I'm writing a piece on the electron neutrino. There's plenty of excellent material out there, but I'm struggling to find anything definitive about their speed. There is for example evidence from SN1987A:
Approximately two to three hours before the visible light from SN 1987A reached Earth, a burst of neutrinos was observed at three separate neutrino observatories. This is likely due to neutrino emission, which occurs simultaneously with core collapse, but preceding the emission of visible light.
Some reports mention an earlier burst which preceded the visible light by 7.7 hours. There are no reports that I know about described any neutrino lag. There's also the infamous OPERA faster than light neutrinos incident of 2011:
In 2011, the OPERA experiment mistakenly observed neutrinos appearing to travel faster than light. Even before the mistake was discovered, the result was considered anomalous because speeds higher than that of light in a vacuum are generally thought to violate special relativity, a cornerstone of the modern understanding of physics for over a century.
I didn't have much of an issue with this myself, and would point out that they didn't measure neutrinos to be going slower than light. And yet one can find assertions that cosmic neutrinos slow down. But is there any evidence of this? Do we have any evidence of slower-than-light neutrinos?
Edit: my question is different to speed of neutrinos where the accepted answer is 6 years old, and says your question is equivalent to asking what the absolute mass of the neutrinos is. I'm definitely not asking that. I'm asking if we've ever seen a neutrino going slower than light. If the answer is no, because neutrinos can never go slower than light, this means that a neutrino is more like a photon than an electron. And that despite the claims associated with neutrino oscillation, that it doesn't have any mass at all.