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Comment by Keegs | Hacker News Reader

This is my favorite possibility, that space has a “finite volume but no edges: if you travel farther than the scale of the universe, you end up back where you started.” It’s comforting on an existential level to imagine the amount of stuff around us is finite.

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So how would you explain the fact the galaxies are moving away from each other with an ever increasing speed in this kind of shape?

Edit: To answer it myself: https://www.quora.com/What-are-the-implications-of-the-three...

“ The torus moves into itself and comes out at the other end, where the locations of ‘coming out’ could be what is driving what we observe as the expansion of the universe.”

The donut is getting bigger (but is still finite)

It's also possible particles increase causing expansion, this is just theoretical still. But if that's true, then it is finite but perpetually increasing. Potentially infinitely.

Bigger relative to what?

Relative to what it was before. It has an intrinsic size. Think of it in terms of matter density if you find it more comfortable. The density simply goes down over time; distandes between galaxies increase.

Density has the same issue. Density can only be measured against a baseline established outside of the medium being measured.

Just because you can't measure something directly doesn't mean it doesn't exist. There's plenty of things we only know only through indirect measurement.

Intrinsic expansion. Distances between objects in space grow.

That's what metric expansion of the universe is. Distances grow at speeds that are proportional to their distance from the observer.

Any closed curve does this. And if that's your only information, the simplest encoding for it is a sphere, not a doughnut.

This would also be the case on a hypersphere, which would also satisfy the cosmological principle. A torus is not isotropic.

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