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Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics.It deals with environments in which neither gravitational nor quantum effects can be ignored, [1] such as in the vicinity of black holes or similar compact astrophysical objects, as well as in the early stages of the universe moments after the Big Bang.
The book's opening chapters trace the history and evolution of quantum gravity. Starting with pre-socratic philosopher Democritus through to the ideas of Sir Isaac Newton and, eventually, Albert Einstein, Rovelli puts forward a theory that quantum gravity brings great unity to the universe. Rovelli then states that space and time, waves and ...
(Later, loop quantum gravity inherited this geometric interpretation of gravity, and posits that a quantum theory of gravity is fundamentally a quantum theory of spacetime.) In the 1920s, the French mathematician Élie Cartan formulated Einstein's theory in the language of bundles and connections, [ 1 ] a generalization of Riemannian geometry ...
Theory of everything, or relativistic quantum gravity (c, G, h) Other cGh physics topics include Hawking radiation and black-hole thermodynamics . While there are several other physical constants, these three are given special consideration because they can be used to define all Planck units and thus all physical quantities. [ 6 ]
The problem of quantum cosmology is that the physical states that solve the constraints of canonical quantum gravity represent quantum states of the entire universe and as such exclude an outside observer, however an outside observer is a crucial element in most interpretations of quantum mechanics. [clarification needed]
1975 – Roberto Colella, Albert Overhauser, and Samuel Werner observe the quantum-mechanical phase shift of neutrons due to gravity. [195] Neutron interferometry was later used to test the principle of equivalence. [196] [197] [198] 1975 – Chandrasekhar and Steven Detweiler compute the effects of perturbations on a Schwarzschild black hole ...
While there are promising candidates for such a theory of quantum gravity, notably string theory and loop quantum gravity, there is at present no consistent and complete theory. It has long been hoped that a theory of quantum gravity would also eliminate another problematic feature of general relativity: the presence of spacetime singularities ...
One model, using loop quantum gravity, aims to explain the beginnings of the universe through a series of Big Bounces, in which quantum fluctuations cause the universe to expand. This use of loop quantum gravity also predicts a cyclic model of universes, with a new universe being created after an old one is destroyed, each with different ...