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-   -   Manifold embedding (http://www.physicsforums.com/showthread.php?t=6550)

phoenixthoth Sep30-03 07:46 PM

manifold embedding
 
nash proved that any manifold can be embedded in R^3 in which the higher dimensional manifold gets crumpled and smoothness is lost.

is it possible that 11 dimensional space has already crumpled into our three dimensional universe and that wormholes exist precisely as a direct result of the crumpling?

cheers,
phoenix

Hurkyl Sep30-03 08:47 PM

http://www.wikipedia.org/wiki/Nash_embedding_theorem

The theorem says that any Riemann manifold can be (isometrically) embedded in Rn for some n. It doesn't say 3 specifically. In fact, n has to be at least as great as the dimension of the manifold.

phoenixthoth Sep30-03 09:00 PM

there was a big embedding theorem by nash, which is the one you're talking about, and a small embedding theorem, which is the one i'm talking about. it was mentioned in the "a beautiful mind," but i can't find the paper on the web.

cheers,
phoenix

phoenixthoth Oct5-03 01:33 AM

i did a little more research and found this quote from nash's autobiographical essay for winning the nobel:

So as it happened, as soon as I heard in conversation at M.I.T. about the question of the embeddability being open I began to study it. The first break led to a curious result about the embeddability being realizable in surprisingly low-dimensional ambient spaces provided that one would accept that the embedding would have only limited smoothness. And later, with "heavy analysis", the problem was solved in terms of embeddings with a more proper degree of smoothness.

so again i ask this: is it possible that the higher dimensional space has either fully or partially collapsed in the three dimensional space and that the nonsmoothness has resulted in wormholes?

Hurkyl Oct5-03 02:21 AM

I repeat, no. An n-dimensional manifold cannot be embedded in an m-dimensional manifold for m < n.

arivero Oct30-03 07:16 AM

a lot more
 
actually if you want a lorentzian metric in both manifold, the embedding rises, it needs a lot more of dimensions. About ninety or so, perhaps.

marcus Oct30-03 07:42 AM

Re: a lot more
 
Quote:

Originally posted by arivero
actually if you want a lorentzian metric in both manifold, the embedding rises, it needs a lot more of dimensions. About ninety or so, perhaps.
glad you are back, long time no see
I need to know the Cartan subgroup of SL(2,C)
(I am told there is just one and I suspect it is
the diagonal matrices but am not sure)

arivero Oct30-03 08:11 AM

Re: Re: a lot more
 
Quote:

Originally posted by marcus
glad you are back, long time no see
I need to know the Cartan subgroup of SL(2,C)
(I am told there is just one and I suspect it is
the diagonal matrices but am not sure)

Hi!

I am back just on a errand for nuclear data. I am afraid I can not confirm your guess -it seems a good one- without browsing across manuals :-( Two years teaching computer science and you see, one loses the training.

marcus Oct30-03 08:23 AM

In the Archive section of this forum I just posted what I think is the Weyl group of SL(2,C). These are new ideas for me, they seem nice

I think the normalizer of the (main) diagonal matrices in SL(2,C) consists of the union of the major and minor diagonal matrices

and then N(H)/H the Weyl group comes down to Z_2

which just flips the diagonal matrix to the other direction--major to minor and viceversa, but there is a minus sign in there too

you cant fool me, you have not gotten all that rusty by teaching computer science. it could even give you ideas


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