# Infinite universe? **URL:** \ **Category:** Great Debates\ **Created:** [January 3, 2026, 5:54am UTC](https://boards.straightdope.com/t/infinite-universe/1026295 "2026-01-03T05:54:35Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 3, 2026, 5:15pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/61 "2026-01-03T17:15:39Z")
> [@Whack-a-Mole](#): > > Even if we assume any atom is as likely to connect with any other atom (which they don’t) there is a finite number of arrangements of those 10^80 atoms. After that things will start to repeat. If we have infinite time the repeats have to happen. While the argument does work with infinite space, it doesn’t work with infinite time. If, as seems likely, the Universe will keep expanding forever, then the average distance between atoms will also increase, and thus the probability of interactions between atoms asymptotically approaches zero. Take any finite volume of space and any finite arrangement of matter in that space, and the number of times that arrangement would be expected to occur in that volume would converge to some finite number. And for macroscopic objects and volumes smaller than the current observable Universe, it would converge to a number much less than 1 (i.e., even given infinite time, most arrangements of matter would never occur at all, and even those arrangements that do occur would most likely never occur again). ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [January 3, 2026, 6:00pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/62 "2026-01-03T18:00:23Z")
> [@EllisDee](#): > > Interestingly, it appears that quantum computers have recently managed to generate true random numbers. That was a little bit badly reported. The interesting thing here isn’t that a quantum computer produced a truly random number (that’s a trivial task, in fact, commercial random number generators where one of the first products spun off from quantum information science—although really, they were just glorified beam splitters), what was interesting was that they managed to produce a random number in a _certified_ way, i.e. one that can’t be spoofed by classical resources (up to some plausible complexity conjectures). The thing is that quantum computers can solve certain problems that are hard for classical computers, but _only_ by sampling randomly from the answer distribution. So if you can certify that the quantum computer has indeed solved that problem—which in the protocol needs a lot of classical computation, because the problem isn’t of the ‘easy to verify’ sort that get most press for quantum computing—then you also know that there is a certain amount of randomness to the answer, which you can then extract (by classical computation). Thus, you know that the number you’ve obtained is truly random, and hence, usable for certain cryptographic tasks. As for infinity, well, the randomness in quantum mechanics comes through the selection of one particular outcome out of a range of possible outcomes. There are no finitary means by which one could effect this selection; and indeed, it [has been proposed](https://plato.stanford.edu/archives/fall2022/entries/spacetime-supertasks/#QuanMechSupe) that it could be solved by a so-called _supertask_, i.e. a task utilizing infinite resources. But I think saying anything more than that would be to overinterpret the current state of knowledge. > [@EllisDee](#): > > I think the explanation I’m looking for is probably here, but I can’t quite wrap my head around “the Hubble sphere depends on spacetime (if flat) being infinite.” This seems like of restating of the premise that if the universe is flat it must be infinite. Well, it’s only the case that every point in spacetime is surrounded by a Hubble sphere (such that beyond it, everything recedes faster than light) if for each point, there’s a set of points around it such that each of those is sufficiently far away to recede fast enough. But this leads to an infinite spacetime: pick a point, pick a direction, go to a point on the Hubble sphere for that point; continue in that same direction, keep doing that, and either, you can do that forever—and spacetime is infinite—or you’ll hit a point ‘close’ to the boundary where there are no points in that direction that are far enough away. So I don’t think a boundary can recede faster than _c_ from _every_ point in spacetime (at least not due to Hubble expansion), meaning there are some points from which the boundary would be reachable. > [@Mijin](#): > > “Equivalent to” would need to do a lot of work here. It’s precise in the sense of computational equivalence: what you can compute with a computer capable of traversing infinitely many steps, you can compute with an ordinary computer plus a suitable random number (meaning, for every function computable by the first device there exists an algorithm for the second and an algorithmically random number such that it can be used as an oracle for the computation). ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 6:02pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/63 "2026-01-03T18:02:25Z")
