What Is The Quantum Loop Gravity Theory

What is the quantum loop gravity theory?

Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications.

What is the most promising theory of quantum gravity?

Physicists are mulling over a number of theories to solve this problem, but Zurek says that string theory remains the best description to date. Physicists originally proposed string theory in the late 1960s, and it can come in many different flavors.

What are the predictions of loop quantum gravity?

The most appealing aspect of loop quantum gravity is that it predicts that space is not infinitely divisible, but that it has a granular structure. The size of these elementary “quanta of space” can be computed explicitly within the the- ory, in an analogous way to the energy levels of the hydrogen atom.

Does loop quantum gravity predict the graviton?

The current main approaches to quantum gravity, such as string theory and loop quantum gravity, predict the existence of gravitons with the same properties we see in the simple “quantized wave” approach. Even if gravitons exist, it’s likely that we’d never be able to detect them.

Why is it called loop quantum gravity?

The word loop appears in the name because the theory’s foundation is based on a rewriting of Einstein’s general relativity in terms of lines (instead of points as it’s usually done). It doesn’t change any of the physics but makes some calculations easier, especially when it comes to quantizing space-time.

Who solved quantum gravity?

The current understanding of gravity is based on Albert Einstein’s general theory of relativity, which incorporates his theory of special relativity and deeply modifies the understanding of concepts like time and space.

What is the aim of quantum gravity?

So, in the meantime, theorists are rethinking the nature of the universe’s most fundamental elements. One theory, known as loop quantum gravity, aims to resolve the conflict between particles and space-time by breaking up space and time into little bits — an ultimate resolution beyond which no zooming can take place.

Why can’t we solve quantum gravity?

We don’t understand how to calculate gravity’s behavior at high energies, at small scales, near singularities, or when quantum particles exhibit their inherently quantum nature. Similarly, we don’t understand how the quantum field that underpins gravity — assuming there is one — behaves at all under any circumstances.

Who invented quantum gravity?

In 1935, when both quantum mechanics and Albert Einstein’s general theory of relativity were young, a little-known Soviet physicist named Matvei Bronstein, just 28 himself, made the first detailed study of the problem of reconciling the two in a quantum theory of gravity.

What math is needed for loop quantum gravity?

For loop quantum gravity, the most important background math needed is differential geometry, more specifically, the theory of connections on fiber bundles. For spin network theory, the most important math background is the theory of Lie groups, more specifically, the theory of covering groups of Lie groups.

What are the flaws of loop quantum gravity?

The biggest flaw in loop quantum gravity is that it has yet to successfully show that you can take a quantized space and extract a smooth space-time out of it.

What is the problem of time in loop quantum gravity?

Motivated by the Immirzi ambiguity in loop quantum gravity and the near conformal invariance of the standard model of elementary particles, Charles Wang and co-workers have argued that the problem of time may be related to an underlying scale invariance of gravity-matter systems.

What is the meaning of quantum gravity?

Quantum Gravity is the name given to any theory that describes gravity in the regimes where quantum effects cannot be disregarded.

What is the loop quantum gravity singularity?

Loop quantum gravity is believed to eliminate singularities such as the big bang and big crunch singularity. This belief is based on studies of so-called loop quantum cosmology which concerns symmetry-reduced models of quantum gravity.