I only did high school physics and I don't remember much about that so I might not have my facts straight.
I was watching a documentary about the Big Bang and it said the expansion of the universe is known because of measuring the doppler shift in light.
So that would mean that the objects emitting the light, stars for example, are moving away from us.
The Universe is defined as everything.
So if we are in the universe, aren't we also expanding as well?
If we are also expanding shouldn't the distance that the light travels through remain in the same proportion to us and the light emitting object, and therefore there should be no doppler shift?
If the distant star is moving away from us and increasing the distance between it and us then we aren't expanding at all.
And so if it is only the boundary of the Universe that is expanding, and not the matter within it, what is it expanding into?
I probably have simplified one of these concepts too much. If anyone knows a solution to this problem I'd appreciate the relief from scratching my head about this.