[gwnn]

btw just did a very simple calculation and 60ns is equivalent to a distance of 18 metres at the speed of light, and 1/40 000 of the total time.

The paper is here: http://static.arxiv....f/1109.4897.pdf

They claim an error of about +/- 10 ns, or so, if I'm reading it correctly.

[barmar]

 gwnn, on 2011-September-26, 06:02, said:

btw just did a very simple calculation and 60ns is equivalent to a distance of 18 metres at the speed of light, and 1/40 000 of the total time.

Ouch, there goes my tunneling theory. I have no idea how to do the calculations, but my guess is that you could probably count the number of particles on earth that would tunnel that far on your fingers.

[PassedOut]

Faster-than-Light Neutrino Puzzle Claimed Solved by Special Relativity

Quote

So what is the satellites' motion with respect to the OPERA experiment? These probes orbit from West to East in a plane inclined at 55 degrees to the equator. Significantly, that's roughly in line with the neutrino flight path. Their relative motion is then easy to calculate.

So from the point of view of a clock on board a GPS satellite, the positions of the neutrino source and detector are changing. "From the perspective of the clock, the detector is moving towards the source and consequently the distance travelled by the particles as observed from the clock is shorter," says van Elburg.

By this he means shorter than the distance measured in the reference frame on the ground.

The OPERA team overlooks this because it thinks of the clocks as on the ground not in orbit.

How big is this effect? Van Elburg calculates that it should cause the neutrinos to arrive 32 nanoseconds early. But this must be doubled because the same error occurs at each end of the experiment. So the total correction is 64 nanoseconds, almost exactly what the OPERA team observes.

[Winstonm]

 PassedOut, on 2011-October-15, 12:26, said:

Faster-than-Light Neutrino Puzzle Claimed Solved by Special Relativity

Well, that certainly refutes the lyrics, "Ti-i-i-i-ime is on my side, yes it is."

[barmar]

The last paragraph is the best:

Quote

If it stands up, this episode will be laden with irony. Far from breaking Einstein's theory of relatively, the faster-than-light measurement will turn out to be another confirmation of it.

What got me was the earlier comment: "the tricky part is keeping the clocks at either end exactly synchronised." Doesn't Special Relativity say that there's no such thing as synchronized clocks?

[hotShot]

That special relativity idea seems to be wrong.

Dr. T. Feldmann from the PTB Braunschweig who was involved in developing the method of time measurement claims that relativistic effects were taken into account and that Ronal A.J van Elburg made a mistake himself by adding signal- and satellite speed in a classical way instead of a relativistic way.

So the mystery is still on.

[BunnyGo]

 barmar, on 2011-October-18, 15:31, said:

The last paragraph is the best:

What got me was the earlier comment: "the tricky part is keeping the clocks at either end exactly synchronised." Doesn't Special Relativity say that there's no such thing as synchronized clocks?

No, what it says is that "simultaneity is relative". Since clocks being synchronous is a series of simultaneous events (ticking every second together) this is a relative thing. The difficulty is synching them in your reference frame when you can't actually easily see both of them at the same time. This was (provisionally) their error.

[semeai]

 hotShot, on 2011-October-18, 15:51, said:

That special relativity idea seems to be wrong.

Dr. T. Feldmann from the PTB Braunschweig who was involved in developing the method of time measurement claims that relativistic effects were taken into account and that Ronal A.J van Elburg made a mistake himself by adding signal- and satellite speed in a classical way instead of a relativistic way.

So the mystery is still on.

Do you have a link?

 barmar, on 2011-October-18, 15:31, said:

What got me was the earlier comment: "the tricky part is keeping the clocks at either end exactly synchronised." Doesn't Special Relativity say that there's no such thing as synchronized clocks?

 BunnyGo, on 2011-October-18, 15:54, said:

No, what it says is that "simultaneity is relative". Since clocks being synchronous is a series of simultaneous events (ticking every second together) this is a relative thing. The difficulty is synching them in your reference frame when you can't actually easily see both of them at the same time. This was (provisionally) their error.

Maybe a simpler way of putting it: Two clocks that are at rest with respect to each other have a notion of being synchronized.

[hotShot]

 semeai, on 2011-October-18, 18:45, said:

Do you have a link?

http://heise.de/-1362506

As to "Can apparent superluminal neutrino speeds be explained as a quantum weak measurement?"

M V Berry, N Brunner, S Popescu & P Shukla answer that with "Probably not."

http://arxiv.org/ftp...0/1110.2832.pdf

[semeai]

 hotShot, on 2011-October-18, 15:51, said:

That special relativity idea seems to be wrong.

Dr. T. Feldmann from the PTB Braunschweig who was involved in developing the method of time measurement claims that relativistic effects were taken into account and that Ronal A.J van Elburg made a mistake himself by adding signal- and satellite speed in a classical way instead of a relativistic way.

So the mystery is still on.

 hotShot, on 2011-October-18, 23:01, said:

http://heise.de/-1362506

Thanks for the link. It makes complete sense that the people who think about time synchronization using GPS would already take into account relevant effects like this. After all, as we all know from xkcd, even general relativity is necessary for GPS to be accurate.

