I was reading the book “the beach.” You may have seen the book with Leo DiCaprio, but I had to loan it because that was all that was available at the time. All in all it was an okay book, but Richard, the protagonist mentioned something at one point, which really made me think.

If the universe is infinite, then that means that its is possible that not only is there another world like earth, but also there is, on one of those worlds, a guy exactly like me. In fact, there are infinite copies of me, and infinite copies of me who, by chance might be slightly different (different hair color, etc). If we exist because a random coming together of circumstances allows it, no matter how small, after an infinite number of chances for that to reproduce itself, it happens.

What the character eventually reasons is that somewhere in the universe, his doppelganger is taking a different course of action (kissing the girlfriend of his friend) while he does another.

I think this is actually a very cool way of thinking. It makes much more sense than to believe we are alone in this universe. If it is possible for aliens to exist, even by the smallest fraction of a possibility, then they must exist? It seems like that is the case…

Infinite, but variable. Its like notes of music… All the same, but different everytime they’re rearanged. “Notes” in other parts of the universe may not even be remotely the same as here even, or exist at all. You are only you, there are no copies.

Okay, but I seriously doubt there is a copy of the OP on the other side of the universe that thinks the same as he does, or is like him but “opposite” (bizarro world scenerio). It would be great to think that there is even another human species like ourselves out there, even that is unlikely. Possible, but unlikely…

If the universe is truly infinite, then there will be some random combination of atoms elsewhere that exactly mimic the earth. You can even do the calculation and figure out how far away on average such a place is likely to be (and it’s a huge number - like10 X 69 light years or something).

It’s basically the infinite number of monkeys writ large. Given an infinite universe and the ability of atoms to come together in essentially random patterns, we exist somewhere else. Along with infinite variations. Furthermore, some of our other ‘selves’ live in a region of space identical right out to the limit of their ability to see the universe.

-AFAIK, modern cosmology doesn’t consider the universe to be infinite

-Even if it were, that doesn’t mean that anything can happen, only any possible thing - impossible things are still impossible.

-I’m not so sure on this one (perhaps someone can advise), but I think even within an infinite set, it is not guaranteed that all possible configurations must occur.

It would be strangely comforting to think that somewhere there’s another me that hasn’t screwed up as often or as royally as I have, someone that’s having exactly the kind of life I wanted but never achieved, and probably doesn’t whinge half as much as I do!

If the Universe really is infinite (and there’s no evidence it is), then there would be infinite exact copies of ourselves, typing exactly the same messages on exactly the same SDMB board at exactly the same time.

It’s possible, but is there really any reason to think that, even if the conditions to make a perfect duplicvate of the Earth came together, it would even follow so similar a path as to produce people at all, or that those people would have precisely the same history as us, down to producing the same individuals? I have trouble replicating lab experiments, with far fewer variables. In ther words, the probability is wayyyyyy down there an inconceivably great distance from the decimal point. I think the odds of all the air molecules gathering by chance in one corner of my room is greater.

There’s an appeal to the existence of a parallel world, rather than its mere potentiality. Sometimes it shows up as another “dimension” (most readers and writers, I suspect, don’t really understand the implications of that term), or as some manifestation of the “many worlds” view of QM, or something. It gets used in science fiction and fantasy all the time, generally with people or things hopping from one probability line to another. One classic use of this was in Fredric Brown’s novel What Mad Universe?, but Brown was doing it pretty much tongue-in-cheek, and was making fun of SF cliches throughout the book.

Interesting… that book is one that I return and re-read quite often and although I would say it contains many elements of a typical parallel-probability-lines story, my impression is that, rather than existing in alternative realities, the parallel worlds in this book seem to be within the same universe and reality, merely physically separated from one another.

As an aside and as a means of demonstrating probability and the infinite…

Allow me to quote Steve Goodman:

“The law of averages says anything will happen that can
But the last time the Cubs won the National League Pennant
Was the year we dropped the bomb on Japan.”

One example that brings the point about the non-inevitability of things happening:
I have an article by a computer scientist who performed the whole “infinite number of monkeys on a typewriter reproducing Shakespeare” thing. I don’t recall his name, but can look it up. What he did was to model the situation was a random number generator generating the letters of the alphabet, plus spaces and punctuation marks. Even after allowing long periods of running, these virtual monkeys didn’t come up with even a fragment of recognizable text. So he stacked the deck in their favor by using chunks of Shakespearean text to produce the relative probasbilities of letters appearing, and used that in weighting trheir chances of turning up that letter (so if you went through the results, “e” would show up as by far the most common letter, for instance, rather that merely being there 1/26th of the time – or whyatever, after yuou allowed for spaces and the like). Still, no recognizable text. So he upped the ante by generating probabilities of pairs of letters. SDuch “second-order” monkeys started showuing up things like words, but not a lot of them. So he went on to “third-order monkeys”, and Fourth- and Fifth-order. Now they were coming up with words, sometimes even on combination (and, interestingly, often obscene). But he was still far from recovering even a portion of recognizable text. You’d think there was a good probability of at least recovering the text that he used to generate the probabilities. But no.

As he put it, there was “insufficient noise” in the pseudo-random number generator he was using to visit every point in the solution space. Even if he let his program run forever, it wouldn’t reproduce his original text, even though there was clearly a finite possibility of the text’s appearance. Part of the likelighood of something’s occurring depends in part on the method of choosing your random number – there are plenty of examples of this sort of thing in probability theory, which is frequently weirder than you’d expect. So even though there’s a nonzero probability of something happening, there’s no requirement that everything potentially possible must happen. And, of course, in the Real Universe, we don’t have truly inginite time.

I’m no mathematician (very very far from it, in fact) but it’s my understanding that there are an infinite quantity of integers (whole numbers). That’s an infinite number of numbers. That infinity doesn’t include a single non-whole rational number such as 3.5, so you can obviously have “infinity” without “infinity” being required in some fashion to include every conceivable possibility. And since you can consider the set of all rational numbers, of which there is also an infinite quantity, you’re now faced with “not all infinities are equal”. This second flavor of infinity contains 3.5 whereas the first did not. Oh, and neither of them contain pi, but I can posit a third infinity consisting of all the real numbers. Oops, doesn’t contain the square root of -1, hmm.

For anything that is “infinite” there may yet be conceivable members or occurrences that, despite being conceivable, ain’t there. Infinite ≠ all-inclusive. Infinite = not finite in scope.

Still, I think that a person could make a fairly compelling argument that a world existing that is identical to earth is a possible configuration in the universe that we’re in.