Re: Number of Dimensions at Level 2?

From: Hal Finney <hal.domain.name.hidden>
Date: Tue, 22 Apr 2003 16:11:35 -0700

Paul Hughes writes:
> So if I understnad you correctly this means that all
> other level 1 multiverses (of various constants) are
> 'reachable' within this 11 dimensional super-space of
> Level 2 without resorting to even higher dimensions
> beyond 11?

First, I was wrong, it's 10 dimensions, not 11. In his article Tegmark
says 9 dimensions, but I was also counting time and he wasn't.

As far as whether they are 'reachable', I can't answer that because I
don't know what you mean by 'reachable'. You are apparently using the
term figuratively as indicated by the quotes, but there is no telling
what you mean by that. None of the other level 2 universes are literally
reachable, we can't leave our own universe.

As I understand what Tegmark is saying, originally there was one universe
which was inflating, expanding exponentially fast. It had 10 dimensions
(9 spatial, 1 temporal). Over time, various parts of this universe
stopped inflating and sort of budded off, forming independent universes,
one of which is our own. In each of these sub-universes, spontaneous
symmetry breaking set a number of the physical parameters more or less
randomly. This includes the dimensionality, as well as various physical
parameters like field strengths and cosmological constants.

So I don't think it would be correct to think of the original
10-dimensional space as a super-space that includes this universe.
Rather, that space is in our past. Our universe is not embedded in a
higher dimensional structure. There is no space and no dimensionality
outside of the universes. Only within a universe is space and dimension
defined.

Hal Finney
Received on Tue Apr 22 2003 - 19:13:28 PDT