# Multiple universes, infinite universe, and probablity **URL:** \ **Category:** Factual Questions\ **Created:** [May 25, 2014, 1:38am UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219 "2014-05-25T01:38:22Z")\ **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:** [May 26, 2014, 8:38pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/61 "2014-05-26T20:38:10Z")
All your argument says is that, if there is an infinitude of universes (or “branes”, or “worlds”, or whatever), then classical communication between them is impossible. Which is in fact one of the necessary premises of the Many Worlds interpretation of quantum mechanics, so it’s nothing new. And really, the argument doesn’t even go that far: Maybe, for instance, there are an infinitude of branes, and it’s really difficult but not impossible to communicate between them (perhaps it can be only done gravitationally, say), but they’re arranged some distance apart, and there’s a maximum speed of communication. In this case, even if the inhabitants of some brane or another have figured out how to invade other branes, maybe they just haven’t gotten here yet. Maybe it’s so hard that, in all of the time since the origin of the branes, nobody has ever done it anywhere within our “observable multiverse”. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [May 27, 2014, 2:22am UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/62 "2014-05-27T02:22:23Z")
> [@Robert163](#): > > In the multiple universe, infinite universe situation, in terms of probability, does this many that anything that is possible, no matter how improbable, will eventually happen. For example, is there somewhere, an exact copy of the earth, down to the milimeter, but where all the men look like adolph hitler and all the women look like marilyn monroe, but they are all born looking that way by random chance alone. No because forcing everything to happen would require more things to happen in order to force it. Its like, you’d have to have infinite cubed things happen to ensure infinity things happen… which means you need more than what you can get, so its not a match. No you can’t have everything happen, because thats just too many things… Even when infinite things have happened/existed, there’s always another thing left not done… ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [May 27, 2014, 2:38am UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/63 "2014-05-27T02:38:43Z")
> [@Little\_Nemo](#): > > Just because an infinite number of different things exist doesn’t mean that everything must exist. Look at Pi as an example of how that can be: it’s an infinitely long sequence - but you’ll never see an “A” in that sequence. Speaking of Pi, I recently ran across this tangentially related blog post: [Infinite and Non-Repeating Does Not Mean Unstructured](http://www.goodmath.org/blog/2014/05/22/infinite-and-non-repeating-does-not-mean-unstructured/). ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [May 27, 2014, 4:29am UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/64 "2014-05-27T04:29:02Z")
> [@Chronos](#): > > All your argument says is that, if there is an infinitude of universes (or “branes”, or “worlds”, or whatever), then classical communication between them is impossible. Which is in fact one of the necessary premises of the Many Worlds interpretation of quantum mechanics, so it’s nothing new. > > And really, the argument doesn’t even go that far: Maybe, for instance, there are an infinitude of branes, and it’s really difficult but not impossible to communicate between them (perhaps it can be only done gravitationally, say), but they’re arranged some distance apart, and there’s a maximum speed of communication. In this case, even if the inhabitants of some brane or another have figured out how to invade other branes, maybe they just haven’t gotten here yet. Maybe it’s so hard that, in all of the time since the origin of the branes, nobody has ever done it anywhere within our “observable multiverse”. But would you agree with me insofar as “paralllel” universes go? I can agree that we can have infinite universes, but some of them, like ours, have to have a finite number who Patrick Swayze occupying Whoopie Goldberg’s body (spoiler alert) we can’t have infinite Marilyn Monroes (and Tony Curtiss too since it is infinity!) overlapping. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [May 27, 2014, 12:45pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/65 "2014-05-27T12:45:33Z")
