories in order to discern the bumpiness of space."
they arrived within 9/10th of a second of each other
which indicates the opposite of the story's summary
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
that the photons all left at the same time?
Did anyone else read this headline about an intergalactic people verifying Einstein's theories?
That would be big news, if some smart people had put forward the idea that water, at the molecular level, isn't wet.
(Which it isn't, by the way.)
that these rays are all from a star which exploded 7.3 billion light years away? what was monitored to predict arrival?
So an article about the four color theorem being proved is irrelevant because we were already 99.999% certain before it happened?
What a time we live in where a "slow new day" consists of a 7.8 million year race being recorded (regardless of the results), a fusion reactor is being developed, and a real time speech translator was released.
Some people just like to get offended. It validates their existence.
Who said they didn't? The point is that even if they left at the same instant from the same point .9 seconds is much smaller than predicted by the theory in question.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
I'm curious, why is the Plank-length "So-called"? Hasn't it been firmly established as a unit of measurement?
If our elected representatives no longer represent us, do we still live in a Democracy?
This was proposed by G. Amelino-Camelia et al. back in 1998; here is a review from 2004. Even though the wavelengths of even the most energetic gamma rays are much, much, longer than the Planck length, roughness in space time at the Planck length adds up over cosmological distances, and could be in principle detectable. (The Planck length can be thought of heuristically as the length at which the gravitational effects of virtual particles should be strong enough to create virtual black holes; general relativity cannot be ignored in quantum mechanics at that scale, and vice versa.) What this current test is ruling out is a particular violation of Lorentz invariance - a variation of photon speed with energy. There were similarly negative results using radiation from the Crab nebula in 2003.
It should be noted that this does not rule out quantum gravity - it seems pretty clear that General Relativity and Quantum Mechanics cannot both apply at the Planck scale. What this work is doing is beginning to constrain models of quantum gravity (there is as yet no general theory that makes precise predictions). What would be really cool is to detect some effects, which would maybe help nudge the theorists along.
Most people think J.C. Maxwell helped Ringo with percussion on "Abbey Road". Einstein has Box Office Mojo.
The cost of that cleanup, of course, will be borne by taxpayers, not industry.
So the $500 high-energy gamma-output cables I bought actually DON'T improve my ping?
FUCK YOU MONSTER CABLE!
Aaarrggghh!!!
Genesis 1:32 And God typed
No, TFA seems to say that it's slightly smaller than the theory would predict with the 0.9s difference.
But what if the photons that arrived first had left last? That might put the difference in travel time as high as 3.1s....
"I do not agree with what you say, but I will defend to the death your right to say it"
I'm seriously blown away by how great of a scientist this guy was. I mean, its 100 years later and he is STILL being proved correct. Imagine what we could do if we still had this guy around. Its just so amazing to me.
For the pedantics among you (myself included), please replace "15.6" with "14.6" and "3.9" with "3.65". Somehow I got "7.8 billion" stuck in my head instead of the stated "7.3 billion". Stupid brain!
"This post contains words, known to the State of California to cause thought. Wash brain thoroughly after reading."
This Einstein guy is starting to really piss me off. Someone gotta take him down a notch or two.
Fuck systemd. Fuck Redhat. Fuck Soylent, too. Wait, scratch the last one.
Particle man, Particle man,
Doin' the things a particle can.
What it's like, it's not important, Particle man.
Is he a dot, or is he a speck?
When he's underwater, does he get wet?
Or does the water get him instead?
Nobody knows. Particle man.
If telephones are outlawed, then only outlaws will have telephones.
Worse yet, they changed the outcome of the race by measuring it.
i lost 300 big boys on that!
Utilizing the synergization of benchmark e-solutions to pre-workaround action items!
Of course, most of what he knows isn't true...
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
OK, here's one for the physicists in the audience (and pardon the simplification of terms here, but...)
1) Being deeper in a gravity well slows time relative to being further out.
2) All things which have mass have gravity wells.
3) Photons have mass (NOTE TO THE CLUELESS: "mass" and "rest mass" are two different things - photons have no rest mass, but they most certainly have relativistic mass).
4) By 2 and 3 photons should have a (small) gravity well. More massive photons (higher energy and thus shorter wavelength) have deeper wells.
Thus, wouldn't 1 and 4 lead to higher energy photons "clocks running slower" (since they are deeper in a gravity well) and thus propagating as a lower speed as viewed by an observer outside their gravity well - and that effect would be negligible for all but the most massive photons.
