Slashdot Mirror
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."
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."
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?
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.
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.
This Space Intentionally Left Blank
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.
How precisely did they measure the 732km?
Why, by closely watching oxens plough!
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.
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
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.
Blasphemy is a human right. Blasphemophobia kills.
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.
Please consider this account deleted, I just can't be bothered with the spam anymore.
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.
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.
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.
"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)
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.
"Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery?" - Patrick Henry