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pirillo science forum beginner
Joined: 02 May 2005
Posts: 5

Posted: Thu May 12, 2005 5:46 am Post subject:
Re: Size of strings compared to size of elementary particles



Quote:  You want to average that over space _and_ time to get the rms size of
the string. I seem to recall that this is discussed in the references
that I provided.

Oh, so you do sort of a " average size for the whole history"
operator which say first computes the average distance from cm at each
time and then averages this over the whole history.
Hmmm?
I thought in curved backgrounds you did this at one instant
and found that the string became larger as time passed.
Or, were you saying more like there's an external parameter
which labels a family of spacetimes (the string lives in)
and as you vary this parameter, the quantity you described
above varies, although if one changes the target space,
then one changes the states. 

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Urs Schreiber science forum Guru Wannabe
Joined: 04 May 2005
Posts: 127

Posted: Thu May 12, 2005 6:33 am Post subject:
Re: Size of strings compared to size of elementary particles



"pirillo" <ultraman2002@hotmail.com> schrieb im Newsbeitrag
news:1115858009.327557.225680@z14g2000cwz.googlegroups.com...
Quote:  You want to average that over space _and_ time to get the rms size of
the string. I seem to recall that this is discussed in the references
that I provided.
Oh, so you do sort of a " average size for the whole history"
operator which say first computes the average distance from cm at each
time and then averages this over the whole history.
Hmmm?

I am sorry, but I have a hard time understanding what you are confused
about.
The idea we are talking about is not particular to string theory at
all but seems to be just a matter of common sense: You have some fluctuating
something and want to get an idea of its rough size. So you average the
distance of all its points from its center of mass and, since its
fluctuating, average these distances over some period of time. If that piece
of something is systematically growing or shrinking on larger time scales
you will want to take the time average over an interval which is large
enough compared to the fluctuations but small enough to be local in time
with respect to the longterm behaviour.
To be frank, I feel that the discussion of this point is getting a little
offtopic for sci.physics.strings. 

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pirillo science forum beginner
Joined: 02 May 2005
Posts: 5

Posted: Tue May 17, 2005 6:11 am Post subject:
Re: Size of strings compared to size of elementary particles



Quote:  you will want to take the time average over an interval which is
large enough compared to the fluctuations but small enough to be local
in time with respect to the longterm behaviour.

Yeah, but you said integrate over the "whole" world sheet
not over a "short time band" on the worldsheet. So you're averaging
over the "whole" infinite history. I'm just saying what you seemed to
say  not what you meant. Which I now think is to integrate over a small
time band.
Quote:  To be frank, I feel that the discussion of this point is getting a
little offtopic for sci.physics.strings.

And questions about Gerbes, Calabi Yau manifolds and all these objects
which are purely mathematical are not! Ha
I think this "is" very stringy! 

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mihai cartoaje science forum beginner
Joined: 29 May 2005
Posts: 10

Posted: Sun May 29, 2005 6:03 pm Post subject:
Re: Dirac operators on Lorentzian manifolds



i have written:
Quote:  j = Psi^h gamma^0 gamma^a Psi eta_ab w^b
which has *d*j = 0.

This is not always true from the construction.
Actually,
j = Psi^h gamma^0 gamma^a Psi eta_ab w^b
= j^b w_b
has the divergence *d*j = j^b w^a(v_a, v_b).
FAIK, it might work to find a coordinate
system in which w = sqrt( eta g ) has the
property v_a . w^a = 0. At first order,
a solution exists iff R = 0 + O(h^2). 

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Puppet_Sock science forum Guru Wannabe
Joined: 17 May 2005
Posts: 124

Posted: Mon Jun 06, 2005 9:41 pm Post subject:
Re: From Magnetic Monopole to Magnetic Strings



Golden Boar wrote:
Quote:  I made a huge mistake here, a positive magnetic monopole would
annihilate with a negatice magnetic monopole, so no magnetic strings
would be formed.

Not necessarily. Monopoles can have electric and topological
charge. There's a name for it objects with both, but I don't
recall it just off. Both values need to be coserved.
You should get a review article or two before you continue.
Socks 

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zitterbewegung@gmail.com1 science forum beginner
Joined: 24 May 2006
Posts: 8

