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A comment on The Last of the Universe’s Ordinary Matter Has Been Found. Parent comment

Re:The Last of the Universe’s Ordinary Matter Has Been Found by deathanatos on Monday September 10, 2018 @08:39PM (#17956300)
How can it be both finite in size, and have no edges?

To me, it would seem that were it finite, there would be a point at which one would look back, and see the galaxy and clusters that compose the universe; forward would be an expanse of nothingness. But if this isn't the case, then how I can keep progressing forward (presumably forever, as I can't hit an edge) through space, encountering galaxy after galaxy, but it is still finite?

Unless this is like RPG games where the edges wrap.

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Re:The Last of the Universe’s Ordinary Matter Has Been Found by mecameron on Monday September 10, 2018 @09:50PM (#17956622)
The surface of the Earth is finite in size and has no edges. You can keep progressing forward without hitting an edge.
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Re:The Last of the Universe’s Ordinary Matter Has Been Found by Neeek on Tuesday September 11, 2018 @02:39AM (#17957604)
There have been recent studies which show that universe is probably "flat" though.
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Re:The Last of the Universe’s Ordinary Matter Has Been Found by cygx on Tuesday September 11, 2018 @02:53AM (#17957656)
Or very slightly curved - measurements come with error bars, so we can't be sure if it's exactly flat. Also note that flatness and finite size are compatible in case of non-trivial topology (think of the flat torus - pacman world - which, however, is not isotropic).
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Re:The Last of the Universe’s Ordinary Matter Has Been Found by GW150914 on Monday September 10, 2018 @08:43PM (#17956323)
How can it be both finite in size, and have no edges?

Good question, but find me the edge of an idealized balloon. Where is the edge of a sphere? As to why you won’t come back, remember that spacetime is expanding faster an faster, and you can only travel below light speed. Mind you that’s just one possibility. The universe at large could be a lot of different things, but as humans were causally disconnected from anything beyond the shrinking observable universe. Shrinking from our perspective at least, because of the aforementioned expansion and speed limit.

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Re:The Last of the Universe’s Ordinary Matter Has Been Found by AnimalMuppet on Monday September 10, 2018 @08:43PM (#17956326)
It is exactly the case that the edges wrap (presuming that I understand correctly, of course).
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Re:The Last of the Universe’s Ordinary Matter Has Been Found by Neeek on Tuesday September 11, 2018 @02:42AM (#17957610)
It is a running theory that space time could be curved and wrap, or be more traditionally flat, or even be some kind of saddle that means it is still curved but never meets itself again like a sphere does. Recent studies point to it being flat though, if I remember correctly.
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