Quantum gravity

In theories of quantum gravity, the graviton is the hypothetical elementary particle that mediates the force of gravitational interaction. It is a quantum of gravitational wave energy. There is no complete quantum field theory of gravitons due to the unsolved mathematical problem of renormalization in general relativity. This problem is avoided in string theory, which has the graviton as a massless state of a fundamental string, but that theory has not made sufficient progress.

field of theoretical physics

set of units of measurement defined exclusively in terms of universal physical constants proposed by physicist Max Planck

fluctuation of spacetime on very small scales

duality between theories of gravity on anti-de Sitter space and conformal field theories

In supergravity theories combining general relativity and supersymmetry, the gravitino () is the gauge fermion supersymmetric partner of the hypothesized graviton. It has been suggested as a candidate for dark matter.

thumb|A diagram comparing the structure of a classical black hole with a gravastar.

attempts to develop a quantum mechanical theory of cosmology

mathematical theory in which noncommutative algebraic structures are interpreted as rings of functions on an abstract space

art of a theory that attempts to combine mathematically the ideas of quantum mechanics and general relativity

A chronon is a proposed quantum of time, that is, a discrete and indivisible "unit" of time as part of a hypothesis that proposes that time is not continuous. In simple language, a chronon is the smallest, discrete, non-decomposable unit of time.

nonsingular electromagnetic or gravitational wave held together in a confined region by the gravitational attraction of its own field energy

gravitational object composed of matter

theory of particle physics

locally finite partially ordered set, used to model discretized Lorentzian spacetime

scale

black holes appearing from quantum spacetime fluctuations

formulation of general relativity

physical theory in which there is not only a maximum velocity (as in special relativity), but also a maximum energy scale and minimum length scale

hypothetical phenomenon where an observer falling into a black hole encounters high-energy quanta at the event horizon

conceptual conflict between general relativity and quantum mechanics

theory that tries to give a quantum field description of gravity

thumb|Notional amplituhedron visualization In mathematics and theoretical physics (especially twistor string theory), an amplituhedron is a geometric structure introduced in 2013 by Nima Arkani-Hamed and Jaroslav Trnka. It enables simplified calculation of particle interactions in some quantum field theories. In planar N = 4 supersymmetric Yang–Mills theory, also equivalent to the perturbative topological B model string theory in twistor space, an amplituhedron is defined as a mathematical space known as the positive Grassmannian.

theory of quantum gravity

object composed of dark energy that outwardly resembles a black hole

conjencture unifying entanglement and wormholes

nonlinear modification of the Schrödinger equation

approximation to the theory of quantum gravity

physics model in which particles (except the graviton) are localized on a 4d brane inside a 5d anti-de Sitter space

anomalies that can arise in gauge theories coupled to gravity

fringe theory claiming to unify quantum mechanics and general relativity

set of mathematical concepts propagating geometric concepts

black hole solution in 2+1 dimensional topological gravity with a negative cosmological constant

conjecture that gravity must be the weakest force

Proposed model of gravity

interdisciplinary science program at Harvard University

constraints on possible particle properties

space of semiclassical field theories that cannot be consistently embedded in string theory

an equation in the Hamiltonian formulation of geometrodynamics

conjectured solution to the black hole information paradox