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I have heard that loop quantum gravity is a "background independent" theory, in that there is no preferred coordinate system. Is LQG also a Machian theory?

- Thread starter quickAndLucky
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- #1

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I have heard that loop quantum gravity is a "background independent" theory, in that there is no preferred coordinate system. Is LQG also a Machian theory?

- #2

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LQG is based on GR, and GR is not a Machian theory, so LQG is not a Machian theory.

- #3

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If you swallow that then a look at the following papers may provide some insight into the OP:-

"Linking shape dynamics and loop quantum gravity"

L Smolin arXiv:1407.2909v1

"LOOP QUANTIZATION OF SHAPE DYNAMICS"

T Koslowski arXiv:1302.7037v1

- #4

haushofer

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Can you say that if the classical limit of LQG is still unknown? For string theory I'm pretty sure that it's not Machian as it reproduces GR plus stringy corrections and allows for the Minkowski vacuum, but for LQG I'm not sure.LQG is based on GR, and GR is not a Machian theory, so LQG is not a Machian theory.

- #5

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It is believed that classical limit of LQG is GR, but there is no rigorous proof. If one day someone proves the opposite, namely that certain precise formulation of LQG does not have GR as its classical limit, then this particular formulation of LQG will be abandoned and a different version of LQG will be called "the" LQG.Can you say that if the classical limit of LQG is still unknown?

Similarly to string theory, LQG is not a single uniquelly defined theory, but a broad and flexible theoretical framework.

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GR or Cartan-GR?It is believed that classical limit of LQG is GR

- #7

haushofer

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- #8

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I think this question is only relevant at points at which fermions are present:GR or Cartan-GR?

http://lanl.arxiv.org/abs/gr-qc/0505081