CERN Experiment Indicates Faster-Than-Light Neutrinos 1088
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."
Re:Einstein replied "Check your measurements, son" (Score:5, Informative)
Re:Tachyons? (Score:4, Informative)
Re:Einstein replied "Check your measurements, son" (Score:4, Informative)
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:Yay BBC News! (Score:2, Informative)
At the very bottom right of the page there's a grey Contact Us link (yeah, I know - it's not that obvious). Click that then select General Comments. I work for the Beeb - we really do appreciate feedback, especially the positive kind :)
Re:Which speed of light (Score:5, Informative)
The speed of light in a vacuum (c) is a constant. The speed of light in a non-vacuum is not.
Re:Yay BBC News! (Score:5, Informative)
Click on the advertisements.
1.06 times the speed of light +- 0.21 (Score:2, Informative)
http://www.csa.com/discoveryguides/gravity/overview.php [csa.com]
Re:Einstein replied "Check your measurements, son" (Score:4, Informative)
According to the ABC article, the particles are showing up 60ns too early. If the particles were in fact traveling at light speed, that would simply mean the detector was about 18 meters closer to CERN than they originally thought. Considering differences in altitude, oblateness of the Earth, the detector is underground, and so on, it isn't hard to imagine an 18m position error over approximately 732,000 m distance measured or calculated.
Re:Error in measuring distance perhaps ? (Score:5, Informative)
Re:Einstein replied "Check your measurements, son" (Score:5, Informative)
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:distribution (Score:5, Informative)
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 [bbc.co.uk]
Re:Einstein replied "Check your measurements, son" (Score:3, Informative)
Re:Error in measuring distance perhaps ? (Score:4, Informative)
They say they've ran the experiment 15,000 times. I would imagine this does involve more than one calibration of instruments.
Re:Einstein replied "Check your measurements, son" (Score:5, Informative)
would we have noticed? (Score:4, Informative)
If we detected a neutrino pulse would we have a good enough estimate of direction to look for the light? Or even the notion that we *should* look for a pulse of light several years later in the same region of sky? If we did record both by happenstance, would anyone have correlated the two events? That is weird enough that I'm thinking they wouldn't.
Phase Velocity vs Group Velocity: C is Constant! (Score:4, Informative)
I am intimately familiar with the interaction of light with matter as a result of having been an avid Amateur Telescope Maker [geometricvisions.com] and Amateur Astronomer since the tender age of twelve.
This led to my acceptance to study Astronomy at Caltech in the Fall of 1982, where I was privileged to attend a non-credit class called "Physics X" that was taught by The Immortal Richard Feynman. You could ask him any question you wanted - it didn't have to be about Physics even - but the ensuing discussion had to be purely conceptual. Questions that would require Feynmen to work out equations on the chalkboard were not permitted.
One afternoon I pointed out to him that the phenomenon that light slows down as it passes through a medium just had to be wrong. When one examines any medium at a subatomic scale, it is mostly empty vacuum with some rare particles that have all been either proven or are suspected to be geometric points. (While Protons and Neutrons have a non-zero diameter, they are each composed of three quarks, which themselves are thought to be point particles.)
"Surely," I pointed out to Feynman, "When light passes through all this vacuous space inside a piece of glass, it always travels at precisely C! How could Snell's Law" - which yields the angle of refraction when light passes through the surface of a medium - "possibly be correct!"
I knew damn well that Snell's Law was correct, as Snell himself experimentally demonstrated the law hundreds of years ago. While he did not measure what the Speed of Light had to do with refraction, we have been able to measure light's speed for over a century.
Feynman replied that when light passes through matter, the charged particles in that matter oscillate in sympathy with the oscillations of the light's electomagnetic field. But because they are all in a bound state, and because accellerating charged particles causes them to emit light of their own, thereby carrying away energy and so dampening their sympathetic oscillation, the movements of the charged particles in matter is not quite in phase with the waves in the light passing through the medium.
Feynman concluded, "The light emitted by the charge particles in matter interferes with the light passing through the medium" - that is, wave peaks add to wave peaks, and so with troughs, while peaks and troughs together cancel each other - "so that the resulting combination of light waves only appears to move slower than C."
Thus the Photons are always moving at a constant velocity of C, but all the Photons in the medium interact so that passing a Photon through the medium will result in the exit Photon being delayed from the timing you would expect from when the entrance Photon entered the front surface. They key to understanding all this is that the entrance and exit Photons are NOT THE SAME PHOTON!
Feynman discusses this in a really lucid way, with rigorous mathematics, in Volume II of The Feynman Lectures on Physics. Volume II covers Electricity and Magnetism, Volume I covers Classical Mechanics - Newton's Laws of Motion and such - while the third volume does Quantum Mechanics. The set of three is expensive but are easy to read, even if you don't know much Calculus, and would be a good investment for any Slashdotter.
I was mortally embarrased to realize years later that I had asked Feynman a really basic, purely conceptual question whose completely rigorous answer led to him sharing the 1965 Nobel Prize with Tomanaga of Japan! Their Quantum Electrodynamics describes the interaction of light with electric charge with complete precision.
Feynman's formulation uses a conceptual drawing called a Feynman Diagram as a calculational and explanatory device. I don't know how Tomanaga formulated his Quantum Electrodynamics, but my understanding as that at first no one could understand why the two theories seemed quite different but always yielded the same numerical results. Some time later Freeman Dyson - Esth