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Merged Puzzling results from CERN

Sol, Thanks for the explaination. The LHC is a wonderment to me. Seems that nothing IS sacred.
 
jsfisher said:
How are all the gravitational effects calculated, especially with the Alps sitting above the path?
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Do you mean gravitational effects on the neutrinos? I think those are negligible - they're relativistic, so there will just be a tiny curvature of the path due to the gravity of the earth.
 
sol invictus said:
Do you mean gravitational effects on the neutrinos? I think those are negligible - they're relativistic, so there will just be a tiny curvature of the path due to the gravity of the earth.
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I think I let myself get a little confused about somethings, and the question really was coming from a position of ignorance. The reference frame is the Earth, so the observed speed of the neutrino isn't bothered by any gravitational time-dilation effects the neutrino might experience. Correct?
 
jsfisher said:
I think I let myself get a little confused about somethings, and the question really was coming from a position of ignorance. The reference frame is the Earth, so the observed speed of the neutrino isn't bothered by any gravitational time-dilation effects the neutrino might experience. Correct?
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If you have a good model of the Earth's gravitational potential (they exist), then you can talk about the gravitational time dilation between the emitter and the detector, which may affect measurements. But Φ/c² ~ 7E-10 on Earth's surface, so it's hard to see what kind of kind of relevance gravitational time dilation would have to a discrepancy of the claimed magnitude.
 
jsfisher said:
I think I let myself get a little confused about somethings, and the question really was coming from a position of ignorance. The reference frame is the Earth, so the observed speed of the neutrino isn't bothered by any gravitational time-dilation effects the neutrino might experience. Correct?
Click to expand...

Oh, I see. Well, if CERN and Gran Sasso were at significantly different values of the gravitational potential, that could cause some complications (because for example clocks would run at different rates and so would not stay synced). But I don't think those effects are important here; they're too small (they are important for the GPS system, though).
 
Vorpal said:
But Φ/c² ~ 7E-10 on Earth's surface, so it's hard to see what kind of kind of relevance gravitational time dilation would have to a discrepancy of the claimed magnitude.
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It is hard to see, but you do have to be a little careful - the difference could accumulate over time. That's why it matters for the GPS satellites - their clocks are adjusted to run at a different rate than earth clocks, to compensate for the combination of gravitational and Lorentz time dilation, and even so I think they have to be re-synced periodically.

But I agree, I don't see how that could come into play here.
 
Do you care to explain how this is any different than electrons exceeding c in dielectric water?
 
sol invictus said:
It is hard to see, but you do have to be a little careful - the difference could accumulate over time. That's why it matters for the GPS satellites - their clocks are adjusted to run at a different rate than earth clocks, to compensate for the combination of gravitational and Lorentz time dilation, and even so I think they have to be re-synced periodically.
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You know, for all the gigabytes of GPS data I have, I really don't know if the clocks were deliberately tweaked to put out their reference signal at some terrestrial rate (10.23 MHz, I think). I'll try to check on it tomorrow. I suspect that the adjustment is actually imbedded in the definitions of the parameters included in the nav messaage, though.

But I can address the update thing with more confidence. The clock correction is part of the nav message that the spacecraft continuously sends. IIRC, the nav messages (including clock correction updates) are typically updated every 24 hours, though there's no technical reason they couldn't be updated much more or less often. Of course, there are practical considerations.

[/GPS]
 
Discovery of tachyons reported?

http://www.livescience.com/16183-faster-speed-light-physics-breakthrough.html

The article describes neutrinos moving faster than 15c or 15 times the speed of light in a vacuum. I don't know why they are reporting that special relativity must be violated here because it simply could be tachyons depending on how the experiments were conducted.

Particles can permanently travel faster than light according to special relativity, but they cannot accelerate past the light barrier. Unless they observed acceleration beyond the speed of light, why couldn't they speculate that tachyons have been found?
 
sol invictus said:
According to the known laws of physics, quantum effects cannot transmit information of any kind faster than light, full stop.
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That's what the standard answer is, but in the program I saw, music was transmitted and the researcher said, he thought the music was indeed information.

I'm not certain either way. But I found the researcher credible.
 
I'm still stuck on the "mass going to infinite and requiring infinite energy when it reaches the speed of light" thing. That sounds like the kind of thing you'd notice long before anything else.
 
Skeptic Ginger said:
That's what the standard answer is, but in the program I saw, music was transmitted and the researcher said, he thought the music was indeed information.
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Music certainly contains information. But I'm extremely skeptical of the claim that music was transmitted faster than the speed of light. Do you have a cite for that?
 
Astrodude said:
http://www.livescience.com/16183-faster-speed-light-physics-breakthrough.html

The article describes neutrinos moving faster than 15c or 15 times the speed of light in a vacuum. I don't know why they are reporting that special relativity must be violated here because it simply could be tachyons depending on how the experiments were conducted.
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Never was it so easy to debunk.

The particles were observed to be traveling at about 20 parts per million faster than the speed of light.

Very interesting, of course, but still fairly small. It could easily be an error in measurement, either of the experiment itself or of the accepted value of c. It's already known that the signal speed of light in a vacuum is a bit slower than c because of interactions with virtual particles due to quantum fluctuations in the vacuum. It's also known that neutrinos interact only very weakly.
 
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