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excess of matter over anti-matter
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Alan
science forum addict


Joined: 03 May 2005
Posts: 51

PostPosted: Tue Apr 05, 2005 5:08 am    Post subject: excess of matter over anti-matter Reply with quote

Two more faq-type questions ...

I can visualize separated electrons and positrons,
with large 3D spatial separations, as possibly at the *ends* of strings,
where the strings themelves extend a Planck length into
other dimensions inaccessible to us. Analogies
from Flatland come to mind.
My mental picture is a mobius strip contructed in
the usual way from real paper with non-zero thickness.
I imagine the surface of the strip to be our accesible universe and the
thickness
of the paper is, say, a Planck length. A widely separated
electron and positron (from our normal perspective)
are then on opposite sides of the strip,
connected by a Planck length string running punching through the paper.

My first question:
Is string theory for electrons at all compatible with my simple mental
picture?

One problem with this simple picture that I can see is
the problem of the excess of matter over anti-matter.
It would seem that if matter is always at the end of strings,
then some of the open ends would have to be attached to inaccessible
dimensions.


Thus my second question:

Just what is the string theory take on the problem of the excess of matter?

regards,
alan
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Urs Schreiber
science forum Guru Wannabe


Joined: 04 May 2005
Posts: 127

PostPosted: Tue Apr 05, 2005 8:01 am    Post subject: Re: excess of matter over anti-matter Reply with quote

"Alan" <info@optioncity.REMOVETHIS.net> schrieb im Newsbeitrag
news:KqOdnWetZ7kDMszfRVn-2g@adelphia.com...

Quote:
Two more faq-type questions ...

Indeed. Once again I don't even try to give full faq entry answers. But
maybe it's a humble start.


Quote:
I can visualize separated electrons and positrons,
with large 3D spatial separations, as possibly at the *ends* of strings,


It makes good sense to visualize the ends of strings as a quarks, with the
string itself acting like a line of "color flux" between these quarks.
That's in fact one way how the string was originally conceived in field
theory.

However it should be noted that in phenomenological models that try to find
scenarios in string theory which yield the standard model particles at low
energies it's not string endpoints that become the quarks of the standard
model, but entire strings.


Quote:
My mental picture is a mobius strip contructed in

I don't see what the Moebius strip has to do here.


Quote:
Is string theory for electrons at all compatible with my simple mental
picture?

Not really, it seems to me.

I have once tried to give a rough description of how string states reproduce
particles and fermions in particular here:

http://golem.ph.utexas.edu/string/archives/000334.html .

Maybe that helps.


Quote:
Just what is the string theory take on the problem of the excess of
matter?

I am not good at phenomenology, but as far as I know this is dealt with
exactly as in the field theory models.
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Alan
science forum addict


Joined: 03 May 2005
Posts: 51

PostPosted: Tue Apr 05, 2005 2:09 pm    Post subject: Re: excess of matter over anti-matter Reply with quote

"Urs Schreiber" <Urs.Schreiber@uni-essen.de> wrote

Quote:
I have once tried to give a rough description of how string states
reproduce particles and fermions in particular here:

http://golem.ph.utexas.edu/string/archives/000334.html .


Thanks, Urs, that link was very helpful and showed me
how far off my visualization was from the actual theory.

Here's an unrelated question:

I am somewhat familar with regularization schemes for
perturbation expansions in field theory, such as dimensional regularization.
For example, say we have a conventional (point particle) field theory
whose Feynman diagrams are divergent in D dimensions, but
can be regularized in D + eps dimensions. Now this usually
interpretted as just a mathematical 'trick', since there are other
regularization
schemes that will work in the original D dimensions. Since it's
a trick, no physical reality is usually attached to the D + eps dimensions.
(The exception is Wilson's eps-expansion for condensed matter,
where one really does want to calculated something in the D' = D + eps
dimension).

Now string theory seems to smack a little of this in that the
theory is ill-defined in say 4D, but if we add an "eps extension" into
another
6D then all is ok-- in my vague understanding. Usually eps is
described as the Planck length, but I assume any arbitrarily
small number would also work. So, I wonder
is there is any sense to regarding the compact dimensions
and all that come with them as perhaps
merely a 'regularization' scheme for a unified theory that really
exists only in 4D?
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