I'm curious about what the are current models to explain the expansion of the universe I have a few hypothesis of my own but I wouldn't be an expert in astrophysics so I cant say if my views would compare much in this field.
I'm a little confused about the way we know the universe is expanding, the evidence behind the reasoning mainly,like for example I've read we know the universe is expanding due to its effect on light waves it stretches them so they red shift the same way something moving away from us would and this is happening in all directions, but is this the only explanation for these findings how do we know light doesn't just lose energy as it passes through space or the gravity well of our galaxy doesn't pull and stretch out the light to red shift it. Are there other ways light is known to stretch.
My hypothesis are mainly questioning whether the universe itself is actually expanding or if its just one conclusion of many given the evidence. But I'd like to be corrected on any of these, have something explained I'm not considering or talk more about research that has been done or is being done to explain the expansion.
If anyone could link somewhere I could learn more, comment of an existing theory or has a hypothesis of their own I'd be grateful