Renormalization of Quantized GR

  • Thread starter waterfall
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  • #1
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Remember that the electroweak force couldn't be renormalized for over many decades, until Weinberg and company finally renormalized it when mass was introduced via the higgs mechanism. Right?

Now in the quantization of general relativity, we haven't been able to renormalize it after decades. What if one day, a method or mechanism would finally make it renormalizable. Would it automatically become the right theory of quantum gravity even without taking the strings and LQG path?
 

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  • #2
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I think introducing the Higgs mechanism is sorta like introducing strings. What's the difference between a string or lqg path and a new "method" or "mechanism"? Also, due to eg black hole entropy, it's pretty clear that at high energies gravity needs new degrees of freedom. So by itself it can never be renormalized, only treated as an EFT.
 
  • #3
tom.stoer
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What if one day, a method or mechanism would finally make it [general relativity] renormalizable. Would it automatically become the right theory of quantum gravity even without taking the strings and LQG path?
There seems to be such an approach, called asymptotic safety; the basic idea is to use non-perturbative methods b/c the theory may have a so-called non-Gaussian fixed point; asymptoptoc safety has been conjectured by Weinberg; you may be interested in a review

http://relativity.livingreviews.org/open?pubNo=lrr-2006-5&page=articlesu13.html [Broken]

You will also find some threads here in the "beyond forum" discussing these ideas.

Would it automatically become the right theory of quantum gravity even without taking the strings and LQG path?
Whether a theory is right or wrong does not only depend on mathematics but whether it agrees with nature. But yes - it could be that via this approach quantum gravity based on general relativity w/o loops or strings becomes be the right answer.
 
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  • #4
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There seems to be such an approach, called asymptotic safety; the basic idea is to use non-perturbative methods b/c the theory may have a so-called non-Gaussian fixed point; asymptoptoc safety has been conjectured by Weinberg; you may be interested in a review

http://relativity.livingreviews.org/open?pubNo=lrr-2006-5&page=articlesu13.html [Broken]

You will also find some threads here in the "beyond forum" discussing these ideas.


Whether a theory is right or wrong does not only depend on mathematics but whether it agrees with nature. But yes - it could be that via this approach quantum gravity based on general relativity w/o loops or strings becomes be the right answer.
They say that at very strong coupling, gravitons can self-interact and blow up (in the renormalization sense). What if one propose something akin to the higgs field that can tame the gravitons like wrapping them with some field that would prevent its self interactions?

Maybe strings theory and LQG were proposed to tame the gravitons self interactions from blowing up? Why not propose others that would be for the sole purpose of taming the gravitons?
 
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  • #5
tom.stoer
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Graviton self-interaction and Higgs have nothing to do with each other. A massive graviton would not only affect the self-interaction but especially the long distance behavior, i.e. we would not see a 1/r potential but an exponential decay!
 
  • #6
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Similar to the asymptotoc safety approach is the work of Kreimer. He is a pure high energy physicists and wrote a short note about this renormalization problem of gravity.

http://arxiv.org/abs/0705.3897
 
  • #7
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Graviton self-interaction and Higgs have nothing to do with each other. A massive graviton would not only affect the self-interaction but especially the long distance behavior, i.e. we would not see a 1/r potential but an exponential decay!
Of course I know enough particle physics to be aware gravitons don't feel the higgs force. What I was saying was "akin to higgs field". Do you know that Weinberg, Glashaw, Salam nearly abandoned the Electroweak theory if not for the arrival of the idea of Spontanteous Symmetry Breaking that produced the higgs field. So similarly, what if there was another scalar field like it whose function is to discretize or pixelize spacetime. I wonder if this can prevent the gravitons from self interacting destructively. Here one doesn't have to propose any strings or LQG. Is there such idea in the quantum gravity programme? Why not?
 

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