Rewriting general relativity? Putting a new model of quantum gravity under the microscope

August 24, 2009
Rewriting general relativity?

Enlarge

Scientists are trying to figure out to what extent a new theory of quantum gravity will reproduce general relativity -- the theory that currently explains, to very high accuracy, how masses curve spacetime and create the influence of gravity. Credit: Image copyright American Physical Society, Illustration: Carin Cain

Does an exciting but controversial new model of quantum gravity reproduce Einstein's theory of general relativity? Scientists at Texas A&M University in the US explore this question in a paper appearing in Physical Review Letters and highlighted with a Viewpoint in the August 24th issue of Physics.

"If it ain't broke, don't fix it," sums up fairly well how many scientists have viewed Einstein's theory of general relativity. The theory, which Einstein developed in the early 20th century, says that matter curves spacetime, and it is this curvature which deflects massive bodies - an effect that we interpret as the influence of gravity. The theory has been tested to extremely high accuracy and without it, our satellite global positioning system would be off by about 10 km per day.

Despite the success of general relativity, one of the most important problems in modern physics is finding a theory of quantum gravity that reconciles the continuous nature of gravitational fields with the inherent 'graininess' of quantum mechanics. Recently, Petr Hořava at Lawrence Berkeley Lab proposed such a model for that has received widespread interest, in no small part because it is one of the few models that could be experimentally tested. In Hořava's model, Lorentz symmetry, which says that physics is the same regardless of the reference frame, is violated at small distance scales, but remerges over longer distance scales

The team at Texas A&M, which includes Hong Lu, Jianwei Mei and Christopher Pope, report their investigations into how the modifications proposed in Hořava's theory will broadly affect the solutions of general relativity. One aspect of their study is that it leads to an important caveat, described by Horatiu Nastase in a Viewpoint commentary in Physics. Lu et al.'s calculations, explains Nastase, suggest that Hořava's model only reproduces on unobservable scales, "larger than the size of the Universe".

Lu et al.'s paper is an important contribution to testing the Hořava model and shows that a good deal of work remains to understand its full implications.

More information: http://link.aps.org/doi/10.1103/PhysRevLett.103.091301; Download PDF (free)

Source: American Physical Society

4.2 /5 (17 votes)  

Filter


Move the slider to adjust rank threshold, so that you can hide some of the comments.


Display comments: newest first

OregonWind
Aug 24, 2009

Rank: 1 / 5 (1)
"Scientists at Texas A&M University in the US explore this question in a paper appearing in Physical Review Letters and highlighted with a Viewpoint in the August 24th issue of Physics."

Also

Division of Applied Mathematics and Theoretical Physics, China Institute for Advanced Study, Central University of Finance and Economics, Beijing, 100081, China


And

DAMTP, Centre for Mathematical Sciences, Cambridge University, Wilberforce Road, Cambridge CB3 OWA, United Kingdom

NeilFarbstein
Aug 24, 2009

Rank: 2.3 / 5 (4)
call it son of relativity...no..cousin of relativity.
HenisDov
Aug 25, 2009

Rank: 1 / 5 (7)
The Basic Implications Of E=Total[m(1 D)]
http://www.the-sc...age#3108
a recapitulation


A. Its essential statement

"Extrapolation of the expansion of the universe backwards in time to the early hot dense "Big Bang" phase, using general relativity, yields an infinite density and temperature at a finite time in the past. At age 10^-35 seconds the Universe begins with a cataclysm that generates space and time, as well as all the matter and energy the Universe will ever hold."

E = Energy content of the universe
m = mass content of the universe
D = distance, Total = in all spatial directions, from the point of Big-Bang, of singularity's energy-mass superposition

At D=0, E was = m and both E and m were, together, all the energy and matter the Universe will ever hold. Since the onset of the cataclysm, E remains constant and m diminishes as D increases.
The increase of D is the initial inflation, followed by the ongoing expansion, of what became the galactic clusters.

At 10^-35 seconds, D was already a fraction of a second above zero. This is when gravity starts. This is what started gravity. At this instance starts the energetic space texture, starts the straining of the space texture, and starts the space-texture-memory, gravity, that most probably will eventually overcome expansion and initiate re-impansion back to singularity.


