YES! YES!
My god, thank you. I read this article last week and it immediately struck me: “Wait… just because everything is possible in an infinite space doesn’t mean everything actually happens…” and I sat down to remember why. This is exactly what I was remembering (its been too long since Combinatorics!), and I think this little bit of reasoning knocks the article’s logic right on it’s silly ass.
Im sure there’s an answer to this, but the article doesn’t have it.
-C
The most obvious one is Zeno’s paradox, but in reverse.
That is, if you define a random, finite universe (say, on your desktop, for example) and find any amount of repetition whatsoever (paper of the identical dimensions perhaps), then a random, infinite universe will have infinite chances for repetition. It seems to me this is the basis for the ontological argument, couched in slightly different terms–if the universe is infinite, God must exist somewhere.
The trouble is, as finite beings we generally have no intuitive grasp of infinite concepts. I don’t know what kind of logic holds for infinity. It seems entirely possible that whatever logic we apply for the infinitely small does not necessarily apply to the infinitely large. (For example, we often have far less difficulty in finding meaningful infinite sums for bounded values than we do for unbounded ones.)
It’s also conceivable that any sufficiently large finity will be indistiguishable from infinity.
ok…it’s really really REALLY big
basically what your saying is that such a number is so large that it doesn’t matter what unit we use because the diference between the smallest thing we can think of and the largest is not even noticable enough to round off to.
Maximum C/Spiritus Mundi - Intuitively your statement makes sense but wouldn’t the rest of the Level I universes pretty much have the roughly same level of entropy as ours? If that was the case, it seems unlikely that given a similar distribution of matter and energy, our universe would be filled with planets and stars while everything beyond is filled with a “white noise” of repeating chaotic particles. Hopefully someone with a better understanding of thermodynamics than I will be along shortly.
The article gave some reason for why we didn’t live in an “island universe”, can’t remember though.
This thread has gone far beyond where I can contribute anything meaningful besides a question. (Maybe this is obvious to everybody except me.)
When you are talking about a duplicate earth, are you saying it has to be exactly duplicate in every detail at every level of existence/experience? Let me try to explain. If I have a machine that can make an exact duplicate of a penny, down to the last imaginable detail, there would still necessarily be a difference between the two of them. One of them is HERE and one of them is THERE. The moment the duplicate pops into existence, it starts having different experiences, and is no longer an exact duplicate.
It is not enough to have a duplicate earth; it is necessary to have an exactly duplicate universe as far as it is possible to experience anything. If on earth I look through a telescope and my eye intercepts a particular photon from the edge of “my” universe, my duplicate must be seeing the identical photon from the identical source in “his” universe.
Should I understand, then, that the only way to have an identical/duplicate earth is to have it be in an identical/duplicate universe that has no physical/temporal connection or relationship to our universe? We can say that the other “universe” is just so unimaginably far away that it can never be experienced in anyway by someone in our universe—but then aren’t the universes in different “locations”?
Does this make sense to anyone?
Just a thought I had: If the universe DOES contain an infinite number of Hubble Volumes (essentially, universes), with an infinite number of alternate versions of me and identical versions of me - then isn’t any thought I have actually a communication between me and the legions of identical versions of Mr. Excellent? After all, if I have a thought, those other identical Excellents are having the exact same thought, and are aware - as I am - that the other Excellents are having that thought. So, if I think to myself “Hi, infinite legions of identical Mr. Excellents!”, those other Mr. Excellents will know I thought it, because they’ll be thinking it themselves. So in a sense - is this communication between me and the alternate me’s?
If you carefully read the article in question, you might notice in the Level III/Level IV Multiverse discussion that they also talk about a hypothetical universe in which all possibilities exist all at once. I’m not sure I buy into the feasibility of such a concept, but in that case, your doppelganger might potentially exist in the same time and place, though simply one dimension removed.
Back again… I bought the Scientific American for May 2002 and must say that it is an awesome Doper issue, not only this parallel Universe stuff, but a good article on synesthesia, and Otzi the gay caveman!.
Anyway considering type I universes I do have some reservations in calling such a system a group of parallel universes rather than 1 universe of very large extent.
The simplified argument goes something like this, if the universe is not to have edges (edges are quite a strange concept to imagine for a universe, theoretically cause all sorts of nastyness near the edges), the universe can be either infinite or curved in upon itself (like the surface of a sphere). Current observations from our point in the universe suggest the universe is very very flat. So flat that if the universe is a sphere it is one of very large size (much more than the 10[sup]10[sup]118[/sup][/sup] meters needed to produce a duplicate 14 billion light year sphere to the one we exist within ) or if not a sphere it is perfectly flat (and therefore if we don’t want edges, infinite in size).
Our observations also tell us that within our 14 billion light year sphere (our ‘little sphere’) at the larger ends of measurement scales everything is very evenly distributed, so even in fact, that we can expect the universe beyond our ‘little sphere’ to be pretty much similar.
If we assume the universe is similar throughout then if all things are quantised then there must be identical ‘little spheres’ to our own.
This is all valid reasoning, but not what can really be called proof. Since by the vastness of the universe being considered, it can be noted that we in our observations are only viewing an incredably small amount of it. And the anphropic principle means we couldn’t be observing the universe from a point within it where life could not exist (for instance a very sparce area of space) so we should nnot be surprised that the ‘little sphere’ we are in is full of enough matter and energy for stars planets and eventually life to have formed within it.
Cheers, Bippy
I think what they are talking about is the statistical likelyhood of there being a universe that at this particular instant is exactly like ours. For example, the article gives the following figures:
-your closest identical copy is 10 to the 10^28 meters away.
