Paralell Universes - SA special report

[daniel_i_l]

A few days ago I got a Scientific American "special report" about parallel universes. They said that there's a type of PU ("type 1") that definatly exists if the universe is infinite and uniform - since there's only a finate amount of ways to distribute matter in a certain volume, then matter configurations (such as our solar system) will start repeating itself an infinite amount of times, meaning that there're infinite copies of Earth and everyone on it.
What do you think about that?

 

[B.E.M]

Could you find a link or provide some authors? I would like to google that.

Just recently I wrote a SF script with a 'quantum imortality' idea, using teleportation to argue it, but I didnt know that the idea was an old one at the time.

I also thought I was being original because instead of resorting to QM, I started with 'what if the universe is very very big..' ..sigh

 

[marcus]

A few days ago I got a Scientific American "special report" about parallel universes. They said that there's a type of PU ("type 1") that definatly exists if the universe is infinite and uniform - since there's only a finate amount of ways to distribute matter in a certain volume, then matter configurations (such as our solar system) will start repeating itself an infinite amount of times, meaning that there're infinite copies of Earth and everyone on it.
What do you think about that?

Around about 2004 a cosmologist named Max Tegmark wrote a Sci Am article about Multiverses that included this idea.

I read it online. It had various types including this "Type I" which was if space is infinite there would somewhere be a planet just like Earth except the Confederates won the Civil War. Stuff like that. that is just the mathematics of infinity, as you point out. It is not physics.

the latest data makes it look increasing likely that we have a nearly flat universe which is NOT infinite.
People keep getting errorbars for the curvature that are over on the positive side. So it looks increasingly like the three-sphere S³ but the data is still not good enough to say. Still could be flat infinite.

If positive curved almost flat but not quite flat----and finite----eventually gets verified, then the Type I multiverse fantasy does not apply to reality.

In the rest of the Tegmark article there was a great deal of baloney about Many Worlds quantum mechanics and Eternal Bubbles of Inflation fantasy and Landscapes of many realities. I was kind of disgusted and even wrote to him about about a point I thought particulary flakey. Unfortunately you sometimes need to take SciAm articles with a bit of salt.

If you Google "Tegmark Multiverse" you might well get the SciAm article---which at least used to be freely available online.

 

[EL]

since there's only a finate amount of ways to distribute matter in a certain volume, then matter configurations (such as our solar system) will start repeating itself an infinite amount of times, meaning that there're infinite copies of Earth and everyone on it.

I don't get this.
For the first, why is there only a finite amount of ways to distribute matter in a certain volume?
Secondly, assuming that is really the case, why would the universe start repeating itself? Surely some parts of the universe must start repeating, but why couldn't it be that the Earth only exists a single time? (Except for that it somewhat constradicts the Copernican principle...)

 

[B.E.M]

Thanks!, I did, and found among other things a wiki article
http://en.wikipedia.org/wiki/Multiverse_(science)"

Level I: (Open multiverse) A generic prediction of cosmic inflation is an infinite ergodic universe, which, being infinite, must contain Hubble volumes realizing all initial conditions - including an identical copy of a given person about 10^10^29 meters away.

 

[B.E.M]

I don't get this.
For the first, why is there only a finite amount of ways to distribute matter in a certain volume?

I would also like to understand this. Is it some quantum mechanical result that the number of configurations within a volume are actually countable, or does it mean within some 'sensible' degree of error?

One I would be happy enough with for example is that the positions of particles are the same within the range of a chemical bond and the energies are close enough that the exact same configuration of molecules form.