Why is it so hard to think that something could travel faster than light?
Because much of science and technology (things that are known to work) is based on theories that implicitly assume the light speed limit*. It's not that we think all those things will stop working if we admit that something travels faster than light: they obviously won't. It's that an enormous number of diverse experiments have been successfully carried out with one thing in common: the light speed limit.
* And no, it doesn't work to add an asterisk and a footnote that says "Except neutrinos".
We have now just the possiblity they corrected some delay wrong (they forgetting to correct something isn't a viable explanation), or that the neutrinos are faster than light.
Or new physics (I haven't the faintest what, of course) that somehow explains the apparent superluminality. I'd put that ahead of actual superluminality but behind some sort of experimental error (Yes, I know these guys are really, really sharp, but superluminality contradicts special relativity).
Neutrinos have very tiny rest masses (about 2eV) and so are expected to travel at very nearly light speed when they have large energies (tens of GeV in this case) since E=(mv^2)/2.
>...the proton bunches where huge (milliseconds)...
About ten microseconds. Still huge compared to 60ns, though. On the other hand the luminosity was much higher than with the 1ns pulses in the recent experiment and so the S/N was higher. The new experiment rules out a bunch of error sources though, and the combination is pretty hard to argue with. I'll be skeptical of superluminality even when the result has been replicated elsewhere, but I will be expecting exciting new physics.
This is because the photons have to diffuse through the outer layers of the star while the neutrinos are unimpeded. The early arrivial of the neutrinos is exactly as predicted by supernova theory.
But there isn't enough room inside a politician's head for this sort of experiment (their egos, on the other hand, would easily suffice, if they weren't full of hot air).
>...MINOS uses a matched near detector / far detector layout...
I didn't know that. Thank you. That means that if the time precision of MINOS can be improved (presumably much cheaper than building a detector at the LHC) the detector-detector experiment I suggested elsewhere can be done soon.
...is to run the experiment with neutrino detectors at both ends, thus eliminating many of the variables involved with comparing the phase of the proton pulse string at the transmitter with the phase of the muon pulse train at the receiver. I assume that such an experiment is being planned right now, unless there is some reason obvious to physicists but not to me that it would be useless. This would, of course, be very expensive: I can understand not rushing into construction of such a system until all other avenues have been explored.
Even (as seems likely) that the neutrinos turn out not be exceeding c, I think that we will learn something interesting from this. I doubt that the explanation is a simple oversight or math error.
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Because much of science and technology (things that are known to work) is based on theories that implicitly assume the light speed limit*. It's not that we think all those things will stop working if we admit that something travels faster than light: they obviously won't. It's that an enormous number of diverse experiments have been successfully carried out with one thing in common: the light speed limit.
* And no, it doesn't work to add an asterisk and a footnote that says "Except neutrinos".
The OPERA team has answered Contaldi's criticism in the new paper and elsewhere with more details on their methods.
> ...didn't use any photons to check the distance...
I wouldn't say that. GPS uses photons (microwave ones) and modern surveying makes extensive use of lasers.
They only used fiber for some local measurements. The 730km was measured with surveying and GPS.
Or new physics (I haven't the faintest what, of course) that somehow explains the apparent superluminality. I'd put that ahead of actual superluminality but behind some sort of experimental error (Yes, I know these guys are really, really sharp, but superluminality contradicts special relativity).
Neutrinos have very tiny rest masses (about 2eV) and so are expected to travel at very nearly light speed when they have large energies (tens of GeV in this case) since E=(mv^2)/2.
Superluminal velocities are inexplicable.
> ...the proton bunches where huge (milliseconds)...
About ten microseconds. Still huge compared to 60ns, though. On the other hand the luminosity was much higher than with the 1ns pulses in the recent experiment and so the
S/N was higher. The new experiment rules out a bunch of error sources though, and the combination is pretty hard to argue with. I'll be skeptical of superluminality even when the result has been replicated elsewhere, but I will be expecting exciting new physics.
Sure. First thing they did is pass through the mass of the exploding star.
The 1987A "experiment" used several types of detectors but different types of neutrinos with different energies (lower). It got different results.
He's implying that they somehow forgot to include that 60m in their path length calculation.
Read the paper (cited upthread). They explain exactly how they made the measurements.
Cheaper to do that than to duplicate 1987A.
The supernova neutrinos. They travelled out from the center of the star.
Neutrino oscillation
But it was still one poorly-understood natural event that occurred in another galaxy.
That's ... pretty convincing.
> ...is this really as big a deal as people are making it out to be?
Yes.
> Isn't it quite possible that Einstein just rounded down when he was calculating 'c'? ;)
Einstein didn't calculate c (except perhaps in a lab exercise as an undergraduate).
But gravity seems to propagate at light speed. I thought that the "leakage" just made it weaker, not faster (than the other forces).
No they aren't. Dimensions are degrees of freedom.
This is because the photons have to diffuse through the outer layers of the star while the neutrinos are unimpeded. The early arrivial of the neutrinos is exactly as predicted by supernova theory.
In other words, you think it may be an effect of general relativity. Unfortunately, those effects are well-understood and accounted for.
But there isn't enough room inside a politician's head for this sort of experiment (their egos, on the other hand, would easily suffice, if they weren't full of hot air).
> ...MINOS uses a matched near detector / far detector layout...
I didn't know that. Thank you. That means that if the time precision of MINOS can be improved (presumably much cheaper than building a detector at the LHC) the detector-detector experiment I suggested elsewhere can be done soon.
> they seem to randomly change from one kind to another.
Not randomly.
...is to run the experiment with neutrino detectors at both ends, thus eliminating many of the variables involved with comparing the phase of the proton pulse string at the transmitter with the phase of the muon pulse train at the receiver. I assume that such an experiment is being planned right now, unless there is some reason obvious to physicists but not to me that it would be useless. This would, of course, be very expensive: I can understand not rushing into construction of such a system until all other avenues have been explored.
Even (as seems likely) that the neutrinos turn out not be exceeding c, I think that we will learn something interesting from this. I doubt that the explanation is a simple oversight or math error.