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Ambjorn Jurkiewicz Loll seem to have settled on what to call their new approach to Quantum Gravity.
In their most recent paper they consistently call the approach CDT, "Causal Dynamical Triangulations".
What I have to say first off about this is controversial and I might even have to take it back. I do think that Loop Gravity embodies a lot of valid physical intuition and has made impressive advances recently---removing important singularities, clarifying the origin of inflation, and so on (these are outlined in several excellent survey papers that have appeared recently)---but I think that Loop Gravity may actually be more complicated than a basic computable quantum gravity model needs to be.
The CDT approach has WORKED only just this year. It is comparatively elemental. The mathematics is comparatively concrete and rudimentary and it leads directly to computer models of dynamically changing space
(spacetime "path integrals" analgous to Feynm. path integrals for particle).
It has taken some 20 years to make this simple approach to gravity and quantum spacetime geometry work. It uses very basic, non-abstract, math-objects as tools, which makes it "clean" of unnecessary extra assumptions, and exceptionally free of fancy math. But basic-elementary does not seem to have meant that it was EASY for Ambjorn Jurkiewicz Loll to get it to work or that it is going to be easy to understand at first sight how.
My thought about the relation to Loop is that LQG has been a trailblazing thing and good platform for people to get intuition from and see results, but that CDT is more fundamental, assumes less structure, and there is probably a subterranean connection. LQG results may turn out to be derivable in the more spare context of CDT. Maybe even some equivalence theorems between the approaches. (as there was earlier linking different approaches to Quantum Electrodynamics)
Anyway, however it turns out---and everything is so preliminary one can only guess---it makes sense to identify the basic CDT papers. I'm offering this as a kind of minimal set. the three I have printed out and keep handy:
http://arxiv.org/hep-th/0105267
http://arxiv.org/hep-th/0404156
http://arxiv.org/hep-th/0411152
I will try to discuss just these three papers in this thread, and welcome any help anyone wants to give that focuses on these 3 basic CDT papers.
In their most recent paper they consistently call the approach CDT, "Causal Dynamical Triangulations".
What I have to say first off about this is controversial and I might even have to take it back. I do think that Loop Gravity embodies a lot of valid physical intuition and has made impressive advances recently---removing important singularities, clarifying the origin of inflation, and so on (these are outlined in several excellent survey papers that have appeared recently)---but I think that Loop Gravity may actually be more complicated than a basic computable quantum gravity model needs to be.
The CDT approach has WORKED only just this year. It is comparatively elemental. The mathematics is comparatively concrete and rudimentary and it leads directly to computer models of dynamically changing space
(spacetime "path integrals" analgous to Feynm. path integrals for particle).
It has taken some 20 years to make this simple approach to gravity and quantum spacetime geometry work. It uses very basic, non-abstract, math-objects as tools, which makes it "clean" of unnecessary extra assumptions, and exceptionally free of fancy math. But basic-elementary does not seem to have meant that it was EASY for Ambjorn Jurkiewicz Loll to get it to work or that it is going to be easy to understand at first sight how.
My thought about the relation to Loop is that LQG has been a trailblazing thing and good platform for people to get intuition from and see results, but that CDT is more fundamental, assumes less structure, and there is probably a subterranean connection. LQG results may turn out to be derivable in the more spare context of CDT. Maybe even some equivalence theorems between the approaches. (as there was earlier linking different approaches to Quantum Electrodynamics)
Anyway, however it turns out---and everything is so preliminary one can only guess---it makes sense to identify the basic CDT papers. I'm offering this as a kind of minimal set. the three I have printed out and keep handy:
http://arxiv.org/hep-th/0105267
http://arxiv.org/hep-th/0404156
http://arxiv.org/hep-th/0411152
I will try to discuss just these three papers in this thread, and welcome any help anyone wants to give that focuses on these 3 basic CDT papers.
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