Re: Fw: NYT (Op-Ed) on Multiverse Theory

From: Hal Finney <>
Date: Wed, 16 Apr 2003 13:44:18 -0700

John Mikes writes:
> BTW (pardon me the scepticism) is the Multiverse less fictional? Even
> the logical argument of Deutsch seems a speculation-loaded 'evidence'.
> It requires the belief in a wide series of physical concepts, many of
> them only consequences of prior circumstantial explanations (like:
> "it has got to be"). I "believe" in sort of a 'multiverse' (note:
> 'believe'), yet not a bunch of universes similar to ours. I see no
> necessity that nature be bound to our schema of the anthropocentrically
> derived one feeble description of our universe.

What do you think of Tegmark's concepts for four "levels" of multiverse
as described at

(BTW I just got my copy of Scientific American yesterday and the cover
is really cool. "Infinite Earths in PARALLEL UNIVERSES Really Exist",
the text reads, with a painting of the Earth-Moon system surrounded by a
bubble of stars and galaxies, replicated infinitely off into the distance.
You can see a small picture at

Tegmark's four levels are:

1. In a spatially infinite universe, there should be infinitely many copies
of ourselves, our planet, and indeed the entire bubble of the universe that
we are able to see.

2. In the cosmological model of "inflation", there are an infinite number
of regions of space where the inflation has stopped, each separate from
the others, possibly with different dimensionalities and laws of physics.

3. In the many-worlds interpretation of quantum mechanics, the universe is
constantly splitting into causally disconnected branches, and we go on
living in each one.

4. If everything exists, or at least all mathematical objects or all
computer programs, then we and the universe would exist as a subset of
those collections, in all possible variations.

I think the point is that unless you disbelieve all of these, you are
forced in any case to deal with the philosophical implications of parallel
worlds, that you do in fact have an infinite number of duplicates.
And since much of the resistance to the more advanced levels 3 and 4
comes from concerns over these issues, that should eliminate resistance
founded on those worries.

Of course logically these are all pretty much independent, and it
is possible that 1 and 3 are right, 2 and 4 are wrong, or any other
combination. So you can consistently believe and disbelieve as you

Hal Finney
Received on Wed Apr 16 2003 - 16:46:43 PDT

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