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I was intrigued by this paper and the approach:
http://arxiv.org/abs/gr-qc/0611090
Cosmology as a search for overall equilibrium
Authors: Carlos Barcelo
Comments: 9 pages, 1 figure
"In this letter we will revise the steps followed by A. Einstein when he first wrote on cosmology from the point of view of the general theory of relativity. We will argue that his insightful line of thought leading to the introduction of the cosmological constant in the equations of motion has only one weakness: The constancy of the cosmological term, or what is the same, its independence of the matter content of the universe. Eliminating this feature, I will propose what I see as a simple and reasonable modification of the cosmological equations of motion. The solutions of the new cosmological equations give place to a cosmological model that tries to approach the Einstein static solution. This model shows very appealing features in terms of fitting current observations."
This builds upon earlier works in collaboration with Matt Visser on the concept of Analogue Gravity - an alternative to string and LQG approaches to quantum gravity. It is an interesting idea that, by all appearances, is more touchy feely [testable] than these approaches. It has some warts, mainly the inability to produce the expected quantum backreactions, but not yet mortally wounded so far as I can see.
The idea is substantially based on this also fascinating paper from 2001:
Einstein Gravity as an emergent phenomenon?
Authors: Carlos Barcelo, Matt Visser, Stefano Liberati
Comments: 8 pages, Essay awarded an honorable mention in the year 2001 Gravity Research Foundation essay competition
Journal-ref: Int.J.Mod.Phys. D10 (2001) 799-806
"In this essay we marshal evidence suggesting that Einstein gravity may be an emergent phenomenon, one that is not ``fundamental'' but rather is an almost automatic low-energy long-distance consequence of a wide class of theories. Specifically, the emergence of a curved spacetime ``effective Lorentzian geometry'' is a common generic result of linearizing a classical scalar field theory around some non-trivial background. This explains why so many different ``analog models'' of general relativity have recently been developed based on condensed matter physics; there is something more fundamental going on. Upon quantizing the linearized fluctuations around this background geometry, the one-loop effective action is guaranteed to contain a term proportional to the Einstein--Hilbert action of general relativity, suggesting that while classical physics is responsible for generating an ``effective geometry'', quantum physics can be argued to induce an ``effective dynamics''. This physical picture suggests that Einstein gravity is an emergent low-energy long-distance phenomenon that is insensitive to the details of the high-energy short-distance physics."
Some tantalizing related material has arisen in condensed matter physics along these lines. Perhaps there is an underlying 'apples to oranges' problem with existing approaches to quantum qravity.
http://arxiv.org/abs/gr-qc/0611090
Cosmology as a search for overall equilibrium
Authors: Carlos Barcelo
Comments: 9 pages, 1 figure
"In this letter we will revise the steps followed by A. Einstein when he first wrote on cosmology from the point of view of the general theory of relativity. We will argue that his insightful line of thought leading to the introduction of the cosmological constant in the equations of motion has only one weakness: The constancy of the cosmological term, or what is the same, its independence of the matter content of the universe. Eliminating this feature, I will propose what I see as a simple and reasonable modification of the cosmological equations of motion. The solutions of the new cosmological equations give place to a cosmological model that tries to approach the Einstein static solution. This model shows very appealing features in terms of fitting current observations."
This builds upon earlier works in collaboration with Matt Visser on the concept of Analogue Gravity - an alternative to string and LQG approaches to quantum gravity. It is an interesting idea that, by all appearances, is more touchy feely [testable] than these approaches. It has some warts, mainly the inability to produce the expected quantum backreactions, but not yet mortally wounded so far as I can see.
The idea is substantially based on this also fascinating paper from 2001:
Einstein Gravity as an emergent phenomenon?
Authors: Carlos Barcelo, Matt Visser, Stefano Liberati
Comments: 8 pages, Essay awarded an honorable mention in the year 2001 Gravity Research Foundation essay competition
Journal-ref: Int.J.Mod.Phys. D10 (2001) 799-806
"In this essay we marshal evidence suggesting that Einstein gravity may be an emergent phenomenon, one that is not ``fundamental'' but rather is an almost automatic low-energy long-distance consequence of a wide class of theories. Specifically, the emergence of a curved spacetime ``effective Lorentzian geometry'' is a common generic result of linearizing a classical scalar field theory around some non-trivial background. This explains why so many different ``analog models'' of general relativity have recently been developed based on condensed matter physics; there is something more fundamental going on. Upon quantizing the linearized fluctuations around this background geometry, the one-loop effective action is guaranteed to contain a term proportional to the Einstein--Hilbert action of general relativity, suggesting that while classical physics is responsible for generating an ``effective geometry'', quantum physics can be argued to induce an ``effective dynamics''. This physical picture suggests that Einstein gravity is an emergent low-energy long-distance phenomenon that is insensitive to the details of the high-energy short-distance physics."
Some tantalizing related material has arisen in condensed matter physics along these lines. Perhaps there is an underlying 'apples to oranges' problem with existing approaches to quantum qravity.