B. Some of its further essential implications beyond Einstein-Hubble and re classical-quantum physics

And again and again : "On The Origin Of Origins"
http://www.the-sc...age#2753

1. It promotes commonsensical scientific critical thinking beyond Einstein-Hubble.

The universe is the archetype of quantum within classical physics, which is the fractal oneness of the universe.

Astronomically there are two physics. A classical Newtonian physics behaviour of and between galactic clusters, and a quantum physics behaviour WITHIN the galactic clusters.

The onset of big-bang's inflation, the cataclysmic resolution of the Original Superposition, started gravity, with formation - BY DISPERSION - of galactic clusters that behave as classical Newtonian bodies and continuously reconvert their original pre-inflation masses back to energy, thus fueling the galactic clusters expansion, and with endless quantum-within-classical intertwined evolutions WITHIN the clusters in attempt to delay-resist this reconversion.

2. There is no call, no need, for any dark energy. The energy of the universe is conserved. The mass of the universe is conserved in the form of energy, the energy fueling the clusters expansion. At the next universal singularity, at the next D = 0, there will again be E = m for a small fraction of a second...just wait and see...

Following Newton (1) gravity is decreased when mass is decreased and (2) acceleration of a body is given by dividing the force acting upon it by its mass. By plain common sense the combination of those two 'laws' may explain the accelerating cosmic expansion of galaxy clusters and the laws that drive it, based on the E/ m/ D relationship suggested above..

3. There is no call, no need, for a Higgs Particle.

The resolution of energy-mass superposition is reverted when D = 0. Shockingly sad, but must be soberingly faced rationally.


C. Its implications re the origin and nature of life beyond Darwin, re selection for survival

For Nature, Earth's biosphere is one of the many ways of temporarily constraining an amount of energy within a galaxy within a galactic cluster, for thus avoiding, as long as possible, spending this particularly constrained amount as part of the fuel that maintains the clusters expansion.

Genes are THE Earth's organisms and ALL other organisms are their temporary take-offs.

For Nature genes are genes are genes. None are more or less important than the others. Genes and their take-offs, all Earth organisms, are temporary energy packages and the more of them there are the more enhanced is the biosphere, Earth's life, Earth's temporary storage of constrained energy. This is the origin, the archetype, of selected modes of survival.

The early genes came into being by solar energy and lived a very long period solely on direct solar energy. Metabolic energy, the indirect exploitation of solar energy, evolved at a much later phase in the evolution of Earth's biosphere.


Dov Henis
(Comments from 22nd century)
Updated Life's Manifest May 2009
http://www.physfo...ic=14988&st=480&#entry412704
http://www.the-sc...age#2321
Slotin
Aug 25, 2009

Rank: 3.4 / 5 (5)
There are some objections concerning the Horava's model of gravity.

http://arxiv.org/abs/0905.2751
Alexa
Aug 27, 2009

Rank: 2.3 / 5 (3)
And here we can find good introduction into subject
http://physics.ap...es/v2/71
KBK
Sep 11, 2009

Rank: 1 / 5 (1)
Look up Einstein's Unified theory published in 1928. There you will find torsion tensors, ie Relativity thrown out and Maxwell's full equations put back in-right where they should be.

It was a successful, workable, and engineerable theory.

Which is why it was basically--erased.

It also appears as if Physorg is enacting a selected form of bias and premeditated crushing of opinions and thoughts they don't like. Ie, they have politicized the site. I am limited to 1000 characters. For example, there is a post in this comment area that far exceeds my own 'given' capacity.

This makes the political censoring quite obvious, does it not?

It makes you wonder who is running this site.

Obviously--someone does not like what I say. I'm not rude, I just bring up points in science they don't like to hear. I push at the dogma of science, as intelligent and thinking people should.

If they don't like what I say, then obviously--I'm saying the right things.

Think about it.
KBK
Sep 11, 2009

Rank: 3 / 5 (2)
The point being-is that the current dogma of science can and many times does pose a greater danger to the forward progress of man than religion.

