"Theory" of space-time which posits anything like a "center" which is located somewhere within, again, our 4 dimensional spacetime itself.

Now, extrapolating the old "flatland sphere" idea, if spacetime were curved - and closed- in such a way that the universe was a sphere in a higher mathematical dimension, then yes there would be a "center" which nevertheless existed in a higher mathematical dimension outside of our spacetime, much as the core of the earth is nowhere on its surface--

But that said, observational analyses to date have all indicated that spacetime is neither curved in on itself (spherical) NOR outward (saddle-shaped) but rather, "flat" at largest scales, albeit again in 4 dimensions.

Also if one steps outside of "time" (as much as is mentally possible) and accepts current big bang/hyperinflation theory, it is possible I suppose to argue that a "center" (if not "the" center) sits at the big bang, both in space and time- but the big bang occurred everywhere, so again, if you're talking now the center is, like the leftover 3 degree echo of the big bang, everywhere.



Positing a "center" somewhere in our own, current spacetime as it stands now, runs into all sorts of logical problems, not the least of which is that it implies an "edge" or boundary, and then what's beyond that?

(one of the appealing factors of the spacetime-curved-into-a-higher-dimension-sphere idea is, of course, that it avoids that problem by saying if you go far enough in one direction, you end up coming back from the other way, sort of like flying off the right side of the screen in Asteroids and coming back in in the left.



But unfortunately, again, observations don't seem to indicate that one is true)

Personally, my own leanings are towards something like the infinite self-propagating eternal inflationary theory of Guth and Linde (of which our own Universe would be a tiny bubble), and I believe everything is mind-bendingly infinite in all directions and across all scales, not just multiverses but an infinite number of multiverses and beyond that types of multiverses, and so on. And as mathematicians know, asking what the "center" of infinity (much less infinite infinities) is, is a meaningless question.


...also, adding a brief detour out of science and math and into philosophy- as the solipsism jokes upthread allude to, from a purely experiential/zen/existential standpoint for me, the universe DOES have a center, and yes, I'm sitting at it right now. Meaning, as much as my own experience is concerned, from the moment I first became conscious, everything that has ever taken place, from my perspective, has happened with me smack dab at the center. Wow! I must be important! Or something. I don't say this because I have a huge ego (although I do) but rather because If I'm being rigorous from an experiential viewpoint, well, the ONLY experiential viewpoint I have or will ever have, as far as I know, is mine. The only vote that matters, so to speak.

And as such the whole fuckin' shebang revolves around (or to some extent, takes place inside) my own head. So as for a "center", there's that, I guess.