FearlessFerret

2005-06-10 06:21:52 UTC

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If String Theory is not background-free, and if it subsumes general relativity,Raw Message

how can the theory 'explain' space-time curvature?

/ff

Discussion:

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FearlessFerret

2005-06-10 06:21:52 UTC

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If String Theory is not background-free, and if it subsumes general relativity,Raw Message

how can the theory 'explain' space-time curvature?

/ff

R***@Lycos.com

2005-06-14 07:47:32 UTC

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In what sense do you mean explain? String theory replaces space-timeRaw Message

curvature with gravitons. I'm not sure how the rest works out, though.

R***@Lycos.com

2005-06-14 07:46:42 UTC

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Maybe spacetime is a large 3+1 brane. Or not. *Shrugs*Raw Message

Also, gr is just sr plus the equivilence principle. Plus you don't need

a special background, just an acceleration. The curvature in a specific

area can be gravitons messing with the particles. At least, that's how

one of my friends rationalizes it.

m***@yahoo.com

2005-06-14 07:50:07 UTC

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Raw Message

If String Theory is not background-free, and if it subsumes general relativity,

how can the theory 'explain' space-time curvature?

representable as the limit of manifolds that are Minkowski except on a

submanifold of measure 0.

The measure 0 subset is where the curvature is concentrated at and --

for 4-dimensions -- the singularities are in the most general case

characterized as 2-dimensional. If timelike and compact, they will be

string singularities.

Associated with each singularity is a set of loop invariants that

essentially define the Riemannian tensor as a singular delta-like

function equal to 0 off the source, with loop integrals that give you

non-zero curvature when linking the source.

Thus, you can have your cake and eat it too -- a theory that is

simultaneously strings and loops; simultaneously background-free and

Minkowski background.

This appears the classical level in string theory, where the solution

to the classical 2-dimensional singularity in an otherwise Minkowski

background is a 2-surface closely associated with a lightlike helical

worldline -- i.e., the worldline of a relativistic particle.

This also appears on the classical level in a very closely related

vein, where fermions, themselves, are directly representable as string

singularities:

Kerr-Newman Solution as a Dirac Particle

hep-th/0210103v2

2004 January 19

Arcos and Pereira

(From the abstract)

"For [source mass m, angular momentum a, electric charge q, where m^2 <

a^2 + q^2], the Kerr-Newmann solution of Einstein's equatins reduces to

a naked singularity of circular shape, enclosing a disk across which

the metric components fail to be smooth [which the paper goes on to

describe as a 'looking glass' type wormhole entrance]. By considering

the Hawking and Ellis extended interpretation of the extended

Kerr-Newman spacetime [the looking glass], it is show that, similarly

to the electron-positron system, the solution represents four

inequivalent states. Next, it is shown that due to the topological

structure of the extended Kerr-Newman spacetime, it does admit states

with half-integral angular momentum. This last fact is corroborated by

the fact that, under a rotation of space coordinates, these states

transform into themselves only after a [720 degree] rotation [as is

characteristic of spin 1/2 particles]. As a consequence it becomes

possible to naturally represent them in a Lorentz spinor basis. The

state vector representing the whole Kerr-Newman solution is then

constructed [i.e. the Dirac spinor, itself], and the evolution is shown

to be governed by the Dirac equation. The Kerr-Newman solution can

thus be consistently interpreted as a model for the electron-positron

system, in which the concepts of mass, charge and angular momentum

becomes connected with the spacetime geometry. Some phenomenological

consequences of the model are explored.

FearlessFerret

2005-06-21 07:25:44 UTC

Permalink

Raw Message

If String Theory is not background-free, and if it subsumes general relativity,

how can the theory 'explain' space-time curvature?

representable as the limit of manifolds that are Minkowski except on a

submanifold of measure 0.

sentence. After I've made my millions in software I'm going to retire and go

learn all this stuff. Either that or train full time for a 6th degree Black

Belt in Tae Kwon Do, I haven't decided.

Thanks for trying, though.

/ff

(I probably have a better chance with the babes in post-grad physics, and

there's less attendant risk of grave physical impairment.)

The measure 0 subset is where the curvature is concentrated at and --

for 4-dimensions -- the singularities are in the most general case

characterized as 2-dimensional. If timelike and compact, they will be

string singularities.

Associated with each singularity is a set of loop invariants that

essentially define the Riemannian tensor as a singular delta-like

function equal to 0 off the source, with loop integrals that give you

non-zero curvature when linking the source.

Thus, you can have your cake and eat it too -- a theory that is

simultaneously strings and loops; simultaneously background-free and

Minkowski background.

This appears the classical level in string theory, where the solution

to the classical 2-dimensional singularity in an otherwise Minkowski

background is a 2-surface closely associated with a lightlike helical

worldline -- i.e., the worldline of a relativistic particle.

This also appears on the classical level in a very closely related

vein, where fermions, themselves, are directly representable as string

Kerr-Newman Solution as a Dirac Particle

hep-th/0210103v2

2004 January 19

Arcos and Pereira

(From the abstract)

"For [source mass m, angular momentum a, electric charge q, where m^2 <

a^2 + q^2], the Kerr-Newmann solution of Einstein's equatins reduces to

a naked singularity of circular shape, enclosing a disk across which

the metric components fail to be smooth [which the paper goes on to

describe as a 'looking glass' type wormhole entrance]. By considering

the Hawking and Ellis extended interpretation of the extended

Kerr-Newman spacetime [the looking glass], it is show that, similarly

to the electron-positron system, the solution represents four

inequivalent states. Next, it is shown that due to the topological

structure of the extended Kerr-Newman spacetime, it does admit states

with half-integral angular momentum. This last fact is corroborated by

the fact that, under a rotation of space coordinates, these states

transform into themselves only after a [720 degree] rotation [as is

characteristic of spin 1/2 particles]. As a consequence it becomes

possible to naturally represent them in a Lorentz spinor basis. The

state vector representing the whole Kerr-Newman solution is then

constructed [i.e. the Dirac spinor, itself], and the evolution is shown

to be governed by the Dirac equation. The Kerr-Newman solution can

thus be consistently interpreted as a model for the electron-positron

system, in which the concepts of mass, charge and angular momentum

becomes connected with the spacetime geometry. Some phenomenological

consequences of the model are explored.

--

If virtual memory did not exist, it would be necessary for us to invent it.

If virtual memory did not exist, it would be necessary for us to invent it.

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