Solution to the Cosmological Constant, Zero-Point Energy, and Quantum Gravity Problem

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  • #1
tom.stoer
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Has anybody studied this paper?

http://arxiv.org/abs/0909.0212v4
Comprehensive Solution to the Cosmological Constant, Zero-Point Energy, and Quantum Gravity Problems
Philip D. Mannheim
(Submitted on 1 Sep 2009 (v1), last revised 7 Jan 2010 (this version, v4))
Abstract: We present a solution to the cosmological constant, the zero-point energy, and the quantum gravity problems within a single comprehensive framework. We show that in quantum theories of gravity in which the zero-point energy density of the gravitational field is well-defined, the cosmological constant and zero-point energy problems solve each other by mutual cancellation between the cosmological constant and the matter and gravitational field zero-point energy densities. Because of this cancellation, regulation of the matter field zero-point energy density is not needed, and thus does not cause any trace anomaly to arise. We exhibit our results in two theories of gravity that are well-defined quantum-mechanically. Both of these theories are locally conformal invariant, quantum Einstein gravity in two dimensions and Weyl-tensor-based quantum conformal gravity in four dimensions (a fourth-order derivative quantum theory of the type that Bender and Mannheim have recently shown to be ghost-free and unitary). Central to our approach is the requirement that any and all departures of the geometry from Minkowski are to be brought about by quantum mechanics alone. Consequently, there have to be no fundamental classical fields, and all mass scales have to be generated by dynamical condensates. In such a situation the trace of the matter field energy-momentum tensor is zero, a constraint that obliges its cosmological constant and zero-point contributions to cancel each other identically, no matter how large they might be. Quantization of the gravitational field is caused by its coupling to quantized matter fields, with the gravitational field not needing any independent quantization of its own. With there being no a priori classical curvature, one does not have to make it compatible with quantization.
 

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  • #2
marcus
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In case anyone would like some background on the author:
http://www.phys.uconn.edu/people/faculty/storrs/mannheim/

I haven't looked at the 0909 paper you mentioned. But I do remember looking at this a couple of years ago.

http://arxiv.org/abs/0707.2283
Conformal Gravity Challenges String Theory
Philip D. Mannheim
(Submitted on 16 Jul 2007)
"The cosmological constant problem and the compatibility of gravity with quantum mechanics are the two most pressing problems in all of gravitational theory. While string theory nicely addresses the latter, it has so far failed to provide any compelling solution to the former. On the other hand, while conformal gravity nicely addresses the cosmological constant problem (by naturally quenching the amount by which the cosmological constant gravitates rather than by quenching the cosmological constant itself), the fourth order derivative conformal theory has long been thought to possess a ghost when quantized. However, it has recently been shown by Bender and Mannheim that not only do theories based on fourth order derivative equations of motion not have ghosts, they actually never had any to begin with, with the apparent presence of ghosts being due entirely to treating operators which were not Hermitian on the real axis as though they were. When this is taken care of via an underlying PT symmetry that such theories are found to possess, there are then no ghosts at all and the S-matrix is fully unitary. Conformal gravity is thus advanced as a fully consistent four-dimensional alternative to ten-dimensional string theory."
8 pages. Proceedings write-up of talk presented at PASCOS-07, Imperial College London, July 2007

Judging from the two abstracts, there seems to be some considerable overlap. I hesitate to comment.
 
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Here is a simple explanation of Mannheim's Conformal Gravity:
http://www.weeklyscientist.com/ws/articles/mannheim2.htm [Broken]

As for me , it is like a MOND correcting Newton law of gravity. Recent experiments shows Newton's law is exactly correct. Dark Matter effect is really a problem with a mass not with a Newton, I suppose.
 
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Here is a simple explanation of Mannheim's Conformal Gravity:
http://www.weeklyscientist.com/ws/articles/mannheim2.htm [Broken]

As for me , it is like a MOND correcting Newton law of gravity. Recent experiments shows Newton's law is exactly correct. Dark Matter effect is really a problem with a mass not with a Newton, I suppose.
Which experiments? My days are spent dreaming about such experiments but I've heard of no such results.
 
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experiments typically look for failures of the inverse-square law behavior of gravity in the laboratory. The most accurate tests over short distances have been performed by the Eöt-Wash group. A future satellite experiment, SEE (Satellite Energy Exchange), will search for fifth forces in space and should be able to further constrain violations of the strong equivalence principle. Other limits, looking for much longer-range forces, have been placed by searching for the Nordtvedt effect, a "polarization" of solar system orbits that would be caused by gravitational self-energy accelerating at a different rate from normal matter. This effect has been sensitively tested by the Lunar Laser Ranging Experiment. Other tests include studying the deflection of radiation from distant radio sources by the sun, which can be accurately measured by very long baseline interferometry. Another sensitive test comes from measurements of the frequency shift of signals to and from the Cassini spacecraft. Together, these measurements have put tight limits on Brans-Dicke theory and other alternative theories of gravity.
http://en.wikipedia.org/wiki/Equivalence_Principle

We perceive the force of gravity as a result of our being unable to follow the geodesics of spacetime, because the mechanical resistance of matter prevents us from doing so. This fistitious force is equal F=GMm/r^2 (Newton) as the above experiments shows.

General Relativity shows the motion due the geodesic but the gravitational interaction remains.
Dark Matter effect (acceleration due to mass) agrees with Newton and General relativity. There isn't a time dilation effect like a Mercury perihelion distortion.

It is my statement and may be I am not correct. So I would like to discuss it on my thread beneath - QLG and Cramer's TI.
 
  • #6
Wallace
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Reffering to the OP, I'm not sure (given the abstract, I haven't read the paper) that this solves the CC problem. It still doesn't explain why the CC has the value that it does, which is the problem given all the fine-tuning and co-incidence problems that this value implies.

Maybe I'm misreading the situation though, I know comparatively little about the 'physists' CC problem compared to the 'cosmologists' one.
 
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It still doesn't explain why the CC has the value that it does...

An even more serious problem is that this theory makes the kind of inflationary scenarios that are very nearly universally believed to be needed to solve so many problems in cosmology and particle physics impossible. Therefore either inflation isn`t needed or this theory has to be modified to produce inflation under the right circumstances. I don`t see how the latter could be achieved without gutting the basic ideas on which this theory is based.
 

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