# The Opera Neutrino Experiment and the Supernova 1987

So this probably stems from my massive ignorance about post-Newtonian physics but the supernova results of 1987 which measured neutrinos arriving 3 hours before the light from the supernova have been presented as a non-trivial objection to the Opera result.

However if the Opera result is confirmed, then doesn't that weaken the supernova objection since star mechanics relies heavily on relativity and such a result might imply that relativity is not the complete picture which in turn could imply different star mechanics than the one we understand?

Thanks

Edit: To clarify, I'm asking whether the supernova objection may not apply given that this experiment seems to challenge relativity which is what has been used to understand the behavior of stars, supernovae and such.

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I'm not an expert in stellar physics by any means, but I can say this: the velocity discrepancy observed by OPERA, $\frac{v - c}{c} = 2.9\times 10^{-5}$, would correspond to a delay ("prelay"?) of around 4 years for neutrinos coming from SN1987A. The observed delay was only 3 hours, which is smaller by a factor of roughly ten thousand. So if you assume that (1) the OPERA results are legit and (2) the SN1987A neutrinos travel at the same speed as the OPERA neutrinos, the required corrections to relativity would have to affect stellar models in such a way as to delay escaping photons by almost exactly the right amount of time to cancel out the speed difference at the distance between Earth and the supernova: 4 years, to a precision of $10^{-4}$. That'd be a pretty amazing coincidence. So it seems unlikely.

If you wanted to explain the OPERA results with a modification to relativity (as opposed to them just making a mistake), it seems almost certain that it would have to be some sort of energy-dependent or flavor-dependent effect to be consistent with the supernova. Neither possibility is particularly clean theoretically. (Well, that or the neutrinos we detected from SN1987A actually came from some other source, but again that would require a giant coincidence.)

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"The observed delay was only 3 hours, which is smaller by a factor of roughly ten thousand.". If the superluminal effect is real, and the most realistic model of superluminal particles are still the well-known tachyon kinematics, then the delay factor is a function of the $\gamma$ factor of the tachyon, which is a function of the energy-momenta –  lurscher Dec 2 '11 at 1:38

The OPERA results are consistent with SN 1987A measurements in case of ultra superluminal small initial jumps:

Instead of neutrinos travelling 730km with a speed slightly larger than c, it may be that they are created in a process which involves a step where some particle travels a distance of order ~10m with a speed many times larger than c, which gets averaged over the whole distance.

If neutrino production in SN 1987A also included such a superluminal jump, its effect would be negligible.

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This is the model they are pushing now, and this sort of thing requires a frame to define instantaneous. Do the neutrinos always jump in the same direction, regardless of the rotation of the Earth, in exactly the Earth's frame? That is absurd. The delay must depend on time of day, time of year, etc. It violates causality for short distances by more, so even a zero baseline experiment would see the effect. I agree that this type of nonsense is less conflicting with experiments than the previous type of nonsense, but OPERA is still obviously a systematic error, they aren't fooling anybody. –  Ron Maimon Dec 2 '11 at 4:21
@Ron: I mostly agree; however, aether dragging, the predominant theory of a medium of light in the 19th century, has been disproven by Michelson-Morley, Hammar and other related experiments, but they can't be easily repeated with neutrinos... –  Christoph Dec 2 '11 at 12:12
btw, I would be interested in a list of historical 'obvious systematic errors' which were later explained by new physics... –  Christoph Dec 2 '11 at 12:14
The list would be short: cosmic microwave background, too few solar neutrinos, Pd/d cold fusion. All of these involved more efforts to reduce the systematic errors and check the model than has been displayed by OPERA. If they would just publish their exact GPS position/timing system, the error would be found in a few days. –  Ron Maimon Dec 2 '11 at 18:42