Slashdot Mirror
Can Relativity Explain Faster Than Light Particles?
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."
c++
Nice try.
Sincerely,
Einstein
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.
The researchers made no such claim! In fact they explicitly said they disbelieved they saw faster than light particles, and that they thought their data was faulty somewhere. But what they DID do is ask for other scientists to check their data and find their data, and if possible recreate the experiment to help track down where the error was.
THIS IS CORRECT SCIENTIFIC PROCEDURE!
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.
All the world's a CPU, and all the men and women merely AI agents
Are they using some other measurement of "speed" that isn't distance / time? It seems that slowing time down and going the same "speed" has the same net effect as going faster than the speed of light.
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.
That said, another poster pointed out 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.
They did consider it, the critic had a brain fail and misunderstood their paper. The researchers are doing him a kindness and 'clarifying' it for him, even though everyone else got that they had, in fact, accounted for this.
"Who is the Journal of Quantum Physics going to believe?" --Stephen Hawking
They didn't have to raise the speed of light; they just raised it a semitone.
That's right. The universal constant for the speed of light is c#.
Welcome to the Panopticon. Used to be a prison, now it's your home.
If a particle has mass, its velocity will be less than C. If a particle has no mass, its velocity will equal C.
E = mc^2 refers to rest energy, it is the amount of energy you get if you convert an unmoving mass directly into energy. Photons, having no mass, have no rest energy by definition. 0 * c * c = 0. E / 0 is undefined, not infinite. Literally the only line of your reply without a significant error is the first one. E=mc^2 has nothing to do with the assertion that massless particles must travel at c, that comes from other parts of special relativity.
Yes. Contaldi has made a tit of himself with this critique. The real error is likely to be very subtle.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
I worked it out half way.
Then I worked out half of the remaining math.
Then I...
An important change for education.
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.
If C# is now the speed of light- does that mean that Java exceeds the speed of light?
No, Java is still slow.
It's explained by Rudolf the Redshift Reindeer.
Escher was the first MC and Giger invented the HR department.
Steve ?
Religion is what happens when nature strikes and groupthink goes wrong.
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.
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)
The arxiv blog recently had a roundup of papers discussing this: http://www.technologyreview.com/blog/arxiv/27212/ 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
Find free books.