> [@Whack-a-Mole](#): > > Where does the “flip” or change happen from random to the order we all experience? Right. That’s the fundemental question of quantum mechanics. The Copenhagen Interpretation says “shut up and calculate”, but there’s something very unsatisfying about that to an inquiring human mind…? ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [January 3, 2026, 6:19pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/64 "2026-01-03T18:19:54Z")
Is space infinite in extent? I know we have the universe we can observe but is there infinite space beyond what we can observe? If so, what does that mean for the expansion of space? Infinite space (already) is expanding into infinite space? ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 6:21pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/65 "2026-01-03T18:21:48Z")
> [@Whack-a-Mole](#): > > Or, if infinite space, there are infinite “you” out there because those 118 elements in the 10^80 atoms can only be put together so many ways and in an infinite sequence it is likely the “you” sequence repeats. I don’t think you have quite grasped the subtlty and _weirdness_ of Godel’s ideas yet. You are still thinking within the intuitive idea of ‘what could be bigger than infinity?’ There again, Godel ended his life as a mental patient… maybe there are ‘Some Things Man Was Not Meant to Know’… ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [January 3, 2026, 6:24pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/66 "2026-01-03T18:24:35Z")
> [@EllisDee](#): > > This assertion caught me off guard, as I’ve never heard that the universe is infinite until quite recently. Nobody has addressed this, and I was puzzled because I know I’ve heard the infinite universe mentioned for a long time. Brian Greene, a physicist who writes bestselling popular science books about the universe, mentions the possibility of a an infinite universe in his 2004 _The Fabric of the Universe_ and expands on the topic in his 2011 _The Hidden Reality_. In the latter he says directly: “this means that conditions in the infinity of far-flung patches [in a flat universe] - regions of space like the one we inhabit but distributed through a limitless cosmos - _necessarily repeat_.” [italics in original. That book describes nine distinct types of multiverses. This one is called the “Quilted Multiverse”. Others have expanded on the idea. Here’s [a very short, basic article](https://societyofmodernastronomy.wordpress.com/2014/10/12/the-patchwork-multiverse/) that makes the same points. Admittedly, Grene doesn’t say that the model is most commonly used or that our particular universe is replicated, let alone infinite times. What Greene and the others I’ve read do say is that it cannot be dismissed as a possibility because we don’t know enough yet. Examining the ramifications of the various universes and multiverses is the most common in popular science, IMO. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 3, 2026, 6:36pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/67 "2026-01-03T18:36:00Z")
> [@Whack-a-Mole](#): > > Is space infinite in extent? I know we have the universe we can observe but is there infinite space beyond what we can observe? If so, what does that mean for the expansion of space? Infinite space (already) is expanding into infinite space? The first questions, I’ve already answered: We don’t actually know, but out of all of the possibilities consistent with what we observe, it seems to be simplest. And yes, infinite space is expanding into infinite space. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [January 3, 2026, 6:39pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/68 "2026-01-03T18:39:43Z")
> [@Chronos](#): > > And yes, infinite space is expanding into infinite space. So…why isn’t what you posted (below) already the case? We are in infinite space now. How does “more infinite” change the math? (is this back to Cantor?..your infinity is bigger than my infinity?) > [@Chronos](#): > > Take any finite volume of space and any finite arrangement of matter in that space, and the number of times that arrangement would be expected to occur in that volume would converge to some finite number. And for macroscopic objects and volumes smaller than the current observable Universe, it would converge to a number much less than 1 (i.e., even given infinite time, most arrangements of matter would never occur at all, and even those arrangements that do occur would most likely never occur again). ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [January 3, 2026, 6:47pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/69 "2026-01-03T18:47:07Z")
> [@Half\_Man\_Half\_Wit](#): > > It’s precise in the sense of computational equivalence: what you can compute with a computer capable of traversing infinitely many steps, you can compute with an ordinary computer plus a suitable random number But again we have no reason to think any computation is happening, so this equivalence is irrelevant to making an empirical claim. I may as well say pixies can make randomness with their magic dust, so something equivalent to _that_ must be happening. ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 6:51pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/70 "2026-01-03T18:51:43Z")
