Comment author:Viliam_Bur
16 September 2011 12:10:04AM
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How would things change even if universe repeated itself?

Even then there would be no difference between repeating and non-repeating universe.

As an example, try to imagine 100 universes, each one exactly the same as our, in every last detail. Is it somehow different from having only 1 universe? No. Even infinitely many universes, as long as they are exactly the same, don't make any difference.

Now try to imagine one universe that somehow (despite the second law of thermodynamics) repeats. It follows the same laws, so it repeats exactly the same way, in every last detail. Is it somehow different from only repeating once? No.

Comment author:Viliam_Bur
24 October 2012 02:10:31PM
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I have no material that directly says that.

Indirectly, though, what experience do you expect if there are 100 universes exactly the same as our in every detail, as opposed to if there is only 1 such universe?

Comment author:Baughn
24 October 2012 06:51:32PM
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The same, if that was the entirety of existence.

Since we're postulating multiple universes, that's probably pretty unlikely though. I would expect to have an increased probability of existing in a universe with more copies, proportionally to the number of copies.

Comment author:Viliam_Bur
25 October 2012 07:33:25AM
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So, let's suppose there is a universe A which exists only once, and a universe B which exactly repeats forever. Those universes are different, but a situation of "me, now" can happen in both of them. (Both universes happen to contain the same configuration of particles in a limited space at some time.) Then, I should expect to be in the universe B, because that is infinitely more probable.

Unfortunately, I don't know whether I just wrote a nonsensical sequence of words, or whether there is some real meaning in them.

Comment author:Baughn
26 October 2012 11:34:17PM
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No, it sounds pretty meaningful to me.

I'm modeling this as if we have an (unbounded) computer executing all possible programs, some of which involve intelligences.. usually embedded in a universe. The usual dovetailer model, that is.

In the case you described, there would be two programs involved. One computes my life once, and then halts. The second runs the same program as the first, but in an infinite loop. And yes, in this case I would expect to find myself in program B in most samples. (Although, as I wrote that, there's no way to tell the difference.. make the obvious correction to fix that.)

I described it as all possible programs, though, which would certainly include things such as boltzmann brains. The reason I don't see that as a problem is.. the computational density of (my?) mind, strictly speaking, is what matters; not just the total number of instantiations, which over an infinite runtime is a nonsensical thing to ask about. Certainly there would be an infinite number of boltzmann brains, but they're rare; much rarer than, say, a cyclic universe.

Well. That said, the apparent scarcity of life in this universe, as opposed to computation-hungry but boring things like stars, seems to be a decent counterargument. I'm not sure how it'd work out, really. :O

Comment author:jvdubois
28 October 2013 05:39:11PM
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I think this sentence does not make sense. If a universe has some configuration, then it IS the UNIVERSE. It does not make sense that there are 100 of them

I imagine it like a sequence of numbers. There is 0, then there is 1 etc. It does not make sense that if you have sequence:

1,2,8,5,1

That there are two different occurences of a thing "number one. No matter how "many times" the number was used, it is still fundamentaly the number.

I think Elizier himself used a very good example of how things work like. Imagine that everything you know about our universe can be coded into a sequence of numbers. Everything - all its history etc. Now what meaning it has from inside of this universe that some powerful alien race with a lot of computing power can take this sequence and load it into a memory of some supercomputer? What if they load it and delete it it twice or million times? What if they load it on two computers simultaneously? It does not matter from within the universe. It just is.

## Comments (245)

OldEven then there would be no difference between repeating and non-repeating universe.

As an example, try to imagine 100 universes, each one exactly the same as our, in every last detail. Is it somehow different from having only 1 universe? No. Even infinitely many universes, as long as they are exactly the same, don't make any difference.

Now try to imagine one universe that somehow (despite the second law of thermodynamics) repeats. It follows the same laws, so it repeats exactly the same way, in every last detail. Is it somehow different from only repeating once? No.

I'm inclined to think "yes", actually. I think redundancy matters..

Before expounding on that, though, could you point me at any material that says it doesn't?

I have no material that directly says that.

Indirectly, though, what experience do you expect if there are 100 universes exactly the same as our in every detail, as opposed to if there is only 1 such universe?

*1 point [-]The same, if that was the entirety of existence.

Since we're postulating multiple universes, that's probably pretty unlikely though. I would expect to have an increased probability of existing in a universe with more copies, proportionally to the number of copies.

*0 points [-]So, let's suppose there is a universe

Awhich exists only once, and a universeBwhich exactly repeats forever. Those universes are different, but a situation of "me, now" can happen in both of them. (Both universes happen to contain the same configuration of particles in a limited space at some time.) Then, I should expect to be in the universeB, because that is infinitely more probable.Unfortunately, I don't know whether I just wrote a nonsensical sequence of words, or whether there is some real meaning in them.

*0 points [-]No, it sounds pretty meaningful to me.

I'm modeling this as if we have an (unbounded) computer executing all possible programs, some of which involve intelligences.. usually embedded in a universe. The usual dovetailer model, that is.

In the case you described, there would be two programs involved. One computes my life once, and then halts. The second runs the same program as the first, but in an infinite loop. And yes, in this case I would expect to find myself in program B in most samples. (Although, as I wrote that, there's no way to tell the difference.. make the obvious correction to fix that.)

I described it as

all possibleprograms, though, which would certainly include things such as boltzmann brains. The reason I don't see that as a problem is.. the computational density of (my?) mind, strictly speaking, is what matters; not just the total number of instantiations, which over an infinite runtime is a nonsensical thing to ask about. Certainly there would be an infinite number of boltzmann brains, but they're rare; much rarer than, say, a cyclic universe.Well. That said, the apparent scarcity of life in this universe, as opposed to computation-hungry but boring things like stars, seems to be a decent counterargument. I'm not sure how it'd work out, really. :O

I think this sentence does not make sense. If a universe has some configuration, then it IS the UNIVERSE. It does not make sense that there are 100 of them

I imagine it like a sequence of numbers. There is 0, then there is 1 etc. It does not make sense that if you have sequence:

1,2,8,5,1

That there are two different occurences of a thing "number one. No matter how "many times" the number was used, it is still fundamentaly the number.

I think Elizier himself used a very good example of how things work like. Imagine that everything you know about our universe can be coded into a sequence of numbers. Everything - all its history etc. Now what meaning it has from inside of this universe that some powerful alien race with a lot of computing power can take this sequence and load it into a memory of some supercomputer? What if they load it and delete it it twice or million times? What if they load it on two computers simultaneously? It does not matter from within the universe. It just is.