I’d been wondering about this

The MAGIC gamma-ray telescope team has just released an eye-popping preprint (following up earlier work) describing a search for an observational hint of quantum gravity. What they’ve seen is that higher-energy gamma rays from an extragalactic flare arrive later than lower-energy ones. Is this because they travel through space a little bit slower, contrary to one of the postulates underlying Einstein’s special theory of relativity — namely, that radiation travels through the vacuum at the same speed no matter what?

Scientific American

Maybe Einstein’s theories are like “his” videos. They “were never designed to make [us] smarter, only happier.”