Physics duo suggest using early universe inflation as graviton detector

Oct 02, 2013 by Bob Yirka weblog
Image credit: Hubble/NASA

(Phys.org) —Physicists Lawrence Krauss and Frank Wilczek of Arizona State University and Australian National University, respectively, have uploaded a paper to the preprint server arXiv, in which they propose that it might be possible to establish the quantization of gravity by measuring the polarization of the Cosmic Microwave Background (CMB). Doing so they suggest, would provide a link between it and gravitational waves caused by inflation in the early universe.

Physicists, as most are aware, have been stymied in their efforts to discover a way to unify quantum mechanics and —most scientists in the field believe there is likely a gravity particle—they call it a graviton—that carries the force known as gravity. No one of course has ever seen one, or been able to prove it exists. This is because, they say, of how weak it is compared to the other forces, such as electromagnetism—to be able to see it, some have suggested, would require a device so massive that it would collapse in on itself into a black hole. For this reason, some researchers have suggested that we will never be able to see it. In their paper, Krauss and WIlczek suggest that it might not be necessary to see it, because there might be a way to infer its existence by measuring the CMB.

Their idea is that in the , just after the Big Bang, as inflation was occurring—gravitational waves should have been created which in turn would have caused photons present in the CMB to scatter in a certain pattern. Finding that pattern, they continue, would mean finding evidence of a particle that was carrying the gravitational force—the graviton. And if evidence for the existence of a graviton could be found, then physicists would finally have their universal theory. They add that they believe that dimensional analysis could provide a link between those early gravitational waves and Planck's constant, which is of course used in .

There are a couple of issues with the new theory—the first is that technology does not yet exist to measure the CMB in a way that would allow scientists to detect those early gravitational waves. Another is proving that any polarization found in the CMB can indeed be attributable to and not some other mechanism, force or process.

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More information: Using Cosmology to Establish the Quantization of Gravity, arXiv:1309.5343 [hep-th] arxiv.org/abs/1309.5343

Abstract
While many aspects of general relativity have been tested, and general principles of quantum dynamics demand its quantization, there is no direct evidence for that. It has been argued that development of detectors sensitive to individual gravitons is unlikely, and perhaps impossible. We argue here, however, that measurement of polarization of the Cosmic Microwave Background due to a long wavelength stochastic background of gravitational waves from Inflation in the Early Universe would firmly establish the quantization of gravity.

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User comments : 9

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AmritSorli
1 / 5 (18) Oct 02, 2013
They will not find gravitational waves, beasure they do not exist in the physical universe. Gravitational waves can not be produced by a stellar objects.....see articles of Prof. LOINGER on arxiv. Inertial mass, gravitatonal mass and gravity have origin in diminshed energy density of a 3D quantum vacuum.....see my latest book The Physics of Now - Amazon.
vacuum-mechanics
1 / 5 (17) Oct 02, 2013
While many aspects of general relativity have been tested, and general principles of quantum dynamics demand its quantization, there is no direct evidence for that. It has been argued that development of detectors sensitive to individual gravitons is unlikely, and perhaps impossible. We argue here, however, that measurement of polarization of the Cosmic Microwave Background due to a long wavelength stochastic background of from Inflation in the Early Universe would firmly establish the quantization of gravity.


This seems good, however the problem is that according to general relativity, vacuum space is empty without something to make the gravitational waves. Maybe this working physical mechanism could help….
http://www.vacuum...=7〈=en
hemitite
1.1 / 5 (12) Oct 02, 2013
If gravitons exist, then they would be virtually prescient as gravitational charge carriers between massive objects. If there was some way of screening out the electromagnetic forces involved in the Cashmere effect, then maybe one could detect gravity as a repulsive force given the negative vacuum energy thought to accompany this effect.
tadchem
1.5 / 5 (11) Oct 02, 2013
Gravitation is mathematically indistinguishable from a curvature in Minkowski space. Curvature is a continuous and differentiable function over the entire domain. Requiring gravitation to be quantizable makes it discontinuous and non-differentiable at points, an insurmountable incompatibility with the mathematics of GR.
tadchem
1.1 / 5 (10) Oct 02, 2013
The general principles of quantum dynamics demand quantization of gravity only because those principles are built on the assumption of a flat (Euclidean) space.
TheGhostofOtto1923
1 / 5 (3) Oct 02, 2013
Gravitation is mathematically indistinguishable from a curvature in Minkowski space. Curvature is a continuous and differentiable function over the entire domain. Requiring gravitation to be quantizable makes it discontinuous and non-differentiable at points, an insurmountable incompatibility with the mathematics of GR.
Couldnt you make a similar claim about any field?
Mr_Science
2.3 / 5 (15) Oct 02, 2013
WOW, 9 posts and only 1 that did not scream pseudoscience. At least they were all on topic. I guess a congrats is in order…..maybe
El_Nose
5 / 5 (5) Oct 02, 2013
Well they have already found two types of polarized light in CMB so I hope the effort is fruitful
Doc Brown
Oct 02, 2013
This comment has been removed by a moderator.
Torbjorn_Larsson_OM
4 / 5 (4) Oct 02, 2013
So 8-9 cranks, 2-3 rationals, and 1 crank supporter/crank sock puppet. :-/

@TGO, tadchem: Indeed, what works for QED works for QG. Gravitons are already made without quantizing problems as such, either by quantizing the GR Lagrangian (which only works for low energies/curvatures - but obeys relativity as per the usual needed consistency check) or making them in M theory (again, AFAIK obeys relativity).

The paper isn't about any problems with quantizing gravity but with observing the existing quanta.

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