Can Relativity Explain Faster Than Light Particles? 315
gbrumfiel writes "Two weeks ago, researchers claimed particles called neutrinos were travelling faster-than-light and violating the laws of special relativity. But now it looks as though general relativity might be behind the experiment's unusual result. An independent analysis claims that the original experiment, known as OPERA, failed to take into account differences in earth's gravitational field between the neutrino source and the OPERA detector. As Nature News reports, gravity can distort time according to Einstein's theory, and the effect could explain why neutrinos appear to arrive 60 nanoseconds ahead of schedule. The OPERA team is now reviewing the new analysis."
The speed of light (Score:1, Informative)
It's not just a good idea, it's the law.
The OPERA team is NOT reviewing the new analysis. (Score:5, Informative)
They are reviewing their own paper to make their methods clear. FTFA:
"Dario Autiero of the Institute of Nuclear Physics in Lyons (IPNL), France, and physics coordinator for OPERA, counters that Contaldi's challenge is a result of a misunderstanding of how the clocks were synchronized. He says the group will be revising its paper to try to make its method clearer."
Meaning: Contaldi didn't understand how OPERA did it, and thought they had commited a somewhat stupid mistake. OPERA says they didn't make that error, and that they'll rewrite that part of the paper to make this clear. In other words, this is not news at all.
WRONG! (Score:5, Informative)
THIS IS CORRECT SCIENTIFIC PROCEDURE!
Re:Seriously? (Score:5, Informative)
I hate to say this, because I know it's probably painfully obvious to most people, but I have no idea what you're talking about.
He's talking about GPS. In order for the triangulation to work correctly, relativity must be taken into account [ohio-state.edu].
That said, another poster pointed out [slashdot.org] that the researchers apparently did account for the effects of gravity when synchronizing their clocks. The paper just wasn't sufficiently clear on that point, and they're rewriting that section.
Re:I called it (Score:4, Informative)
If a particle has mass, its velocity will be less than C. If a particle has no mass, its velocity will equal C.
Re:I called it (Score:5, Informative)
no experiment has yet to show that photons have no mass.
That's because it's a very hard thing to show. What they have shown experimentally is that the mass has to be smaller than 10^-18 eV/c, which is 1.782662 x 10^-54 kg, which is 1 / 10^-24th the mass of an electron which is by far the lightest particle predicted.
And I'd be interested to hear how E=mc^2, a central component of special relativity, causes it to conflict with general relativity. Do tell!
Basically the sun revolves around the earth - what ever we think now is correct no matter what anyone else says.
We used to think the earth was flat, and we were wrong. Then we thought the earth was a sphere and we were wrong (it's actually an oblate spheroid). But if you think believing the earth is a sphere is just as wrong as thinking the earth is flat, then you're wronger than the both of them. (paraphrased from Asimov). We know Newtonian physics is wrong, relativity significantly improves on the accuracy of Newtons predictions. That doesn't mean I drop an apple and expect it not to fall because Newton was wrong. Similarly, we know that relativity is wrong (the predictions break down in several extreme situations), but that doesn't mean that I expect E=mc^2 to be wrong tomorrow or time dilation to be proven wrong or any of the other well known relativistic effects. They have been shown empirically to be correct to fractions of fractions of a percentage point, that evidence doesn't just go 'poof' when a more refined theory comes along.
Re:Now we know why (Score:4, Informative)
The bending of light by the deformation of space-time is completely unlike or related to the refraction of light. The first is light following the curvature of space, and all frequencies of light would follow the same path (remember Galileo's experiment from the tower of Pisa? Two different particles are accelerated by gravity in precisely the same way.) The second is a wave function across the boundary of two different optical media. Waves with longer period (lower frequency) are bent more than waves of shorter period (higher frequency.) You can do this experiment with water in a wave tank and see the phenomenon clearly. Unrelated phenomena.
Supernova observation discounts FTL neutrinos. (Score:4, Informative)
After I saw this quote I figured they'd have to find some error in their observations. (Emphasis added.)
"...If the observation is confirmed, it may be the most important discovery in science in the last 100 years.
"However, a big fly in the ointment is the supernova in the Large Magellanic Cloud, which sits just outside our galaxy 168,000 light-years from Earth. It was first seen by the naked eye on February 24, 1987. Three hours before the visible light reached Earth, a handful of neutrinos were detected in three independent underground detectors. If the CERN result is correct, they should have arrived in 1982. So, if I were a wagering man, I would bet the effect will go away because of some systematic error no one has yet been able to think of."
(Quote stolen from Quark Soup [blogspot.com])
a bunch of papers (Score:5, Informative)
The arxiv blog recently had a roundup of papers discussing this: http://www.technologyreview.com/blog/arxiv/27212/ [technologyreview.com] They fall into three groups: (1) Suggestions of how the experiment might have given a wrong result. (2) Theoretical arguments that constrain the interpretation and make the result seem implausible if taken at face value. (3) Theoretical papers saying what it could mean if it really was new physics. The Nature article seems to show that the Contaldi paper was based on a misunderstanding of how the experiment was done. However, the Nature article points to a new paper by Henri that wasn't included in the arxiv roundup: http://arxiv.org/abs/1110.0239 [arxiv.org]