Loop quantum gravity Loop quantum gravity In theoretical physics, Ashtekar (new) variables (named after Abhay Ashtekar who invented them) represent an unusual way to rewrite the metric on the three-dimensional spatial slices in terms of a SU(2) gauge field and its complementary variable. Ashtekar variables are the key building block of loop quantum gravity. ...more on Wikipedia about "Ashtekar variables"
The Barrett-Crane model is a model in loop quantum gravity which was defined using the Plebanski action. ...more on Wikipedia about "Barrett-Crane model"
(Eplastopheme) Elastopheme is a physical phenomenon described by the theory of loop quantum gravity which specified the superposition of electrical fields and gravitational fields. ...more on Wikipedia about "Eplastopheme"
In loop quantum gravity, dynamics such as time-evolutions of fields are controlled by the Hamiltonian constraint. The identity of the Hamiltonian constraint is a major open question in quantum gravity, as is extracting of physical observables from any such specific constraint. ...more on Wikipedia about "Hamiltonian constraint"
General relativity is the theory of gravitation published by Albert Einstein in 1915. According to it, the force of gravity is a manifestation of the local geometry of spacetime. Mathematically, the theory is modelled after Riemann's metric geometry, but the Lorentz group of spacetime symmetries (an essential ingredient of Einstein's own theory of special relativity) replaces the group of rotational symmetries of space. Loop quantum gravity inherits this geometric interpretation of gravity, and posits that a quantum theory of gravity is fundamentally a quantum theory of spacetime. ...more on Wikipedia about "History of loop quantum gravity"
The Immirzi parameter (also known as the Barbero-Immirzi parameter) is a numerical coefficient appearing in loop quantum gravity, a nonperturbative theory of quantum gravity. The Immirzi parameter measures the size of the quantum of area in Planck units. As a result, its value is currently fixed by matching the semiclassical black hole entropy, as calculated by Stephen Hawking, and the counting of microstates in loop quantum gravity. ...more on Wikipedia about "Immirzi parameter"
(List of loop quantum gravity researchers) need to add affiliation and classify by subfield as far as possible ...more on Wikipedia about "List of loop quantum gravity researchers"
Loop quantum gravity (LQG), also known as loop gravity and quantum geometry, is a proposed quantum theory of spacetime which attempts to reconcile the seemingly incompatible theories of quantum mechanics and general relativity. This theory is one of a family of theories called canonical quantum gravity. It was developed in parallel with loop quantization, a rigorous framework for nonperturbative quantization of diffeomorphism-invariant gauge theory. In plain English this is a quantum theory of gravity in which the very space that all other physics occurs in is quantized. ...more on Wikipedia about "Loop quantum gravity"
Loop quantum gravity (LQG) is a quantization of a classical Lagrangian field theory. It is equivalent to the usual Einstein-Cartan theory in that it leads to the same equations of motion describing general relativity with torsion. As such, it can be argued that LQG respects local Lorentz invariance. Global Lorentz invariance is broken in LQG just like it is broken in general relativity (unless one is dealing with Minkowski spacetime, which is one particular solution of the Einstein field equations). On the other hand, there has been much talk about possible local and global violations of Lorentz invariance beyond those expected in straightforward general relativity. Of interest in this connection would be to see whether the LQG analogue of Minkowski spacetime breaks or preserves global Lorentz invariance, and Carlo Rovelli and coworkers have recently been investigating the Minkowski state of LQG using spin-foam techniques. ...more on Wikipedia about "Lorentz invariance in loop quantum gravity"
In physics, a spin foam is a four-dimensional graph made out of two-dimensional faces that represents one of the configurations that must be summed to obtain Feynman's path integral ( functional integration) describing the alternative formulation of quantum gravity known as loop gravity or loop quantum gravity. ...more on Wikipedia about "Spin foam"
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