Quote:
Originally Posted by herr_oberst
This is why I chose lithography instead of physics and chemistry.
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This is why I chose astrophysics instead of lithography, chemistry and physics.
I'm not going to get into the semantic mishmash about forces, but I'll go back to the original question.
There is not a "center" on the Universe, which things are expanding away from. I know that's a bit non-intuitive at first, but think of this...
Imaging a large rubber band. Maybe, 10 miles across? Now, put a few ants on the rubber band. Each can see other ants along the band, maybe they can see how far other ants are because there's pen marks al around the band. So, ants have some sense of space, and distance.
Now, you, as a malevolent god, pull on the rubber band, stretching it. EVERY ant will see EVERY other ant moving away from them. Naturally, EVERY ant will look at that and say "if every single other ant is moving away from me, I must have some special place in the Universe, the center of expansion!". However, every single ant can say that, and therefore, they do NOT have any special place, by definition. The problem comes from the fact that the rubber band is a 1 dimensional world expanding in the second dimension, and that makes it SEEM like every single ant is at the center of expansion. In fact, none are, and the rubber band Universe is far more complex than the ants think it is.
We are in a 3 dimensional Universe which is expanding in the 4th dimension. Every single spec of dust in our Universe sees everything moving away from it, and therefore makes the logical mistake that they are at the center of expansion, which is false.
So, no center of expansion of the Universe, therefore, no point at the center where gravity goes to zero simply because of being at the center.