Question

How far does a neutrino travel in a second?

Answer 1

Ideally a neutrino with zero mass would have to move at the speed of light, but as mass increases speed should decrease. To my knowledge, it is still undecided whether or not the mass of the neutrino has a great enough affect on it to slow the particle down. However, at this moment in time, all three types of neutrinos are believed to travel at the speed of light or close to it when you factor in confidence intervals of data points. So to answer your question simply 2.998 x 10^8 m/s.

Answer 2

Objects with zero mass only ever travel at the speed of light. But experiments have shown that neutrinos have a very small non-zero mass, though the value of this mass has yet to be determined (we only have an upper limit of it). However, typically most neutrinos travel very close to the speed of light, which means that we can approximate the distance that they travel in a second by taking the upper limit of their speed as being that of light, or 299,792,458 m/s. Therefore a neutrino would travel close to 299,792,458 metres in one second, but the precise value would depend up how close it is to the speed of light, which can vary.

Answer 3

I was told of the following observation: We now have neutrino detectors. For a recently-observed supernova, we were able to detect and time the arrival of the photon burst and the neutrino burst. Great ... should be able to get an idea of the neutrino speed, once supernova distance is estimated. But ... a problem ... the neutrino burst arrived before the photon burst! Hypothesis: photons were slowed down by interstellar dust, and neutrinos had less interaction with dust, so were not slowed down (as much). This anecdote told to me last year by my physics prof. Have not gone looking for papers.

Any further info on that anecdote?

Ken R.

Answer 4

It depends how fast it's going! But usually they tend to go at very nearly the speed of light because if you give them even the tiniest nudge they're off to the races.