> [@Chronos](#): > > And yes, infinite space is expanding into infinite space. I’m not sure that’s language a professional cosmologist would use. There isn’t any ’space’ _outside_ the universe. Space (and time, or space/time, as Minkowski put it) are intrinsic properties of the universe itself? ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 6:58pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/71 "2026-01-03T18:58:25Z")
> [@Mijin](#): > > But again we have no reason to think any computation is happening Just wait till I crack the root password and break out of the sandbox! **THEN** you’ll see something. ha ha! ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [January 3, 2026, 7:09pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/72 "2026-01-03T19:09:40Z")
“ Ludwig Boltzmann, who spent much of his life studying Statistical Mechanics, died in 1906, by his own hand. Paul Ehrenfest, carrying on the work, died similarly in 1933. Now it is our turn to study Statistical Mechanics. Perhaps it will be wise to approach the subject cautiously.” ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 7:19pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/73 "2026-01-03T19:19:44Z")
> [@Andy\_L](#): > > Perhaps it will be wise to approach the subject cautiously.” I’m pretty safe, I think. At my age I don’t have the real math power anymore to go deep. (Like Peter Higgs, who was finally validated after decades) As Fred Pohl said, though: science is the best spectator sport in the universe! ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [January 3, 2026, 7:29pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/74 "2026-01-03T19:29:44Z")
I do not see that there are any _mathematical_ problems (though we may explore these issues, if any)— the question was whether there were some sort of contradiction between the “model most commonly used by modern cosmology” with its infinite, flat universe and there being a super-dense “Big Bang”, and the answer, as points out @Half_Man_Half_Wit , is no. Not that an ultimate model of cosmology, or high-energy physics for that matter, is known yet. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [January 3, 2026, 7:29pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/75 "2026-01-03T19:29:58Z")
Have you read Pohl’s book on the subject? (“Chasing Science”?) ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 7:37pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/76 "2026-01-03T19:37:10Z")
> [@DPRK](#): > > I do not see that there are any _mathematical_ problems In a way, though, there sort of are? Some versions of string theory seem to lead to a prediction of 10^500 possible universes. Whether this has any ‘real’ significance for physics is an open question? ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 7:38pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/77 "2026-01-03T19:38:34Z")
> [@Andy\_L](#): > > Have you read Pohl’s book on the subject? (“Chasing Science”?) No, I just heard the quote. Sounds interesting; I’ll chase it down, thanks! ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [January 3, 2026, 8:02pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/78 "2026-01-03T20:02:17Z")
That is not what is meant by the current “standard model of cosmology”. If one introduces string theory, the geometry of the universe (multiverse) is certainly going to look more complicated. Certainly, string theory is going to lead to interesting problems in mathematics and theoretical physics to explore, e.g. mirror symmetry and what not. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 3, 2026, 8:05pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/79 "2026-01-03T20:05:41Z")
> [@Whack-a-Mole](#): > > So…why isn’t what you posted (below) already the case? We are in infinite space now. How does “more infinite” change the math? (is this back to Cantor?..your infinity is bigger than my infinity?) To be clear, if space is infinite, then infinite space is expanding into infinite space. > [@xtenkfarpl](#): > > I’m not sure that’s language a professional cosmologist would use. > > There isn’t any ’space’ _outside_ the universe. Space (and time, or space/time, as Minkowski put it) are intrinsic properties of the universe itself? It’s not the way I wold have phrased it myself, but it was the way that the questioner put it. ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [January 3, 2026, 8:19pm UTC](https://boards.straightdope.com/t/infinite-universe/1026295/80 "2026-01-03T20:19:37Z")
> [@DPRK](#): > > That is not what is meant by the current “standard model of cosmology”. If one introduces string theory, the geometry of the universe (multiverse) is certainly going to look more complicated. Certainly, string theory is going to lead to interesting problems in mathematics and theoretical physics to explore, e.g. mirror symmetry and what not. But the question is, are we asking in the right way? A child might say a rainbow exists because it is made of butterfly wings. Lies to children, as the saying goes. It _almost_ has some truth: diffraction and refractive index are involved, We have to build understanding: you can’t start learning calculus until you have some basis in arithmetic. [Previous page](https://boards.straightdope.com/t/infinite-universe/1026295.md?page=3) [Next page](https://boards.straightdope.com/t/infinite-universe/1026295.md?page=5)