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So I can look through a telescope and spot one of the most distant galaxies from us around 14 billion light years away. Then an observer in that galaxy could be doing the same as me but looking in the exact opposite direction to my galaxy, and they would also spot a distant galaxy around 14 billion light years away (one that I can not see at all). And there could be an observer in this 3rd galaxy doing the same, but looking at a galaxy in the opposite direction (that neither me or observer 2 can see).... and so on, and so on.
So how many times can this repeat? I read somewhere that the universe might be closed or finite in size, and that we are analogous to 2D people living on a 3D sphere, so how many times can the scenario above repeat until you reach an observer who spots our Milky Way from the other side? Or does this just repeat infinitely? And how do/did we figure this out?
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We figure this out by taking accurate measurements of the curvature of spacetime with large interferometers in space. We just need to build them first.
All current data suggests the universe is flat and therefore infinite.
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>>7753187
>All current data suggests the universe is flat and therefore infinite
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>>7753187
Does this mean theories about other universes existing outside our own are essentially dead?
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>>7753187
If the universe is infinite, how did it go from being a singularity to being infinite?
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>>7753187
>measure the curvature of Earth with a ruler
>Earth is flat
I'm sorry it is still entirely possible that the universe is so big that our instruments can't measure a curvature that small.
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>>7753218
No, why should it?
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>>7753218
Those aren't theories, they are hypotheses. And no, it doesn't affect them.
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>>7753187
What about it being a four dimensional hypersphere? That would make it infinite in the sense that you would never reach an end but would keep passing the same galaxies over and over.
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>>7753323
The ruler used is the acoustic scale in the CMB. You will never build an instrument larger. it is possible the universe is just slightly open or closed, the current measurements place lower limits on the size of the universe.
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>>7753465
No, that would make it finite but unbound. Such a curvature is called closed in cosmology but so far the universe appears flat and not closed.
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>>7753306
When we say big bang. We mean BIG
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