If it hadn’t been proved, why would it be called a theorem?
But your Wikipedia cite says
You could have led with that and skipped the “hunh?”
Just my $0.02
Missed edit window:
Also, is proof that the math is rigorous and checks out the same as proof that recurrences happen? (that was where my brain was when I made that comment)
You seem to be thinking about the universe as an expanding ball. But that is not the case. It is expanding everywhere. There is no centre, there is no single place you can point to and say that is where the nucleus of the Big Bang is. The Big Bang happened everywhere and if the universe is infinite then it has always been.
To me a finite universe seems less plausible because for it to be finite it would have to curl in on itself such that if you go far enough in one direction you would come back to the same place.
To be fair though, thinking about it as either finite or infinite, both options are fairly mind blowing.
This is true but also you can say the center of the universe is your head. Also mine and anyone else.
To each of us, our observable universe is slightly shifted from everyone else.
So, from your perspective, you are the center of the universe. 
An infinite Universe is actually generally considered the simplest possibility. Is it true? We don’t, and can’t, know. But it’s certainly plausible.
That depends on the Universe also not expanding. Lots of luck finding a cosmological model that lasts long enough without any expansion.
At Broadway and 21st, we see a geometry that makes sense to us and is repeatably consistent. Down around the scale of the innards of the thing that is running this here device on which I am reading this here site, it appears that the kind of geometries we use are very similar to the eyesight ones. Go some bit finer, though, and your confidence in stuff will probably start to get shaky. Down around the Planck length, I and going to guess that there is a lot that does not make sense.
Out there, past Pluto, past Andromeda, past the Virgo Supercluster, geometries that we can observe appear to be consistent with our front-yards. However, we cannot make those observations except by framing them in an accessible context: there might be aspects to mondo-reality that we are not aware of because we lack a vocabulary that can reference those things.
We live in a little box composed of what we can taste and what we can guess about it. A hall-of-mirrors multiverse may reality, but I strongly suspect that there are just too many naïve flaws in the model.
It is also possible that there are an infinite number of universes where monkeys fly out of my butt.
Whack-a-Mole, Saffer, Chronos, eschereal: Very helpful. Thank you.
Guilty as charged. But bear with me. If the universe was an expanding ball following the big bang, and the universe has a radius 1000 times that of the visible universe, then in all probability (> > 99%) a random observation point in the greater universe will perceive constant expansion in every direction. Because the visible universe won’t overlap with the greater universe’s edge. What empirical data (or logical inference) conflicts with this model?
Not saying this model is true. eschereal’s point is familiar and well taken. There’s no compelling reason that eg Euclidean geometry will work best 20 orders of magnitude away from the familiar in either direction. Heck GPS deviates from Euclidean.
(ETA: ~100 trillion kilometers is only 10 light years (I think), so maybe I should say 30 or 40 orders of magnitude.)
If you have an “infinite number” (whatever that means) of monkeys banging at typewriters, one will not type out the complete works of William Shakespeare – an infinite number of them will. Similarly, an infinite number will not. But, the distance between the monkeys producing gibberish (or broken typewriters) and those typing out literary classics is both infinitely large and infinitely small, so the chance of locating the Shakespearean monkey amounts to both impossible and inevitable at the same time.
Research continues.
It’s kind of like the somewhat absurd sounding concept of “infinite nothingness”. Let’s say for arguments sake that matter ends at or someplace beyond the horizon of the observable universe 45 billion light years away. Is the concept of “forever” in a black empty space with no light, energy. or matter in it even meaningful in any way we can comprehend?
I suppose theoretically if space and matter did go on for infinity, you would find every possible combination of every possible Earth somewhere out there. And theoretically if you could locate exactly what you are looking for and create a wormhole to travel there, you could pretty much visit any time or alternate variations of time in Earth’s past, present, or future. They would be copies that would have no ability to influence each other. But you wouldn’t have to worry about messing stuff like paradoxes or killing your grandfather or feeling obligated to kill Hitler or anything like that. But you also couldn’t go back and invent Google either.
Doesn’t seem as fun as conventional time travel fiction though.
There is a symbiosis between space and stuff. Stuff (matter and energy) must have space in which to exist, but space is not known to exist without having at least some stuff in it: stuff and space create each other. Similarly, time and events rely on each other: if there are no events, time is a non-meaningful metric.
Hence, if a boundary to the physical universe exists, there is literally nothing beyond it. No space, because no particles have gotten far enough to impel the existence of a place to be, and no time passing because nothing is happening.
Could there be other universe bubbles beyond the boundary? No, not really, because there is nothing out there. It is not a location because there is no space or time beyond the boundary.
With all due respect, this is on about the same level as dorm-room pot-induced musings.
I was born stoned. I think my mother must have been a Tim Leary acolyte.
Well, there’s the idea that our universe may be within a black hole, which is in another universe within another black hole, and infinitely nested within each other so on and so on. I kind of like it. PBS Space Time did a nice video on it about a year ago. Their conclusion was basically probably not, but we can’t rule it out.
Including Earth-5 minus minutes ago. An infinite number of E-5min have the same constellations that we have. And an infinite number don’t.
I am (almost) certain I have heard the likes of Neil DeGrasse Tyson talk to cosmologists that there probably are other bubble universes.
I think I found it here (link below) where Tyson speaks to Paul J. Steinhardt, Albert Einstein Professor in Science, Director of the Princeton Center for Theoretical Science at Princeton University.
I get that asking anyone on a message board to listen to a 55 minute podcast is a big ask and not fair but I am not sure I can summarize it (although the relevant bit is in the first 20 minutes…better but still a lot).
Trouble is, talking about bubble universes out there somehow is not a lot better than “here be dragons”. It makes for good press and some science popularists might justify these things as ways of engaging popular culture, but it is little short of just making stuff up.