reply to post by Idonthaveabeard
Most people think the universe is infinite. Nobody is sure, but if we are indeed talking about an infinite universe, then there is no center and there
is no edge and there is no wall. It just goes on and on and on.
And a common misconception is that when people say space expands, most of us would obviously think that it expands at the edge right? That if you
measured it from edge to edge, the edges would be farther apart tomorrow right?
But an infinite universe has no edge. It's not the boundaries getting farther apart. There are no boundaries. It doesn't expand out into anything.
No matter how far you go you would never reach an edge or find anything on another side. There is no side to reach. So, it has to expand within
The answer is it expands between the planets and galaxies and any other cosmic object that isn't gravitationally bound together. For example our
solar system, the gravity of the sun holds it together. And our galaxy, a black hole or something at the center holds it all together. Also, the atoms
in our planet keep it gravitationally bound so that when space expands, the planet doesn't get all stretched out and so on. So everything stays
pretty much the same distance from each other.
But if you take two objects in space that aren't gravitationally bound to each other, then the space between them expands and the distance between
the two objects literally grows larger.
And it is the space expanding. It is not the two objects moving away from each other. For example if there were three planets lined up and you moved
the middle one away from one planet it would have to get closer to the other planet. But that's not what happens. All three planets stay in the same
spot, but the distance between all three gets larger. It's literally the empty space between that's getting stretched.
However, there may be some other trick going on, but that's pretty much what appears to be happening and what they say when space expands. They
literally mean that the nothing, the empty space between things, is getting bigger. You could say, well the universe isn't expanding. It's just all
the objects in the universe are moving away from each other. But when you do the math that way it gets all messed up.
Because not only are the galaxies moving away from each other, the rate at which they're moving is SPEEDING UP and they're moving too fast! Galaxies
have a lot of mass. There's no force in the universe that can just speed up two galaxies so they keep getting father apart. Something else must be
Also, the observable universe. It's too far apart! The universe is 13 billion years old, but we know of things that are some 40 or 50 billion light
years apart from each other. And that's just what we know about. There may be galaxies trillions of light years away from us.
How is that possible? Even traveling at light speed, if two galaxies originated at the big bang, then the farthest apart they could be is around 26
billion light years. How'd they move so fast? The answer is obviously they didn't. The distance between them got larger and since empty space has no
mass, it could do so at a rate much faster than light speed. Especially right after the big bang. And when it did, it stretched everything else out
right along with it.
And that's why many people think that is what's happening. But how does nothing get bigger? That's the real question.
Basically what it boils down to is this. They used to think the universe was static and unchanging and it had just always been there. Then they
discovered the big bang. And they realized that if that's the case, there's no way the universe could be that big yet. It was only 13 billion years
old. So how did everything get so far away? Why is it speeding up? Oh I know! Empty space expands!
So, you can either think, hey they were wrong and there was no big bang and they just made this crap up to fit their equations, or that nothing
somehow gets bigger. Strangely, when tested in experiments. It appears that nothing really does get bigger and stuff gets farther apart without
moving. So weird.