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The universe MUST be infinite. What would you expect at the 'end' if it were finite, a random wall that has a signboard that says ' STOP! End of the universe. Employees only. Please maintain silence as our workers expand the premises so that you have more admittance area'? Actually, you are correct. The distances scientists know are slightly less than what they really are since the universe is expanding. Anything past the last few molecules of matter at the 'end' of the universe will be black and empty space. That emptiness will soon be filled up by the expanding universe. The atom that started the Big Bang was in this empty space.
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You cover a lot of ground here so I'm not sure what you are asking.
Yes, a civilization 1 billion light years away would see a universe laid out differently than ours, as in such and such galaxy over there and, oh look, there is the Milky Way 1 billion LY over there, but I really don't see what difference these logistics would make. They would also see the universe in the same physical (as in physics) and mathematical way we do, because these things are (supposedly) constant.
I'm not sure yours isn't a problem of semantics. The "observable" universe is finite... 13.7 billion LY according to you. BUT the "universe" is infinite, for our purposes here, because you cannot observe it.
Interesting, and yes, mind boggling.
Yes, a civilization 1 billion light years away would see a universe laid out differently than ours, as in such and such galaxy over there and, oh look, there is the Milky Way 1 billion LY over there, but I really don't see what difference these logistics would make. They would also see the universe in the same physical (as in physics) and mathematical way we do, because these things are (supposedly) constant.
I'm not sure yours isn't a problem of semantics. The "observable" universe is finite... 13.7 billion LY according to you. BUT the "universe" is infinite, for our purposes here, because you cannot observe it.
Interesting, and yes, mind boggling.
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The observable universe is what we can see. The universe generally speaking includes what we can see and what may be out there that we can see. Based on the rate of expansion we can figure how old the universe is. Kind of like rewinding a tape. If we know how fast the tape plays at and we know how far it is the center, we can figure out how long the tape has been playing.
Many of the galaxies we see may very well still be there and probably are. There are literally trillions of galaxies we can see. Yes the light left them billions of years ago but our galaxy's been here billions of years too and new stars are constantly being made so many of those galaxies are still there while others have collided into nearby galaxies and formed new ones. We're due to collide with the Andromeda galaxy in about 5 billion years.
We don't know the universe is infinite or not. It may very well be that it is round and if you go far enough you'll come back where you started, but we simply have no way of knowing. It may very well be infinite. There may be multiple universes in a multiverse. What was there before the universe, what "space" is it expanding into. We really don't know and I don't see how we ever will know. It's huge though; that we do know. Clusters of galaxies within larger clusters of clusters, all forming long bands of galaxies that kind of looks like an enormous grid. Mind boggling stuff.
Edit: Almost forgot. Yes, the galaxies are farther than we see them, but we know the rate of expansion so we can use that to calculate how far they actually are today.
Many of the galaxies we see may very well still be there and probably are. There are literally trillions of galaxies we can see. Yes the light left them billions of years ago but our galaxy's been here billions of years too and new stars are constantly being made so many of those galaxies are still there while others have collided into nearby galaxies and formed new ones. We're due to collide with the Andromeda galaxy in about 5 billion years.
We don't know the universe is infinite or not. It may very well be that it is round and if you go far enough you'll come back where you started, but we simply have no way of knowing. It may very well be infinite. There may be multiple universes in a multiverse. What was there before the universe, what "space" is it expanding into. We really don't know and I don't see how we ever will know. It's huge though; that we do know. Clusters of galaxies within larger clusters of clusters, all forming long bands of galaxies that kind of looks like an enormous grid. Mind boggling stuff.
Edit: Almost forgot. Yes, the galaxies are farther than we see them, but we know the rate of expansion so we can use that to calculate how far they actually are today.