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Author Topic: How is expanding spacetime described in string theory?  (Read 15807 times)

Offline LeeE

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How is expanding spacetime described in string theory?
« Reply #25 on: 12/12/2008 01:57:54 »
As nature abhors a vacuum, QM abhors zeros  :)

Which, for all it's cleverness, is what troubles me about QM.
 

Offline DoctorBeaver

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How is expanding spacetime described in string theory?
« Reply #26 on: 12/12/2008 12:28:27 »
Zeros & infinities
 

Offline LeeE

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How is expanding spacetime described in string theory?
« Reply #27 on: 12/12/2008 15:10:03 »
Oops - yes - and infinities too :)

But I'm more bothered by the zeros.
 

Offline DoctorBeaver

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How is expanding spacetime described in string theory?
« Reply #28 on: 12/12/2008 15:13:55 »
Especially in my bank account  :(
 

Offline yor_on

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How is expanding spacetime described in string theory?
« Reply #29 on: 13/12/2008 10:52:50 »

My argument is that this process of collapse will take some time and show some interesting and enlightening things before we reach the stage we cannot model using well understood processes. Also that if you then look at the structures you get from the point if view of the particles in them (not from outside) the results will be very revealing.

Basically you will get particles orbiting together with very high energies unaware of any gravitational field or gravitational gradient because they are in free fall but the energies of the particles are all very similar so the particles are essentially cold with respect to each other. Because of relativistic and gravitational distortion space has contracted and become one dimensional and time like while "time" has expanded to become multidimensional and space like.  As far as the particles are concerned this would look very much like a big bang with space expanding very uniformly and evenly without the need for mystic inflation.

Isn't this similar to a 'white hole' theory Soul Surfer?
But I like it:)

Although I can't quite see how a constant 'expansion' would come to bear?
As seen internally by observers?
 

Offline rustyw

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How is expanding spacetime described in string theory?
« Reply #30 on: 22/11/2009 04:31:53 »
Hi!

I'm Rusty Williamson, retired from IT industry and now into 3D animation/writing sci-fi.  I've been cramming on string theory for a book I'm working on... stumbled across this thread while researching M-Theory and had to sign up and jump in on a couple of issues.

String Theory literally predicts... well, everything!  Everything in general relativity, everything in quantum physics and... pretty much everything around us!  But... none of that counts.  We've surrounded a piece of the puzzle (which may or may not be string theory) from both the GR side and the quantum side and, in doing this, have predicted tons of things over the last 100 or so years.  Whether it be string theory or beach ball theory, when it comes to the last part of the theory of everything... there may not be too much left to predict and test (which falls within the scope of our capabilities)!  There are a dozen or so things that ST predicts that cannot be tested with current technology and if you look at these, if we could test them, they would have already been tested by GR or QP.  There are only two things I'm aware of that ST predicts that we can test but, neither will completely 'confirm' ST: there's the vanishing graviton that will be tested by CERN (this comes out of M-Theory and most Brane Theories); and, there's the flow characteristics of super hot and super cold liquids.

That's what I've gotten from my research anyway -- if anyone has news one either kindly post it.

My own humble prediction is that "the apparent weakness of gravity compared to the other forces dilemma" (e.g. missing gravity) will, via M-Theory, be tied soundly to the 'extra gravity' we see out there (currently called Dark Matter).  This relates to closed end, zero mass strings (i.e. gravitons) which can't 'hook on' to branes like other strings do.

I also have a very far out idea on what's behind Dark Energy but, I digress and, that's for another post lol.

Direct from sci-fi guy's armchair,
Rusty

 

Offline Mr. Scientist

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How is expanding spacetime described in string theory?
« Reply #31 on: 22/11/2009 05:30:05 »
I'm having trouble understanding what it means when the expansion of the universe is explained in terms of expanding spacetime.

One way to cure my confusion might be to approach the problem in terms of string theory which, as I understand it, supposes spacetime is quantized. In this framework, then, does the expansion of space result from:

a. The quanta are moving further apart. But, if so, what's in between them?

b. The quanta are packed together perfectly and nothing is between them -- they're getting bigger. But, if so, what's inside them, and how is it getting bigger? Seems to me this answer leads to a nested-dolls problem.

c. The quanta are packed perfectly, nothing is between them, and they aren't getting bigger. (Perhaps their size is dictated by a fundamental constant.) Instead, new quanta are "bubbling" into existence from nowhere, shouldering the existing quanta apart and thereby creating more space. This isn't forbidden because no matter or energy is being created. But, if this is happening, the reverse process should work too, so what's causing the asymmetry?

d. Something else I haven't thought of.

Because it expands from every point on the spacetime map.
 

Offline yor_on

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How is expanding spacetime described in string theory?
« Reply #32 on: 22/11/2009 16:34:49 »
Listen, when you're surrounded by German humour all day, you take it where you can...

Was?
 

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How is expanding spacetime described in string theory?
« Reply #32 on: 22/11/2009 16:34:49 »

 

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