(for the physicists: feel free to expand and clarify on the oversimplifications I've made here. This is, after all, targeting a Slashdot audience which has rather a wide spread of backgrounds).
www.eFax.com are spammers
Better analogy (RTFA)
A - My brother and my parents left the same destination within 2 seconds of each other
B - They traveled along the same path without stopping to my house in different vehicles
C - They arrived at the same time
D - therefore they traveled at the same speed
Are they driving the same route? Did your brother not ride with so he could burn down a j? Will he share?!?
This is actually just the latest in a series of measurements of this type. Since the Nature paper isn't free online, people may want to look at this similar paper from earlier this year that is available.
The article talks about testing "some theories" of quantum gravity. AFAIK the only theory of quantum gravity that makes anything like a prediction that could be tested in this way is loop quantum gravity (LQG). The two leading contenders for a theory of quantum gravity are LQG and string theory. String theory essentially assumes a background of flat spacetime (plus an xtra 6 rolled-up dimensions), so I don't think it's capable of addressing the issue of whether spacetime is frothy at the Planck scale. LQG doesn't assume a background of flat spacetime, and in fact one of the main research programs in LQG is focused on showing that flat spacetime can emerge as a solution to LQG in the appropriate limit. LQG unambiguously predicts that the vacuum is dispersive, i.e., that the speed of light depends on the energy of the photon. However, LQG does not unambiguously predict the exact form of the energy-dependence. The possible form that is usually assumed in order to evaluate observational tests is |v/c-1|~(E/E_P)^n, where v is the speed of the photon, c is the speed of cause and effect in relativity (often referred to as the speed of light), E is the energy of the photon, E_P is the Planck energy, and n=1 or 2. Previous observations, such as the one in the arxiv paper I linked to above, have pretty much ruled out n=1, so if LQG is right, we'd presumably have to have n=2. Some people have been saying that LQG is ruled out by these measurements, but I don't think that's really correct, it's just constrained by them. Here is a paper by LQG researchers discussing the empirical tests, and they don't seem to be saying "OK, we give up." It's actually very exciting for people in quantum gravity to have observations that even have some chance of disproving a theory (or some version of a theory); the whole field is a dead end if it can never be tested by experiment.
In a broader sense, the holographic principle gives strong, model-independent reasons for believing that spacetime is probably discrete, not continuous, at the Planck scale. Otherwise it's hard to imagine how there could be an upper bound on the information content of a given region of space. And any theory in which spacetime is discrete at the Planck scale will naturally give a dispersive vacuum. Therefore I'd say that either (a) we should eventually observe dispersion of the vacuum once the observations get sensitive enough, or (b) the holographic principle is telling us something that we don't yet understand.
Two good popular-level books that get into this kind of thing are Three Roads to Quantum Gravity by Smolen, and The Black Hole War by Susskind. Because Smolen and Susskind represent very different points of view on quantum gravity, anything that both books agree on is probably correct.
Find free books.
Didn't they stop at a diner along the way?
But what if the photons that arrived first had left last? That might put the difference in travel time as high as 3.1s....
I think the scientists writing the paper and the reviewers already considered that possibility. The paper sets bounds on how big of an effect energy / speed interactions could be for photons so they probably used worst case situations to establish the upper or lower bounds as needed.
"When you sit with a nice girl for two hours, it seems like two minutes. When you sit on a hot stove for two minutes, it
Yah, but think of the poor string theorists. Here they spend 30 years working on it, and they stack the department hiring processes so they will not be criticized for never have created a testable conjecture. Now some data comes in and half their theories crash.
Your point is well made, but it was 7.8 billion years.
872835240
I think item B in your list is actually the thing that we're trying to test here. So more like:
A - My brother and my parents left the same destination within 2 seconds of each other
B - Because of the difference in suspension between the two vehicles, if there had been any potholes bigger than a certain size, one vehicle would have had to travel slower than the other
C - They arrived within 0.9 seconds of each other
D - Therefore there were no potholes bigger than the size mentioned above
(There might possibly be smaller potholes, too small to affect either of the vehicles in this test. You could repeat the experiment with a bicycle, a skateboard, and one of those roller wheels you use to trace distances on a map.)
Except that youre relying on the fact that they arrived at the same time to infer that they came from the same place, and using that inference to validate their travelspeed. Thats called circular reasoning.
I thought the speed of light does depend on the medium through which light travels.
* http://en.wikipedia.org/wiki/Dispersion_(optics)
* http://en.wikipedia.org/wiki/Prism_(optics)
What they measured is a bit surprising that way.
Stephan
http://stephan.sugarmotor.org
I heard a good analogy once explaining just how small the Planck length really is--and why it's so out of reach of any conceivable measurement we can even dream of:
If the nucleus of a single atom were expanded to the size of the known universe (15 billion light years across--itself an almost unimaginable distance), the Planck length would be about as long as a tall cedar tree.