-there should be a sphere of radius 100 light-years identical to the one centered here about 10 to the 10^92 meters away
-there should be an entire Hubble volume identical to ours about 10 to the 10^118 m away.
As you can see, the more complex the system, the further away we have to go before we are likely to encounter a duplicate. So “only” 10 to the 10^28 there is another you, just like you at this particular instant on some Earth-like planet in a similar but not identical universe. But while you are reading this message board, maybe he goes outside.
Now a mere 10 to the 10^118 m, your clone is hanging out in a universe indistinguishable from our own. Of course the next instant a supernova may explode in our galaxy and not his.
It’s more of an exercise in probability than an actual predictor of where to find another you.
No. You may physically be identical to your Mr. Excellent a couple of universes over but you may have experienced a very diferent life. Since you don’t know what’s going on in his world and he doesn’t know what’s going on in yours, you are no more communicating with him than two regular Earth twins in different cities mentally communicate with each other.
So don’t go all Jet Li trying to become ‘The One’ quite yet.
Here are a few mind zappers for you guys, if this article is correct then…
There exists at least one Hubble Volume somewhere within the 10[sup]10[sup]118[/sup][/sup] meters where every coin flip that has ever occured has come out heads, every dice roll has come out 6, every poker hand has been 4 royal flushes.
Some interesting possibilities also arrise if time travel or faster than light travel is in fact a possibilityand if it can be controled, then it must have occured somewhere (many many places) in the huge universe (type I multiverse). Such capabilities combined with immortality (probably very easy to achieve by comparisson) will cause a breakdown in the independance of all the space separated ‘tiny spheres’ since beings capable of f.t.l. travell and or time travel could cross the distances between them. What these beings are doing is a point of interesting sci-fi style debate.
Also since the theory predicts that every possible ‘tiny sphere’ exists many times, that leads to every possible being exists, there are Daleks, Cthulhu, Dragon like beings (constrained only by physical possibility).
Cheers, Bippy
If the universe is truly infinite, then I’m not sure physical laws even apply, other than quantum laws. Things like the behaviour of gases are essentially statistical - air pressure is the result of an average momentum exerted upon things by the random motion of air particles.
So there must be some universes in which just through variance things behave very strangely. Like the universe where every poker hand ever dealt came up a royal flush.
It’s interesting to think about what a FTL trip would look like. As you zoomed away from Earth, it would look older and older, until you got out to the Hubble distance, at which point our solar system would just be in the process of being formed. But from there, the part of the universe that we see from here as just being created would be as old as our solar system is, and from there you could see another 15 billion miles. Kind of like having headlights on a car driving at night.
er, light years. Not miles.
This… doesn’t explain the problem at all. It isn’t a question of not grasping infinity. If I have an infinite set, then saying that each member is chosen randomly doesn’t prove diddly squat because it’s perfectyl consistant to say that only one state repeats. Or that many states repeat, but just not in a way that gives rise to another parallel universe.
This isn’t intuative feeling - it’s the pigeonhole principle, which says: If you choose x > n elements from a set of n elements, you must choose some element more than once. Thats ALL you can say with certainty.
Maybe statistics says that, given the infinite size of the universe and the fact that we assume it varies equally throughout, it’s highly probable that all things repeat- like rolling a dice an infinite number of times, you expect to get all sides eventually.
BUT IT IS NOT PROOF. If the article can’t overcome this, in my mind, it’s junk science and speculation.
-C
Hey, I’ll completely agree with you that the verbiage “Parallel Universes Really Exist” oversold the article. I’ll even agree with you that there’s definitely a large degree of speculation going on there–maybe I’d even call it indulgent. But please don’t throw out the old “NO PROOF” canard. Science speaks in probabilities, not proofs. Proofs are for mathematics.
Our visible universe appears by most accounts to be finite. As the multiverse’s size approaches infinity, the probability for our exact repetition approaches unity. I’m not saying you can’t argue against that logic, nor do the authors for that matter (see the concluding paragraphs). Sure, there can be static repetition. But the concept of infinite size implies infinite variations on whatever states are possible. In order for the die analogy to match, we would have to either suppose that the multiverse would “choose” to only throw the die a finite number of times… and/or that the die itself is infinite and that each chance might occur only once or not at all.
Seems to me that there is at least reason enough to entertain the ideas presented. It could be argued that the purely speculative end of science should be kept out of publications such as Scientific American, but I personally don’t have too much problem with giving them a little latitude. It’s not like they’re publishing L. Ron Hubbard…
If the universe is infinite as to size, and has enough particles to replicate itself an infinite number of times, there would still be the question of infinite time.
Just like the monkeys randomly punching out Shakespeare, anything could happen I suppose.
The time would seem to be the limiting factor…how many times would the “multiverse” have to go through the permutations to get it just right. Did my doppleganger forget his glasses this morning, have to go back home, and then have a wreck he didin’t have if he was me? Well, that universe would have to start from scratch to get him to be posting here on SDMB.
15 billion years (or whatever) down the tubes.
Just that one mundane little factoid blew it for that doppleganger universe.
Then add up all the little factoids that would have to fall perfectly in place from the big bang until now and you are faced with another “significantly large” number. With every event directly affecting the events that followed, just one small glitch and that path will stray.
That’s the problem I see with starting with a big bang. A start. Sure, with an infinite number of universes I suppose anything could be possible. They would just have to happen, in perfect order, before the age of that supposedly expanding universe got so large that the space between the particles expands to the point where no interaction could take place.
Seems like if our view of big bang/expanding universe is correct, you will only have maybe 50 billion years or so with each shot to get every single fact right through that entire 50 billion year period, or it will all have been for naught.
But, on the other hand, an infinite number of anything might also mean an infinite number of unique states, never to be replicated.