**From:** *geodesicallyincomplete@warpmail.net*

**Date:** Mon Apr 21 2003 - 16:12:42 MDT

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"Paul Hughes" <psiphius@yahoo.com> wrote:

*> *Inside* our level 1 multiverse, and depsite its infinite size, does it
*

*> not also have a finite time to go before its demise? And when I say
*

*> demise, I don't mean our visible universe, but our entire infinite
*

*> level 1 multiverse. Demise being defined here as the end of stars,
*

*> galaxies, completion of proton decay, etc.
*

Yes and no.

All the different regions like our observable universe can be seen as

starting at the same time and evolving at the same speed. (The energy

density is homogeneous in the "internal" space and time coordinates, the

ones where the universe-bubble ("universe", "thermalized region") is

spatially infinite.) This means that far-away parts of the bubble will

become more and more boring in the very long term, just like our part.

So while, say, a world much like Middle-Earth really exists in this

theory, it (and you) will have secondlawed to oblivion by the time you

can get there. :-)

That's the 'yes' part of the answer, with a few reservations: there is no

one moment you can point to as being the "end", and we might be able to

keep alive anyway (in a "Dyson scenario", or if there's a way around the

second law).

The 'no' part of the answer is described somewhere in the paper "Many

worlds in one" by Garriga and Vilenkin, found here:

http://xxx.lanl.gov/abs/gr-qc/0102010

The second law is only statistical: entropy will actually go down in very

rare cases. This means that for any length of time, there is a very small

but finitesimal (nonzero, "finite") probability that a civilization will

be able to survive for that length of time due to thermal fluctuations.

The longer the time, the smaller the probability; but if there are

infinitely many civilizations, then infinitely many of them will be alive

at any time, even though almost all will have died out. In that sense,

the universe lives forever, fuelled by extreme improbability.

I think this leads to something similar to what people have called

"quantum immortality": if the many-worlds interpretation is true and if,

whenever you die in some worlds and live in some worlds, your

consciousness is always continuous with one of those worlds where you

stay alive, then a consequence is that your consciousness never stops,

and you will experience more and more improbable events that cause you to

stay alive. Something similar would be true in the infinite universe

("big universe immortality", maybe): you would always live on as one of

those versions of you (in different regions of the universe) that happen

to stay alive.

I think this is nonsense, though, based on a wrong view of identity,

probability, and so on. Those who believe their probability measure is

redistributed among their surviving copies should now believe in this

silliness whether they believe in the MWI or not.

A corollary of "quantum immortality" ("big universe immortality") is

"quantum suicide" ("big universe suicide"): if you set up a quantum

experiment that kills you unless you win the lottery, you will find

you're in one of those worlds (parts of the universe) where you won the

lottery. If this is true, then you could also distinguish experimentally

between Copenhagen and many-worlds (between a small and an infinite

universe) by selective suicide, though this wouldn't convince other

people. (If you did this to someone else, it would be "quantum murder",

as in the case of Schrödinger's cat.)

Again, I think this is nonsense; *please* do not try anything like this

at home. Some people have a reckless disregard for their (or their cat's)

probability measure.

Hope this hasn't given anyone unsafe ideas,

Nus

-- "If there are infinitely many goldfinches in the world, it seems that one cannot increase their total quantity by donating to the Audubon Society." -- Knobe/Olum/Vilenkin, "Philosophical Implications of Inflationary Cosmology" -- http://www.fastmail.fm - Choose from over 50 domains or use your own

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