New theory for Quantum Gravity
Posted: Sun Nov 29, 2009 10:53 pm
Could this be the beginning of greater understanding of Gravity?
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Did you not mean to say. Could this be the beginning of a greater understanding of everything?BMAONE23 wrote:Could this be the beginning of greater understanding of Gravity?
Could this be the beginning of a greater understanding of everything?mark swain wrote:be the beginning of greater understanding of Gravity?
An approach to a theory of quantum gravityPhysicists struggling to reconcile gravity with quantum mechanics have hailed a theory – inspired by pencil lead – that could make it all very simple
IT WAS a speech that changed the way we think of space and time. The year was 1908, and the German mathematician Hermann Minkowski had been trying to make sense of Albert Einstein's hot new idea - what we now know as special relativity - describing how things shrink as they move faster and time becomes distorted. "Henceforth space by itself and time by itself are doomed to fade into the mere shadows," Minkowski proclaimed, "and only a union of the two will preserve an independent reality."
And so space-time - the malleable fabric whose geometry can be changed by the gravity of stars, planets and matter - was born. It is a concept that has served us well, but if physicist Petr Hořava is right, it may be no more than a mirage. Hořava, who is at the University of California, Berkeley, wants to rip this fabric apart and set time and space free from one another in order to come up with a unified theory that reconciles the disparate worlds of quantum mechanics and gravity - one the most pressing challenges to modern physics.
Since Hořava published his work in January 2009, it has received an astonishing amount of attention. Already, more than 250 papers have been written about it. Some researchers have started using it to explain away the twin cosmological mysteries of dark matter and dark energy. Others are finding that black holes might not behave as we thought. If Hořava's idea is right, it could forever change our conception of space and time and lead us to a "theory of everything", applicable to all matter and the forces that act on it.
Quantum gravity at a Lifshitz point - P HořavaAt large distances, Einstein’s theory of general relativity describes gravitational physics remarkably well. However, attempts at defining quantum gravity at arbitrarily short distances based on the Einstein-Hilbert action of general relativity fail.
In two papers appearing in Physical Review Letters and Physical Review D, Petr Hořava of the University of California, Berkeley, in the US suggests a novel solution to finding a quantum theory of gravity that is renormalizable. The novelty of Hořava’s approach lies in temporarily abandoning the symmetries that are the cornerstone of general relativity: invariance under general space-time coordinate transformations. Hořava proposes a carefully constructed theory that treats time and space differently but has the virtue of short distance behavior compatible with renormalizability.
But how is this theory related to Einstein’s general relativity—our well-tested theory of gravity? According to Hořava, general relativity arises in the infrared (long distance) limit of his theory where the familiar properties and symmetries of general relativity emerge.
This too was proposed as simplicity itself not long ago on this forum.bystander wrote:Rethinking Einstein: The end of space-time
New Scientist | Physics and Math | 09 Aug 2010Physicists struggling to reconcile gravity with quantum mechanics have hailed a theory – inspired by pencil lead – that could make it all very simple
Hořava, who is at the University of California, Berkeley, wants to rip this fabric apart and set time and space free from one another ...
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