3 ms·
Well, the point is that there was a neutrino burst coincident with SN87a. So if there was one 4yr earlier, too, then you'd have to explain how the same event pr
by lutorm 15y ago
Well, the point is that there was a neutrino burst coincident with SN87a. So if there was one 4yr earlier, too, then you'd have to explain how the same event produced two bursts of neutrinos with different speeds, while within the burst they apparently had exactly the same speed.
If neutrinos have mass, they can travel at any speed <c depending on their energy, like any other massive particle. Of course, the upper mass limit is quite low, so even with very little energy they will go very fast.
(Edit: In fact, the arrival interval of those neutrinos puts an upper limit on the neutrino mass, because the larger the mass, the more different the speed and the more dispersed the arrival of them at Earth.)
- nickolai 15y agoI'm no physicist, so I am just guessing. It could be some phenomenon similar to what we see in emission spectrums, where a pure source can emit photons at multiple precise energy levels. except that in the case of particles with mass(apparently neutrinos have a mass) this would result in a difference in speed. Not a big enough difference to be noticed on 700 km , but enough to make a 4 yr difference on 170kly. Of course this is still wild speculation without much background.
- lutorm 15y agoNeutrinos released in type II supernova explosions are thermal, so they should have a broad spectrum unless pretty much everything we think we know about SNe is wrong.
- kpanghmc 15y agoMaybe the neutrinos that appeared 3 hours before the event are from another event altogether (one that occurred even further away, whose light particles haven't even reached us yet)?
- lutorm 15y agoGiven that the flux goes as 1/r^2, and the sum total of the neutrinos detected in association with 87a was something like 17, a SN in any external galaxy would be undetectable.