Posted: Thu Jun 08, 2006 2:24 am Post subject:
Hybrid Manifold



Abstract: [Moderator's note: no responsibility for content. LM]
This is an attempt to define a bulk which corresponds to both a string
cosmological and brane cosmological formalism which disallows other
branes that exist outside this universe.
Our bulk is homogenous manifold similar to a Joyce manifold but this
then glued at every point to an AdS4 which forms a surface to the
manifold . This manifold forms the background of everything that
exists.
Definition of the Hybrid Manifold
We define our bulk as continuous map of all points on a AdS4 (which may
or may be periodic) manifold and the Joyce manifold.
We state that the observation of the propagation of point particles is
actually a reflection of the current shape of the Joyce manifold. On
our manifold when the Joyce manifold bends or is warped then the AdS4
manifold's characteristics change as a result of the continuous
mapping. In other words the AdS4 manifold shows the shape of the
underlying substructure of the Joyce manifold. The Joyce manifold is
bound to a certain set of shapes and transformations which must follow
the laws of physics in the AdS4.
But now we must extend the hybrid manifold to have properties that
reflect current physical observations. We must have a manifold that is
both restricted to a subset of shapes that can exist on the manifold.
Also we must deal with the fact that energy is quantized.
A quantization of energy using hybrid manifolds
As a string moves through the part of our manifold that consists of the
G2 manifold it bends the manifold slightly so that we can detect the
point particle on the AdS4 space. The surface of our new manifold is
glued and because of this it can reflect properties of its bending The
reason we can detect different messenger particles is because as a
string moves through our hybrid manifold it is bound at certain parts
of the hybrid manifold due to the structure of the manifold. There are
only a specific set of path's that the string can move through and that
determines how the surface is bent.
Another property is that due to quantization the vibrations of the
string follow an ascending or descending chain of vibrational patters
as the strings gain or lose energy. Therefore each string follows a set
of vibrations given a specific amount of energy that a string
possesses.
Disallowing Violations of the Laws of Physics
Certain properties of physics can be disallowed by the Joyce Manifold
being unable to transform to that state because it is impossible.
Certain holes that may occur may require a great deal of energy which
are prohibitive to accomplish because they require a great deal of mass
, energy, or mass/energy density. Therefore they would be difficult or
maybe even impossible to accomplish.
Gravity Representation
There are two ways to represent gravity using this hybrid space. One
way is to give it a formal messenger particle and have a given energy
value for it. Another method is to say that gravity is a result of the
specific shape of the Joyce manifold and requires no messenger particle
whatsoever. This representation will be chosen once we have direct
evidence for either outcome and may remain independent of the theory.
Conjectures
An interesting conclusion that we can get from this formalism is that
we don't need a set of interacting branes to start the process of the
formation of the universe. Instead some event must create a difference
inside of the space and make it form into a stable state. Therefore we
can confine the universe formation to just this brane.
Another conclusion we might be able to draw is that the underlieing
substructure allows for the space to be improbablly flat and bypasses
all horizons by being glued to a singular space that influences all
spacetime. That it is merely a propery of the substructure and
independant of an alternate form of matter. 

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zitterbewegung@gmail.com1 science forum beginner
Joined: 24 May 2006
Posts: 8

Posted: Thu Jun 08, 2006 2:25 am Post subject:
Rewrite of my assumptions. Was: Mistakes (again)



[Moderator's note: no responsibility for the content. LM]
This is an attempt to define a bulk which corresponds to both a string
cosmological and brane cosmological formalism which disallows other
branes that exist outside this universe.
Our bulk is homogenous manifold similar to a Joyce manifold but this
then glued at every point to an AdS4 which forms a surface to the
manifold . This manifold forms the background of everything that
exists. This bulk exists
Definition of the Hybrid Manifold
We define our bulk as continuous map of all points on a AdS4 (which may
or may be periodic) manifold and the Joyce manifold.
We state that the observation of the propagation of point particles is
actually a reflection of the current shape of the Joyce manifold. On
our manifold when the Joyce manifold bends or is warped then the AdS4
manifold's characteristics change as a result of the continuous
mapping. In other words the AdS4 manifold shows the shape of the
underlying substructure of the Joyce manifold. The Joyce manifold is
bound to a certain set of shapes and transformations which must follow
the laws of physics in the AdS4.
But now we must extend the hybrid manifold to have properties that
reflect current physical observations. We must have a manifold that is
both restricted to a subset of shapes that can exist on the manifold.
Also we must deal with the fact that energy is quantized.
A quantization of energy using hybrid manifolds
As a string moves through the part of our manifold that consists of the
G2 manifold it bends the manifold slightly so that we can detect the
point particle on the AdS4 space. The surface of our new manifold is
glued and because of this it can reflect properties of its bending The
reason we can detect different messenger particles is because as a
string moves through our hybrid manifold it is bound at certain parts
of the hybrid manifold due to the structure of the manifold. There are
only a specific set of path's that the string can move through and that
determines how the surface is bent.
Another property is that due to quantization the vibrations of the
string follow an ascending or descending chain of vibrational patters
as the strings gain or lose energy. Therefore each string follows a set
of vibrations given a specific amount of energy that a string
possesses.
Disallowing Violations of the Laws of Physics
Certain properties of physics can be disallowed by the Joyce Manifold
being unable to transform to that state ; because to do so would change
the topology of the space so greatly that the energy required would be
enormous.
Gravity Representation
There are two ways to represent gravity using this hybrid space. One
way is to give it a formal messenger particle and have a given energy
value for it. Another method is to say that gravity is a result of the
specific shape of the Joyce manifold and requires no messenger particle
whatsoever. This representation will be chosen once we have direct
evidence for either outcome and may remain independent of the theory. 

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zitterbewegung@gmail.com1 science forum beginner
Joined: 24 May 2006
Posts: 8


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