Sentences with phrase «quantum gravity»
Quantum gravity is a concept that tries to combine two fundamental theories of physics: quantum mechanics (which explains how really small things behave) and general relativity (which describes gravity). It suggests that at incredibly small scales, like those found at the center of a black hole or during the Big Bang, gravity interacts with other forces in a quantum way. It aims to provide a better understanding of how gravity works in situations where it becomes extremely strong and complicated. Full definition
One reason for this reaction is that a complete theory of quantum gravity does not yet exist.
newscientist.com
The main challenge now is to combine the two ideas into one overarching theory, to be known as quantum gravity.
He and other quantum gravity theorists are pretty excited by that possibility, which just goes to show what they're up against.
With quantum gravity, however, this becomes unnecessary.
Indeed, many feel that information loss is the most pressing obstacle in understanding quantum gravity.
The most popular quantum gravity theory says that particles and forces arise from the vibrations of tiny loops — or strings — just 10 - 35 metres long.
This has allowed researchers from these disciplines to attack quantum gravity with a whole array of fresh concepts and mathematical tools.
It not only provides a step towards quantum gravity but also leads to an alternative picture of the universe.
The quest for the theory of quantum gravity is arguably the biggest challenge facing modern physics.
Body of work: Works on loop quantum gravity, which says abstract loops compose matter and space.
Scientists are looking for a so called «grand unified theory» that joins the two, known as quantum gravity.
In 1980 Alexei Starobinsky independently postulated a similar early phase of exponential expansion, in this case driven by quantum gravity effects.
«It is not possible to explain theories of quantum gravity at a level which a biologist could criticise,» he says.
And it has explained in certain very special cases the entropy of black holes, which is a big problem in quantum gravity.
Fortunately for quantum gravity theorists, the bartenders of the world are a patient group.
Loop quantum gravity moves in the opposite direction.
Until much more is known about quantum gravity and wormholes, virtual - reality machines and multiple universes, I'll do my time traveling through the chronology projector of the mind.
«He stands out as the soft - voiced English gentleman who makes deep points about gravity that nobody else has considered,» says Olaf Dreyer, an expert on quantum gravity at the Sapienza University of Rome.
The trick, say the researchers, is to replace Newtonian gravity with a theory called quantum gravity.
Physicists have had trouble developing a theory of quantum gravity because compared with the universe's other three forces — strong, weak and electromagnetism — gravity is pathetically feeble.
One candidate for such a unified quantum gravity model is string theory, which might describe the singularity as a fuzzy tangle of tiny vibrating strings.
«If quantum gravity in a flat space allows for a holographic description by a standard quantum theory, then there must be physical quantities, which can be calculated in both theories — and the results must agree,» says Grumiller.
«We are into the mysterious domain of quantum gravity where no theory yet exists to tell us what to expect.»
Jan Ambjørn of the Niels Bohr Institute at the University of Copenhagen and his colleagues have been using computer simulations to model quantum gravity based on spacetimes built from self - organizing «motes» that fall into place naturally.
Lee Smolin of the Perimeter Institute for Theoretical Physics noted that some forms of quantum gravity predict certain asymmetries — one direction of polarization might be favored over another — that could be imprinted in the cosmic microwave background (CMB), a faint echo of radiation from the early universe.
This would be quantum gravity written across the sky.
The quest for a theory of quantum gravity gained added significance after the recent discovery of ripples in spacetime dating back to a mere 10 - 36 seconds after the birth of the universe (SN: 4/5/14, p. 6).
«Of course I knew a relativistic version of MOND was needed,» he says, «but, hey, there is no theory of quantum gravity yet either.
«As for today, one could perhaps talk about a new «quantum gravity era» of tensor networks that is just starting,» he writes.
For example, loop quantum gravity preserves his discovery that space and time have no fixed background, and it also provides an answer to Einstein's questions of how to go beyond the continuum.
Some theories of quantum gravity require space - time itself to be grainy — to be made up of discrete quanta, presumably around 10 - 35 of a meter across because that's the scale at which Einstein's field equations generate their bothersome infinities.
A new approach to the decades - old problem of quantum gravity goes back to basics and shows how the building blocks of space and time pull themselves together
John Schwarz of Caltech showed that string theory could describe quantum gravity, launching the first superstring revolution in 1984.
Giovanni Amelino - Camelia, who studies quantum gravity at Sapienza University of Rome, Italy, is thrilled with the quality of observations and the analyses carried out by Laurent's group.
So quantum gravity, of which string theory is an example, is distant from experiment, and we have to live with that fact.
No wonder cynics have dismissed quantum gravity as little more than a parlour game.
For now, the much - vaunted superstring theory of quantum gravity looks safe.
He has shown that available technology — sensitive laser devices known as gravitational wave interferometers — can be used to test some rival quantum gravity theories.
The solution, Hoava says, is to snip threads that bind time to space at very high energies, such as those found in the early universe where quantum gravity rules.
In this week's Nature (vol 398, p 216), Amelino - Camelia works out the expected size of this noise for various quantum gravity theories.
Together with Arjun Bagchi, Rudranil Basu and Max Riegler, Daniel Grumiller managed to show that this entropy of entanglement takes the same value in flat quantum gravity and in a low dimension quantum field theory.
«We like them because they are at the frontier of what is possible in loop quantum gravity today — a bit more complicated than the cosmologies that have been studied over the last decade, but not so complicated as to become intractable.