That said, I'm not sure why there's the comment about there being an error. Maybe the reporter misunderstood, or put the researcher on the spot and it was a throwaway comment? Equation (2) in Elburg's paper is correct; he's not adding velocities. An analogous equation shows up as equation (8) in the paper cited in that news article as already taking into account the effect.

[mike777]

 semeai, on 2011-October-19, 09:16, said:

Thanks for the link. It makes complete sense that the people who think about time synchronization using GPS would already take into account relevant effects like this. After all, as we all know from xkcd, even general relativity is necessary for GPS to be accurate.

That said, I'm not sure why there's the comment about there being an error. Maybe the reporter misunderstood, or put the researcher on the spot and it was a throwaway comment? Equation (2) in Elburg's paper is correct; he's not adding velocities. An analogous equation shows up as equation (8) in the paper cited in that news article as already taking into account the effect.

so at this point there is an experimental error or not?

[semeai]

 mike777, on 2011-October-19, 21:25, said:

so at this point there is an experimental error or not?

No experimental error confirmed yet I guess. My take from the sources mentioned in this thread: The paper giving the "correction" didn't make a mistake in its physics, but the original paper presumably used GPS time calibration that already included the physics "correction," according to some guy who knows about GPS time calibration.

[hotShot]

 semeai, on 2011-October-19, 22:01, said:

No experimental error confirmed yet I guess. My take from the sources mentioned in this thread: The paper giving the "correction" didn't make a mistake in its physics, but the original paper presumably used GPS time calibration that already included the physics "correction," according to some guy who knows about GPS time calibration.

While I can't say anything about the physics involved., I can tell you that the PTB is the german equivalent of the NIST. One of it's main objectives is to synchronize clocks and to evaluate and develop methods for accurate time measurement .
"This guy" finished his ph.d. thesis on "Advances in GPS based Time and Frequency Comparisons for Metrological Use" this year.
Part of this was " Improved GPS-Based Time Link Calibration" to be found here:
http://www.ptb.de/cm...ROA_and_PTB.pdf

So I think that he knows about this stuff.

[semeai]

 hotShot, on 2011-October-20, 00:17, said:

While I can't say anything about the physics involved., I can tell you that the PTB is the german equivalent of the NIST. One of it's main objectives is to synchronize clocks and to evaluate and develop methods for accurate time measurement .
"This guy" finished his ph.d. thesis on "Advances in GPS based Time and Frequency Comparisons for Metrological Use" this year.
Part of this was " Improved GPS-Based Time Link Calibration" to be found here:
http://www.ptb.de/cm...ROA_and_PTB.pdf

So I think that he knows about this stuff.

I didn't mean "some guy" to be disparaging. However, as you imply, "an expert on" would have been better wording than "some guy who knows about."

By way of lame excuse, maybe I can erroneously suggest that I have a high bar for using the word "know(s)."

[barmar]

If high-energy physics were easy, everyone would do it.

[BunnyGo]

I'd still back Einstein (as per several XKCD strips) but apparently the experiment has been repeated.

Oh, and doesn't

Quote

The odds have shrunk that Einstein was wrong about a fundamental law of the Universe.

mean that it's less likely that Einstein was wrong? Why put a sentence like that in front of an article describing how an experiment "showing" he was wrong has been repeated?

[BunnyGo]

One question for the physicists (or physics knowledgeable people). If the neutrinos really are going faster than light, shouldn't they arrive before they are produced? Or is the theory that relativity is completely wrong with regards to faster than light travel and its effects?

[S2000magic]

 BunnyGo, on 2011-November-18, 10:37, said:

Oh, and doesn't

"The odds have shrunk that Einstein was wrong about a fundamental law of the Universe"

mean that it's less likely that Einstein was wrong? Why put a sentence like that in front of an article describing how an experiment "showing" he was wrong has been repeated?

Not the way it's written; if it had said that the odds against Einstein being wrong had shrunk, it would mean that it's less likely that he was wrong.

(In your defense, the author of the sentence you quoted probably meant the odds against Einstein being wrong, and fouled it up; most laymen, in my experience, don't understand that the common (mathematical, statistical) use of "odds" refers to odds against something happening.)

[BunnyGo]

 S2000magic, on 2011-November-18, 11:34, said:

Not the way it's written; if it had said that the odds against Einstein being wrong had shrunk, it would mean that it's less likely that he was wrong.

(In your defense, the author of the sentence you quoted probably meant the odds against Einstein being wrong, and fouled it up; most laymen, in my experience, don't understand that the common (mathematical, statistical) use of "odds" refers to odds against something happening.)

Thanks for clearing that up, I was suspicious about the use of the term. So much for all the probability theory I took in grad school. We never discussed "odds" as a term like this.

[gwnn]

 BunnyGo, on 2011-November-18, 11:26, said:

One question for the physicists (or physics knowledgeable people). If the neutrinos really are going faster than light, shouldn't they arrive before they are produced? Or is the theory that relativity is completely wrong with regards to faster than light travel and its effects?

They should arrive in imaginary time, or not? There will be some negative numbers under some square roots I guess.