Greetings. I thought about how/ why light propagates slower trough matter than vacuum. Generally it is excepted that it happens because photons are absorbed and then emitted by the atoms and it kinda makes sense. But I see other possibilities. I propose and experiment: How about shining photons trough a dense beam of neutrionos - the stuff that only interacts with gravity [and strong.. or week nuclear force?] - if the beam is slowed down [and the angle is changed] then there would have to be another explanation for why light slows down, wouldn't there? A possible alternative could be, for example, that gravity on the really small scale doesnt follow the inverse square law and gets way stronger - curving the space much more and, like all gravity does, creating a region of .. well.. "larger on the inside", which means more time for light to pass trough.