Science flows from people, and there is nothing that intrinsically makes scientists less dogmatic than any given religious nutbar. This is basic psychology, 101. They just many a time.... hide it better.

Danger, Will Robinson, Danger.
Alizee
Sep 13, 2009

Rank: 1 / 5 (2)
We are facing supersymmetric "dark matter" phenomena here - scientists like internal observers of this evolution can get feeling, their universe of knowledge expands - but from perspective of surrounding society their approach becomed a brake of further evolution already.
vantomic
Oct 20, 2009

Rank: not rated yet
good call KBK, i see that HenisDov is allowed over 1000 words and he/she is spitting out pseudoscience (against the guidelines of physorg)...an explanation is in order physorg of why this person gets special treatment.
Rank 4.2 /5 (17 votes)
Relevant PhysicsForums posts
  • Conceptual issue with rolling sphere and friction.
    created1 hour ago
  • Conservation of momentum/energy
    created2 hours ago
  • Membrane Beam Transition Modelling Transition
    created5 hours ago
  • second law of thermodynamics
    created18 hours ago
  • Static Electric Orbiting of H2O Droplet to Knitting Needle
    created19 hours ago
  • Acousto optical modulators
    created20 hours ago
  • More from Physics Forums - Classical Physics

More news stories

Hovering not hard if you're top-heavy, researchers find

Top-heavy structures are more likely to maintain their balance while hovering in the air than are those that bear a lower center of gravity, researchers at New York University's Courant Institute of Mathematical Sciences ...

Physics / General Physics

created just added | popularity not rated yet | comments 0 | with audio podcast

SLAC, Stanford team focuses on high-energy electrons to treat cancer

Accelerator physicists at SLAC and cancer specialists from Stanford are working on a new technology that could dramatically reduce the time needed for cancer radiation treatments. The team ran an initial experiment ...

Physics / General Physics

created 3 hours ago | popularity not rated yet | comments 0

Measurements from high-energy collisions lead to better understanding of why meson particles disappear

For several years, physicists at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL), USA, have studied an unusual state of matter called the quark–gluon plasma, which they ...

Physics / General Physics

created 3 hours ago | popularity not rated yet | comments 0

Quantum physicist explains $100K offer for proof scaled-up quantum computing is impossible

(PhysOrg.com) -- MIT researcher Scott Aaronson has certainly riled the physics community with his offer this past Friday, of $100,000 to anyone who can prove that scaled-up quantum computing is impossible. ...

Physics / Quantum Physics

created Feb 08, 2012 | popularity 4.1 / 5 (11) | comments 32 | with audio podcast weblog

Explained: Sigma

It's a question that arises with virtually every major new finding in science or medicine: What makes a result reliable enough to be taken seriously? The answer has to do with statistical significance -- but ...

Physics / General Physics

created Feb 09, 2012 | popularity 5 / 5 (14) | comments 26


New understanding of DNA repair could eventually lead to cancer therapy

A research group in the Faculty of Medicine & Dentistry at the University of Alberta is hoping its latest discovery could one day be used to develop new therapies that target certain types of cancers.

Zuckerberg's focus drives Facebook's ascent

When Mark Zuckerberg showed up to rent Judy Fusco's Los Altos, Calif., house in the fall of 2004, soon after he'd arrived in Silicon Valley, the landlord was immediately struck by his confidence.

Both maternal and paternal age linked to autism

Older maternal and paternal age are jointly associated with having a child with autism, according to a recently published study led by researchers at The University of Texas Health Science Center at Houston (UTHealth).

Night, weekend delivery OK for babies with birth defects

Weekday delivery is no better than night or weekend delivery for infants with birth defects, according to a new study presented today at The Pregnancy Meeting, the Society for Maternal-Fetal Medicine's annual conference. ...

Sonic Cradle lands spot in TED exhibition

A Simon Fraser University graduate student project that melds music, meditation and modern technology has landed a rare spot as an exhibit at TEDActive 2012 in Palm Springs, California this month.

Drug halts organ damage in inflammatory genetic disorder

A new study shows that Kineret (anakinra), a medication approved for the treatment of rheumatoid arthritis, is effective in stopping the progression of organ damage in people with neonatal-onset multisystem inflammatory disease ...