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”.
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…
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.
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.
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.
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”.
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.
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.
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.
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.
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.
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.
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.
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.)
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