CERN Experiment Indicates Faster-Than-Light Neutrinos

intellitech writes "Puzzling results from Cern, home of the LHC, have confounded physicists — because it appears subatomic particles have exceeded the speed of light. Neutrinos sent through the ground from Cern toward the Gran Sasso laboratory 732km away seemed to show up a few billionths of a second early. The results will soon be online to draw closer scrutiny to a result that, if true, would upend a century of physics. The lab's research director called it 'an apparently unbelievable result.'" Also on the AP wire, as carried by PhysOrg, which similarly emphasizes that the data are preliminary. Update: 09/22 20:43 GMT by T : Reader Curunir_wolf adds a link to the experiment itself, the Oscillation Project with Emulsion-tRacking Apparatus, or OPERA, which "was developed to study the phenomenon of neutrino transmutation (neutrinos changing from one type to another. The speed of the neutrinos, of course, was an entirely unexpected observation."

Comments

Einstein replied "Check your measurements, son"

[elrous0]

EOM

Re:Einstein replied "Check your measurements, son"

[bre_dnd]

It may still be a consistent measurement fault, but they've repeated it 15000 times. FTFA: "The team measured the travel times of neutrino bunches some 15,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery."

Re:Einstein replied "Check your measurements, son"

[MozeeToby]

No kidding, extraordinary claims require extraordinary evidence, and this is one mother of an extraordinary claim. Unlike most "fast than c" research that the media distorts, it actually sounds like it would be possible to transmit information using this effect, which essentially upends either relativity or causality. But, these aren't just some cranks doing experiments in their basements, and they are appropriately guarding their choice of words to emphasis the preliminary nature of the research which is a good sign. Hopefully the experiment wasn't too expensive and difficult to perform so we can get some people started on replicated (or refuting) the results.

Re:Einstein replied "Check your measurements, son"

[optymizer]

Hold on, I just need to wipe the dust off of this LHC I keep in my garage and then we can try to replicate their findings.

Re:Einstein replied "Check your measurements, son"

[icebike]

Regardless of how many times you repeat a measurement with a faulty ruler, the measurements are still wrong.

How precisely did they measure the 732km?

Re:Einstein replied "Check your measurements, son"

[MozeeToby]

Fermilab has a similar setup which should be able to test the results. So does an experiment in Japan, T2K, but they aren't running at the moment because of the tsunami. The actual experiment shouldn't be too hard to do if you have the equipment to make a beam of neutrinos, just point them at a detector and fire away and see how long time of flight was, which means they could probably start working on it fairly soon, though it will probably take months or years to get enough data points to be statistically significant.

Re:Einstein replied "Check your measurements, son"

[Anonymous Coward]

Which they point out in the article you didn't read.

"But the group understands that what are known as "systematic errors" could easily make an erroneous result look like a breaking of the ultimate speed limit, and that has motivated them to publish their measurements."

Re:Einstein replied "Check your measurements, son"

[Anonymous Coward]

They must have overlooked this point. Usually only senior/nobel level reasearchers can understand the extremely complicated system of faulty rulers and suspicious measurement results. In my experience, turning the thing OFF and ON again, would have done it.

Re:Einstein replied "Check your measurements, son"

[Lisandro]

How precisely did they measure the 732km?

Why, by closely watching oxens plough!

Re:Einstein replied "Check your measurements, son"

[Liquidrage]

So you're saying there's an 18m wormhole that makes these things get there "faster" than light. Or that they aren't capable of measuring to within 18 meters at that scale? I'd say that isn't very likely and I'd have a hard time imagining it. What I could imagine is that there's a mistake somewhere or equipment issue possibly. But repeated 15k times, and I fully trust the people at CERN OPERA to measure within 18m.

Re:Einstein replied "Check your measurements, son"

[Blade]

Yeh, I guess they never thought to check those two variables?

Re:Einstein replied "Check your measurements, son"

[ATestR]

I seriously doubt that they would have an 18 meter bust, even if they were surveying using 1950's surveying equipment. Errors that creep in using simple trigonometry are on the order of 1:100,000. GPS is a whole lot more accurate.

Re:Einstein replied "Check your measurements, son"

[History's Coming To]

GPS will do it accurately enough. It's a 17m "error" on the part of the neutrinos, and GPS has an appreciably higher resolution than that. It's the "neutrino bunches" I'm looking at for the experimental error - this could be one of the leading-edge effects that's already known about with photons - the leading edge can arrive faster than c, but the rest of the packet is slowed down so the velocity averages out at c. Still, even if this is the explanation it would be the first time it's been observed in a massive particle as far as I know.

Re:Einstein replied "Check your measurements, son"

[Toonol]

Of course, but these aren't crackpots screaming that modern physics is wrong. They're getting puzzling results, even after doublechecking, so they're asking others to verify. This is the by-the-book scientific process.

Re:Einstein replied "Check your measurements, son"

[shutdown -p now]

the knowledge that is the cornerstone of modern physics, knowledge that has been tested time and time again and found true, is upturned by one experiment?

Well, it's not like it never happened before...