> [@Chronos](#): > > Cantor’s diagonalization argument isn’t relevant here. We’re not positing an entire universe identical to ours aside from the Monroes and Hitlers. We’re positing a finite-sized chunk of universe meeting that description. You can say that that chunk just needs to be planet-sized, or maybe it needs to be the size of the entire observable Universe if “just like ours” includes the results of astronomical observations, but either way, it’s finite. I don’t see what you are getting at. Any interesting (and Earth size is plenty big enough) chunk is going to have an uncountably infinite number of possible states. Not even countably infinite. Let alone finite number of states. The only way you can Mathematically argue a twin-Earth exists is to have an _broad_ definition of twin. E.g., approximately the same mass, etc. At that point, then it becomes a wholly different issue of no real interest that gets bogged down in definitions. E.g., is Alpha Centauri a “twin” of the Sun or not? People could argue both sides if slop is allowed. ---
**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:** [May 27, 2014, 1:28pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/66 "2014-05-27T13:28:12Z")
> [@](#): > > Any interesting (and Earth size is plenty big enough) chunk is going to have an uncountably infinite number of possible states. How do you figure? ---
**Author:** ![Tom\_Tildrum](https://avatars.discourse-cdn.com/v4/letter/t/e95f7d/32.png) [@Tom\_Tildrum](https://boards.straightdope.com/u/Tom_Tildrum)\ **Post date:** [May 27, 2014, 2:50pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/67 "2014-05-27T14:50:34Z")
> [@Little\_Nemo](#): > > Just because an infinite number of different things exist doesn’t mean that everything must exist. Look at Pi as an example of how that can be: it’s an infinitely long sequence - but you’ll never see an “A” in that sequence. In [base 16](http://www.wolframalpha.com/input/?i=convert+pi+to+base+16), the sixth digit of pi is A. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [May 27, 2014, 2:57pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/68 "2014-05-27T14:57:11Z")
> [@Chronos](#): > > How do you figure? Since a planet is, as someone mentioned above, arrived at—that is, it doesn’t just pop into existence—then drawing from an infinite universe it can arrive at any one of infinitely many formations. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [May 27, 2014, 3:06pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/69 "2014-05-27T15:06:36Z")
> [@The\_Second\_Stone](#): > > The evidence for other “space-time” continuums, much less infinite ones, is slim to none, with the emphasis on “none”. I believe you’re not quite correct there. First, there’s no direct evidence pro or con, which is why we’re allowed to speculate in either direction. It makes sense to speculate in both directions. Second, recent evidence regarding the polarization of the earliest light in this universe actually favors the multiple-universe theory. Don’t ask me how; it has something to do with the expansion phase and is way over my head. It was discussed on a thread here at SMDB just this year. If you’re interested, ask a physicist who might remember the key words and even understand some of it. This isn’t quite evidence that they exist, it’s evidence that corroborates a theory favoring their existence. I.e. “slim” but not “none”. > [@Thudlow\_Boink](#): > > Speaking of Pi, I recently ran across this tangentially related blog post: [Infinite and Non-Repeating Does Not Mean Unstructured](http://www.goodmath.org/blog/2014/05/22/infinite-and-non-repeating-does-not-mean-unstructured/). Thanks! The quote being ranted against annoyed me too, but I didn’t know that the randomness of digits of transcendental or irrational numbers is conjecture. ---
**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:** [May 27, 2014, 3:07pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/70 "2014-05-27T15:07:51Z")
I don’t see the connection there. The digits of pi are also drawn from an infinite set, but each digit of pi, or finite subset of digits of pi, has only a finite number of possible states. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [May 27, 2014, 3:29pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/71 "2014-05-27T15:29:07Z")
> [@Chronos](#): > > I don’t see the connection there. The digits of pi are also drawn from an infinite set, but each digit of pi, or finite subset of digits of pi, has only a finite number of possible states. True, but in postulating our universe as an infinite universe, how normalized should we assume it to be? I get that given any chunk of finite space, there’s only so many states of matter and energy that can fill it before you start repeating some arbitrary permutation (even if it be 10[sup]10000[/sup]th permutation). But this assumes an infinitely homogenous and isotropic universe as well. It’s just as easy to speculate one that isn’t. ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [May 27, 2014, 3:46pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/72 "2014-05-27T15:46:53Z")
