[classicman]

Measurements of arrival times of photons and neutrinos from supernova SN1987a in 1987 provided a much better agreement with the speed of light, but those neutrinos were of a much lower energy. The possibility remains that velocity depends on energy.

Somewhat less rigid explanations include neutrinos taking “shortcuts” through extra dimensions. Undoubtedly, many more possible explanations will arise if all conventional sources of error are excluded.

The much more likely scenario is that the analysis has overlooked some seemingly insignificant but critical aspect, and that re-analysis will led to a very good agreement with the speed of light.

Fascinating nonetheless