If their finding is correct, it doesn't mean that previous experiments were wrong. It just means that things are more complicated than we thought them to be. It's a darker side of the Occam's Razor - you get rid of unnecessary things, sure, but how do you determine whether they are unnecessary? why, based on your experimental input - you need the simplest model that can explain the results that you see, and predict future results when you test it. Problem is, your experiments might not be covering some edge case, and therefore you didn't see the complete picture - and oversimplified your theory.

Re:Einstein replied "Check your measurements, son"

[MightyMartian]

Well, the proof, if you will, is that the faster anything travels, the more massive it becomes, and thus the more energy is required to accelerate it faster. Basically, any object that accelerates to c would become infinitely massive, or to put it another way, it would require an infinite amount of energy. In short, you cannot accelerate things to the speed of light. Photons basically come into existence at the speed of light.

Since neutrinos do have a mass, it means that CERN couldn't have accelerated them to the speed of light, let alone faster. So either we have a mundane measurement error, or some new never-before seen physical effect has been observed. But considering how intimately linked c is to so many physical constants and laws, I'd say whatever has happened cannot have violated this most essential precept, though beyond the "our ruler is screwy", the possible alternatives make one's head swim.

Re:Einstein replied "Check your measurements, son"

[Baloroth]

Actually, according to Ars Technica, Fermilab got a similar result, but threw it out because the margin of error was too large. I'm guessing a lot of attention will be focused on neutrinos now.

Re:Einstein replied "Check your measurements, son"

[Savantissimo]

"What's the alternative?"

The alternative is not that Einstein was wrong, but that neutrinos have imaginary mass rather than real mass. This is consistent with observations. We can't measure neutrino mass in experiments, only mass squared, and the error bars on those measurements persistently include some small negative numbers. (And some of these measurements virtually exclude any positive mass^2 values. Other measurements purporting to exclude negative mass^2 values may be the result of over-correction and wishful thinking.)

Imaginary-mass particles are consistent with relativity and were first theorized in the 1960s and given the name "tachyons". High-energy tachyons move near the speed of light; low-energy tachyons move at unlimited velocities. This accounts for the fact that the neutrinos from the 1987A supernova were only 18 hours ahead of the light from the explosion, despite the distance -- they were extremely high energy tachyons.

If neutrinos are tachyons, this could account for a couple of odd things about them - the exceptionally low cross section (likelihood of interaction) and their oscillating between different flavors (electron, muon, tau). Exactly how is a job for the theoreticians, but it seems to me that a neutral particle moving effectively backward in time and at unlimited velocities coupled with low energies is not often going to interact, and imaginary mass could be likened to a rotation or oscillation, much like many other things involving imaginary numbers in physics.

Physicist John Cramer talked about the idea back in 1992 in his Analog column: Neutrino Physics: Curiouser and Curiouser (Alternate View Column AV-54)

of the six most recent experimental determinations of neutrino mass, all have given negative values of the mass-squared to within the statics of the measurements. The experimental observation is that in the vicinity of the end point the yield of electrons lies above the zero-mass line, while for neutrinos with non-zero real mass, the electron yield should lie below this line. The measured mass-squared values are negative to an accuracy of several standard deviations in the most recent of these experiments.

These experimenters have been strangely quiet about mass-squared measurements with negative values. If the results had been positive by the same amount, the literature would be filled with claims that a non-zero value for the neutrino mass had been established. But a negative mass-squared is not something that can be easily publicized.

You obtain the measured mass value from a mass-squared measurement by taking the square root of the measured value. However, the square root of a negative number is an imaginary number. Thus the measurements could, in principle, be taken as an indication that the electron neutrino has an imaginary mass.

What are the physical implications of a particle with an imaginary rest mass? Gerald Feinberg of Columbia University has suggested hypothetical imaginary-mass particles which he has christened "tachyons". Tachyons are particles that always travel at velocities greater than the speed of light. Instead of speeding up when they are given more kinetic energy, they slow down so that their speed moves closer to the velocity of light from the high side as they become more energetic. Feinberg argued that since there are no physical laws forbidding the existence of tachyons, they may well exist and should be looked for.

Here's a link to another, slightly more technical look at the idea: Neutrinos Must be Tachyons by Eue Jin Jeong. Googling "neutrino tachyon" also turns up several previous discussions.

CERN IS faster than light

[JetScootr]

I searched for 'faster than light' on the CERN website, got articles posted in 2012, 2014. They put this new discovery to work right away!

Yay BBC News!

[il1019]

This was a rational piece without too many sensationalist remarks! How do we show them we appreciate decent scientific writing as opposed to the crap we normally get?

Re:Yay BBC News!

[StripedCow]

Click on the advertisements.

Re:That small?

[Daetrin]

And if it's actually an accurate result then it doesn't matter how small the value is. As soon as you break the speed of light by _any_ amount then the theoretical doors are wide open. According to Einstein breaking the speed of light by even just one nanosecond is _exactly_ as impossible as Star Trek variety warp speed.

time travel....

[thephydes]

There was a young lady named bright : who could travel much faster than light : She went out one day : in a relative way: and came back the previous night.