SJW: Someone who has run out of real oppression, and has to fake it.
It's plausible that these two photons left 0.1 seconds apart, and in their journey the distance between them expanded with the rest of the universe around them until at their arrival they were 0.9 light seconds apart. The event was observed to be 2.2 seconds long from our point of view but in local time at the event it took much less time (0.27 seconds). At least that's my understanding of 8.2 redshift.
Help stamp out iliturcy.
Comment removed based on user account deletion
Actually I could argue that water itself isn't wet - it just makes things wet. This is because the definition of wet is 'to be covered or soaked with a liquid such as water'.
Tesla was a genius. Edison however was a overrated hack who liked to torture puppies.
Man oh man.. I stepped out to use the bathroom and I missed it... I had been waiting 7.3 billion years for this.
One interesting thing that stood out is they used the assumption that the effect of quantum gravity would be proportional to the energy of the light; is this what the theories suggested or is this another case of science getting lost in the translation to newspapers?
As far as I understand from my colleagues who worked on this analysis (now departed for other groups/institutions), the theories of quantum gravity which predict a linear relationship between photon energy and propagation speed are the simplest to test. There are other theories, and they are worth testing too, and some of them would no doubt also be falsified by the Fermi data, but the analysis to do so is more difficult and more complicated, so nobody has done it yet.
SIGSEGV caught, terminating
wait... not that kind of sig.
An extremely careful analysis would probably set much more stringent bounds. We (scientists) don't always have time to be that careful, so we generally go with much coarser estimates of uncertainties and the like, resulting in very conservative bounds.
SIGSEGV caught, terminating
wait... not that kind of sig.
In "The Elegant Universe" Brian Greene http://en.wikipedia.org/wiki/Brian_Greene made a similar analogy in regards to string theory: if an atom were expanded to the size of our solar system, an individual string would be the size of a tree.
However, He didn't specify what kind of tree.
I thought electromagnetic radiation of different frequencies traveled at different speeds through a medium (as opposed to a vacuum). In this case, the medium would be intergalactic gas, very thin, but there's 7 billion light years of it. How come that didn't spread things out? Is it because the frequencies involved are so high?
In theory, theory and practice are the same; in practice they're different. (Yogi Berra & A. Einstein)
Was there ever a doubt that Einstein still rules. Just look at Isaac Newton, that "gravity" of his was made a law. Hooray, Science! *Just stating the obvious* -Stak
Holy happy hippy crap!
The observed time between the events could represent a much wider differential thanm the .9 seconds. If the faster photon starts at the begining of the 'ka', and the slower one starts at the end of the 'boom', with the faster particle passing the slower one sometime during the 7.3 million years, then you have a possible difference of (0.9 + 2.2 + 0.9) = 4 seconds. What is the expected time differential expected if the speed is based on wavelength?
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
For those of us who have a subscription to Nature but not to NYT for whatever reason: Here's the original article.
Yeah, same here. I had mixed feeling about receiving the first news of alien life from frickin' /.
Here's one theory that posits the speed of light would vary depending on the energy scale. Basically the thinking is that the Planck length should also remain an invariant quantity regardless of the reference frame, so you modify the Lorentz transformation in such a way to make that work.
http://en.wikipedia.org/wiki/Doubly-special_relativity
I was going to say that this:
must be how god myths start.
Now he's earning money in death too?
Space is not only really big, it's also mostly empty. That may be why they call it "space".
/Oh, and it takes a lot of mass to block gamma rays - a 1 cm thick lead panel will only block half of the photons.
Help stamp out iliturcy.
Just to be clear while there have been some correlations between super-nova and GRBs, they are not confirmed to be from any single source. None have occurred within our Galaxy during the modern era.
Photons with different wavelengths carry more or less energy depending upon frequency. High-Frequency is Higher-Engergy. E=MC^2. So, Higher Energy Photons are affected greater by gravity. Are they not?
Over-the-top Response Guy! Giving "Over-the-Top Responses" since 1970.
Funny... I sent the link to a friend who does GRB-related research, and she said "thanks, I already know about it though, I'm one of the authors" :). Apparently there are 210 authors on that paper though. Imagine coordinating that.
Anyway, I don't know a thing about astrophysics so that's about all I can contribute to this discussion.
Guess I should shut the fuck up about something that is not my area of expertise! Sorry about that!
Over-the-top Response Guy! Giving "Over-the-Top Responses" since 1970.
The brother JUST THOUGHT it took longer. And No, he's a bogart.
And here I was, all ready to welcome our new overlords...