Are not gravity waves believed to “bend light”. If so, can/do they also effect the speed of light?
In the very tiniest early fraction of the beginning of the “big bang”, isn’t it said that it was all energy and none of it had “cooled” into any form of matter, and if true was there then no gravity yet to speak of. And that’s true then could light have been - for some period of “time” - very much faster than it is today?
Or I am too ignorant and just asking a question learned physics would say is dumb.
Gravity bends space-time. Photons traversing that bent space-time will appear to have been affected by gravity by having their path changed, but that isn't how it works.
Light moves more slowly in a gravitational field (as predicted by Einstein). The bending of light then follows from the least time theorem of Heron of Alexandria - light always follows the path that gets it there quickest. But how does it know? I wish I had a least time theorem to get me around Singapore.