Tuesday, February 16, 2010

So I was listening to this Radiolab podcast, an interview with Brian Greene. Apparently, if the universe is indeed infinite, there could be an infinite number of duplicate "Earths" and infinite near-duplicates somewhere out in the universe. If you flip a coin five times in a row, you'll have a certain pattern, like heads-heads-tails-tails-tails. Flip it five more times and you'll probably come up with a different pattern. But flip long enough and eventually you'll have flipped all possible combinations. Then, of course, the next set of five you flip is guaranteed to repeat one of the patterns you've done already. And if you live forever and flip infinitely, you'll flip each possible combination an infinite number of times. Well, the Earth has a finite number of atoms that make it up. An unfathomably large number, of course, but a finite one. So, there are a finite number of ways that this number of atoms can be arranged. A very very very large but finite number. So if you go out into the universe and look for planets, each one is going to be different from Earth in some way, right? Right. But if you go out long enough, you'll have exhausted all possible combinations of the way a planet's atoms can be arranged. Then, see, you'll inevitably find a planet that is an exact duplicate of a planet you've already visited, such as Earth. Keep going and eventually you'll come upon another Earth duplicate, and yet another, and another—remember, we're talking about ∞ here!—and another, and another.... So, yeah, an infinite number of Earth clones. Plus an infinite number of almost-clones, where everything on Earth is exactly the same, but maybe some wine glass on some table in some restaurant is sitting two inches to the left of its counterpart's position on our Earth. So basically, everything in the universe is infinitely duplicated elsewhere in the universe. There are infinite "you"s out there.

As weird as this sounds—and I'd have to say it must be the weirdest thing I've ever heard—what's weirder is that it ACTUALLY MAKES SENSE. I can't stop thinking about it. I can't stop thinking about how out there somewhere, there are an infinite number of Matts typing a sentence identical to this one, on an identical computer, in an identical apartment, in an identical New York, on an identical speck of dust known to its inhabitants as "Earth".

12 comments:

  1. Since when is the universe infinite?

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  2. well, we don't really know of course. but i think that's the most widely held theory.

    in the same podcast he also talked about the multiverse theory, which suggests that our observable universe is just one of an infinite number of bubble universes inside a cosmic swiss cheese that is eternally expanding.

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  3. also: somehow, *possibly*, it is technically more likely that we--you and I, our earth and all we consider to be real--are in fact a computer simulation being run by an advanced alien race, than it is that we are actually "real".

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  4. As far as I know the most widely held theory is that the universe (as in, this one, the one we're in) is finite but expanding (and may continue to expand forever).

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  5. Also, you could be a Bolzmann brain. #dontgetmestarted

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  6. i'm sure we could easily check this somewhere, but i *think* the most common theory is that the universe is both infinite and expanding...

    i would bet you, but i don't have anything to bet, plus, i don't want to lose.

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  7. yeah actually that wasn't as easy to determine as I thought it would be. especially because there's this conflation of infinite vs. finite and flat vs. curved. a curved universe would definitely be finite, but I'm pretty sure that flat doesn't necessarily imply finite. I'm going to axe my (physics-inclined) ex.

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  8. yeah, flat could be infinite.

    god we sound smart. ha.

    that there are human brains capable of understanding the equations that deal with this stuff is an endless wonder, as mysterious as the universe itself.

    (i wish i could find a link to the podcast. it's a slightly old episode.)

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  9. Whoops, I meant to say flat could be finite. As in, if a finite, flat universe expanded forever, it would become infinite with an infinite amount of time.

    Is Brian Greene the guy who did that book and PBS series on string theory?

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  10. he is the john cusack of string theory:

    http://www.superstringtheory.com/people/bgreene.html

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  11. Wow, no joke. Don't be fooled by the pic though. I saw the documentary. He's a complete tool. Also I'm pretty sure string theory has suffered some embarrassing hits of late.

    ~~I heard a rumor~~

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