> [@Learjeff](#): > > First, there’s no direct evidence pro or con, which is why we’re allowed to speculate in either direction. It makes sense to speculate in both directions. Because light travels at the speed of light and mass has mass, we would expect to see evidence of universes occupying the same space as ours and if they are infinite, then we would expect to see infinite evidence. Yes, we are allowed to speculate contrary, but it seems that unless the laws of physics are different than we know them to be, we cannot have infinite parallel universes, or at least cannot ever prove it, which is the same thing as far as science goes. Philosophy is a different matter. Suppose we add in time travel to space travel between these different universes. If finite, we might have missed them. But if infinite, we would have time travelers all over the place. ---
**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:** [May 27, 2014, 4:27pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/73 "2014-05-27T16:27:33Z")
Only if we assume that light and gravity can traverse between universes, which they might not. And even if they do, they might traverse them in such a way that the net effect from an infinite number of universes is finite: This is one possible explanation for the Dark Matter problem. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [May 27, 2014, 5:16pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/74 "2014-05-27T17:16:44Z")
> [@The\_Second\_Stone](#): > > If finite, we might have missed them. But if infinite, we would have time travelers all over the place. If there are infinite universes, there are infinite places to go. Nobody should be piling up anywhere. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [May 27, 2014, 5:43pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/75 "2014-05-27T17:43:11Z")
> [@billfish678](#): > > If there are infinite universes, there are infinite places to go. > > Nobody should be piling up anywhere. Unless they all went to Hill Valley, CA. November 5, 1955. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [May 27, 2014, 8:41pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/76 "2014-05-27T20:41:08Z")
> [@The\_Second\_Stone](#): > > Because light travels at the speed of light and mass has mass, we would expect to see evidence of universes occupying the same space as ours and if they are infinite, then we would expect to see infinite evidence. Yes, we are allowed to speculate contrary, but it seems that unless the laws of physics are different than we know them to be, we cannot have infinite parallel universes, or at least cannot ever prove it, which is the same thing as far as science goes. Philosophy is a different matter. Suppose we add in time travel to space travel between these different universes. If finite, we might have missed them. But if infinite, we would have time travelers all over the place. Don’t confuse “MWI” multiple universes with “multiple big bangs” multiple universes. They’re rather different. The MWI or Many Worlds Interpretation is an interpretation of quantum mechanics that explains waveform collapse without actually needing waveform collapse; it’s an alternative to the Copenhagen interpretation. Someone posted a link to that above. It’s very different than the multiverse that gives rise to an infinite number of big bangs. In either case, your argument rests on your definitions, which don’t match the definitions that physicists who postulate these things use. Regardless, for what we’re discussing here, it’s irrelevant, because an infinite multiverse would be a superset of a much simpler concept, which is an infinitely large universe. [sidebar: According to Brian Greene, if the universe is infinitely large now, it also was at the big bang. Oddly, this doesn’t contradict the multiverse concept, where big bangs spawn from something else. I admit I don’t understand that a bit, but I’d want to at least come to terms with what the experts say about it before I called it impossible or completely hair-brained. (Or hair-braned, as it might turn out to be. 😉 )] If the universe is infinitely large, then there is a countably infinite number of galaxies, stars, planets, etc. So, the question here is whether that implies that anything we can imagine must exist. Well, we can imagine a lot of things that simply aren’t possible. But we _could_ imagine things that seem very possible but it seems equally absurd that they should exist “somewhere out there”. For example, a world identical to this, but where I misspelled different words in this post. ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [May 27, 2014, 9:22pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/77 "2014-05-27T21:22:39Z")