What speed?

[jeti]

Was it faster than the speed of light in the given medium or faster than the speed of light in vacuum?

Re:Which speed of light

[_0xd0ad]

The speed of light in a vacuum (c) is a constant. The speed of light in a non-vacuum is not.

What about a supernova?

[hort_wort]

Neutrinos have been observed coming from supernovae from light years away. There would have been a very noticeable time difference between the neutrinos and the light at that distance if this were true. (Any astrophysicists about to verify this?)

I'm skeptical. I think it was likely a wiring problem. It only takes a few centimeters of wire to make a 60ns delay, and these experiments are notorious for using many wires.

Re:What about a supernova?

[radtea]

Neutrinos have been observed coming from supernovae from light years away. There would have been a very noticeable time difference between the neutrinos and the light at that distance if this were true. (Any astrophysicists about to verify this?)

SN1987A results were consistent with neutrinos moving at c, although the precise detection time of the optical signal was some hours after the neutrino signal (which was found in subsequent analysis.) John Simpson tried to use an argument about times and average energies to argue for a slightly later than expected arrival time, to support his 17 keV neutrino.

These results are 60 ns in about 2 ms, or a factor of 0.00003. The LMC (home of SN1987A) is 160,000 light years away, so this would have the neutrino signal arriving several years ahead of the optical signal.

Ergo, your skepticism is justified. Good call on the comparison measure.

Error in measuring distance perhaps ?

[adisakp]

The detector is 732km away for the emitter and light travels at 299 792 458 m/s. In one billionth of a second, light only travels 29.9 cm. If they are off in the precision of measuring a 732km distance by even as little as 30 cm (~1ft), then their timings will be off by 1 billionth of a second.

Re:Error in measuring distance perhaps ?

[KingofSpades]

They claim they are confident about the distance to within 20 cm.

Re:First Post

[Tanktalus]

Consensus != universal fact. Consensus == our best understanding of universal fact. There's a difference. Real science is always open to upending.

Re:Why is this impossible?

[LateArthurDent]

And why would this result be impossible?

It's impossible according to current theories. It's not impossible that current theories are wrong, but very highly improbable to be wrong in this way, given the amount of corroboration we have for the speed of light being an absolute limit and for the time-dilation effects, which would cause faster-than-light particles to violate causality.

Nevertheless, the data is the data, and that's why they're publishing it. Somebody else will find a measurement error (most likely) or we'll get exciting new physics (much less likely, but would be pretty awesome).

Many have posted that the instruments were flawed or the scientists made a mistake, but not too long ago scientists were 100% certain that the world was flat too.

Actually, I'd say that was very long ago. Considering Eratosthenes not only knew that the Earth was round, but was able to calculate the circumference to remarkable accuracy way back in ~200 BC. Note that it wasn't him that decided the Earth was round, that was already common knowledge. He figured out the circumference.

Just because scientists currently believe that nothing can go faster than the speed of light doesn't make it so. Our views of the universe are always changing and saying that a result is "impossible", no matter how unlikely the result, is a bit short sided.

That's true, however as many others have pointed out, extraordinary claims require extraordinary evidence. A single experiment just isn't enough. If we have sufficient confirmation of faster than light effects, scientists will most certainly welcome the result. Unexpected data opens up new opportunities for lots of papers. Scientists live for that, literally. It's what puts food on the table :)

Re:distribution

[coolmadsi]

Eh, this happens every few years... what tends to be the case is someone gets a hold of one of the charts where velocities were recorded and due to measurement issues there is a probability curve rather then a simple line... normally you use the curve to determine what the actual velocity was, but you always get at least a couple yahoos that look at the curve, notice that one of the tails goes above C and get all excited that something is going faster then light.

Good thing they are are going to put the findings online to be checked then (they have been looking for errors and have been unable to find any so far).

The result - which threatens to upend a century of physics - will be put online for scrutiny by other scientists.

In the meantime, the group says it is being very cautious about its claims.

"We tried to find all possible explanations for this," said report author Antonio Ereditato of the Opera collaboration.

"We wanted to find a mistake - trivial mistakes, more complicated mistakes, or nasty effects - and we didn't," he told BBC News.

"When you don't find anything, then you say 'Well, now I'm forced to go out and ask the community to scrutinise this.'"

Source: http://www.bbc.co.uk/news/science-environment-15017484

Re:Not so fast...

[epine]

To me a nanosecond seems pretty big. I've spent a chunk of my time over the last couple of years designing consumer circuits sensitive to changes of 10ps in signal arrival time due to changes in the surrounding bulk dielectric.

You haven't lived until you've read a datasheet with the performance spec:

Deterministic jitter: 300 fs.

Probably a PECL part, but still.

And no, they're not using an instantaneous tau to approximate a decay distribution. Anyone who has ever cooked popcorn knows better than that.

Re:Not so fast...

[ChinggisK]

And no, they're not using an instantaneous tau to approximate a decay distribution. Anyone who has ever cooked popcorn knows better than that.

Completely wrong. I've cooked popcorn and I have no idea what "instantaneous tau to approximate a decay distribution" means.