> [@Learjeff](#): > > Don’t confuse “MWI” multiple universes with “multiple big bangs” multiple universes. They’re rather different. The first is infinite universes occupying the same space. The second is a an infinite series of universes like ours occupying different spaces, like galaxies. I’ve got that. If we, or more advanced civilizations can’t detect them, it is a moot point, we can never prove them except by concept. If they can be detected by super-advanced civilizations, and those detections leave behind any light at all, even that of a firefly, there would be an infinite amount of fireflies and light from infinite super-advanced civilizations would have overcome us by now. It’s the Marilyn Monroe effect everywhere in our universe as Chronos describes it. If they can detect us and leave no residue at all, I suppose you could still argue for it. But as I have not heard any convincing evidence for an infinity of any kind of mass or energy, I’m not going to start with “there must be infinite universes” because the Sheldon Cooper’s of the world think it is conceptually possible. I can wrap my head around mathematical infinities, and monkeys at typewriters infinities as long as they are just concepts. There isn’t the slightest evidence that there is any infinite noun existing in anything but our minds. And I find that by itself to absolutely amazing and wonderful. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [May 27, 2014, 9:56pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/78 "2014-05-27T21:56:40Z")
> [@Chronos](#): > > How do you figure? Take a single atom in that space. It’s location can be in anyone of an uncountably infinite number of places. That alone gets you to a reasonably hefty infinity. I think many of the differences you and I are having is in the terminology. E.g., what does “sets of states” mean. I mean it in a purely Mathematical way. The Earth at a given exact moment is one state. It flows thru a sequence of states. The set of possible “Earth” states is all possible states of anything you could cram (or not cram) into an Earth+ sized chunk of space, whether realizable or not. If someone is doing a counting argument, then this is something they have to acknowledge. If you are going by purely Physics developmentally possible stuff, then the quantum stuff splitting up the development timeline is also so massively infinite that that’s a no go as well. But I have not read any papers that really go this way. The ones I’ve seen are purely counting arguments by people that apparently have never heard of Cantor. ---
**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:** [May 27, 2014, 10:03pm UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/79 "2014-05-27T22:03:41Z")
> [@](#): > > Take a single atom in that space. It’s location can be in anyone of an uncountably infinite number of places. Probably not true. ---
**Author:** ![j\_sum1](https://avatars.discourse-cdn.com/v4/letter/j/8baadc/32.png) [@j\_sum1](https://boards.straightdope.com/u/j_sum1)\ **Post date:** [May 28, 2014, 12:01am UTC](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219/80 "2014-05-28T00:01:04Z")
> [@Chronos](#): > > Probably not true. I did not know that space and time were quantised. I know it has been conjectured – plank length and all that. But AFAIU it is still just a conjecture. If space is not quantised that necessarily leads to an uncountably infinite number of states even for just two objects. This cannot be reasonably represented by a countably infinite number of particles in an infinite universe. I am with **ftg** here. I think that Cantor’s reasoning applies. That said, the OP situation is slightly different – a duplicate earth not identical to ours but like ours with a lot of Marilyn Munroes and Hitlers running around. Now we are talking about a different subset of all possible states – not a single state exactly identical to earth but a wider set that is similar to earth. This is an uncountably infinite subset of an uncountably infinite superset. And we propose that there will be a non-zero probability that it will occur with a countably infinite number of particles. I am at the edge of my maths here but I don’t think that works. I think the probablity of a similar earth occurring has to be zero. The other thing that needs to be mentioned is that we are limited to reachable states. In other words, laws of physics chemistry and biology apply that effectively restrict the number of similar earths that we might need to consider. This doesn’t change the problem. Applying a further restriction still leaves us with probability zero. However, if we consider only reachable states, then this does make the problem easier to visualise. Correct me if I am wrong here, but the laws of biology, genetic diversity and the mechanism of reproduction rule out an earth populated by Marilyn Munroes. (As disappointing as that might be.) [Previous page](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219.md?page=3) [Next page](https://boards.straightdope.com/t/multiple-universes-infinite-universe-and-probablity/689219.md?page=5)