Quantum cosmology
Quantum cosmology is the attempt in theoretical physics to develop a quantum theory of the Universe. This approach attempts to answer open questions of classical cosmology, particularly those related ...
Quantum cosmology - Wikipedia
A New ‘Einstein’ Equation Suggests Wormholes Hold Key To Quantum Gravity
A new Einsteinian equation, ER=EPR, may be the clue physicists need to merge quantum mechanics with general relativity.
Much Like White Light, Spacetime Is Also Composed Of A Certain Rainbow
When white light is passed through a prism, the rainbow on the other side reveals a rich palette of colors. Theorists from the Faculty of Physics, University of Warsaw have shown that in models of th...
What Happens If You Fall Into A Black Hole?
Quanta Magazine’s new In Theory video series, featuring David Kaplan, a theoretical particle physicist at Johns Hopkins University and the producer of the award-winning documentary Particle Fever, pro...
Opening a window on quantum gravity
Yale University has received a grant from the W. M. Keck Foundation to fund experiments that researchers hope will provide new insights into quantum gravity. Jack Harris, associate professor of physic...
Confirming Einstein, scientists find 'spacetime foam' not slowing down photons from faraway gamma-ray burst
One hundred years after Albert Einstein formulated the general theory of relativity, an international team has proposed another experimental proof. In a paper published today in Nature Physics, resear...
Quantum foam
Quantum foam (also referred to as space-time foam) is a concept in quantum mechanics devised by John Wheeler in 1955. The foam is supposed to be conceptualized as the foundation of the fabric of the u...
Virtual black hole
In quantum gravity, a virtual black hole is a black hole that exists temporarily as a result of a quantum fluctuation of spacetime. It is an example of quantum foam and is the gravitational analog of...
Quantum gravity
Quantum gravity (QG) is a field of theoretical physics that seeks to describe the force of gravity according to the principles of quantum mechanics.The current understanding of gravity is based on Alb...
Quantum gravity - Wikipedia
Loop quantum cosmology
Loop quantum cosmology (LQC) is a finite, symmetry-reduced model of loop quantum gravity (LQG) that predicts a "quantum bridge" between contracting and expanding cosmological branches.The distinguishi...
Brane cosmology
Brane cosmology refers to several theories in particle physics and cosmology related to string theory, superstring theory and M-theory.
The central idea is that the visible, four-dimensional univ...
Vacuum energy
Vacuum energy is an underlying background energy that exists in space throughout the entire Universe. One contribution to the vacuum energy may be from virtual particles which are thought to be partic...
Zero-energy universe
The zero-energy universe theory states that the total amount of energy in the universe is exactly zero: its amount of positive energy in the form of matter is exactly canceled out by its negative ener...
Vacuum genesis
Vacuum genesis (zero-energy universe) is a scientific theory about the Big Bang that states that the universe began as a single particle arising from an absolute vacuum, similar to how virtual particl...
Eternal inflation
Eternal Inflation is an inflationary universe model, which is itself an outgrowth or extension of the Big Bang theory. In theories of eternal inflation, the inflationary phase of the Universe's expans...
Minisuperspace
In quantum gravity, the phase space is infinite dimensional as we are dealing with a field theory. An approximation which is sometimes taken is to only consider the largest wavelength modes of the ord...
A New ‘Einstein’ Equation Suggests Wormholes Hold Key To Quantum Gravity
A new Einsteinian equation, ER=EPR, may be the clue physicists need to merge quantum mechanics with general relativity.
Ashtekar variables
In the ADM formulation of General relativity one splits spacetime into spatial slices and time, the basic variables are taken to be the induced metric, , on the spatial slice (the metric induced on th...
Mixed anomaly
In theoretical physics, a mixed anomaly is an example of an anomaly: it is an effect of quantum mechanics — usually a one-loop diagram — that implies that the classically valid general covariance and ...
Confirming Einstein, scientists find 'spacetime foam' not slowing down photons from faraway gamma-ray burst
One hundred years after Albert Einstein formulated the general theory of relativity, an international team has proposed another experimental proof. In a paper published today in Nature Physics, resear...
Amplituhedron
An amplituhedron is a geometric structure that enables simplified calculation of particle interactions in some quantum field theories. In planar N = 4 supersymmetric Yang–Mills theory, an amplituhedro...
FRW/CFT duality
The FRW/CFT duality is a conjectured duality for Friedmann-Robertson-Walker models inspired by the AdS/CFT correspondence. It assumes that the cosmological constant is exactly zero, which is only the ...
Gravitational instanton
In mathematical physics and differential geometry, a gravitational instanton is a four-dimensional complete Riemannian manifold satisfying the vacuum Einstein equations. They are so named because they...
IR/UV mixing
In theoretical physics, it is usually possible to organize physical phenomena according to the energy scale or distance scale. The theory of renormalization group is based on this paradigm. The short-...
Immirzi parameter
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 mea...
Composite gravity
In theoretical physics, composite gravity refers to models that attempted to derive general relativity in a framework where the graviton is constructed as a composite bound state of more elementary pa...
Black hole electron
In physics, there is a speculative notion that if there were a black hole with the same mass and charge as an electron, it would share many of the properties of the electron including the magnetic mom...
Group field theory
Group field theory (GFT) is a quantum field theory in which the base manifold is taken to be a Lie group. It is closely related to background independent quantum gravity approaches such as loop quantu...
Euclidean quantum gravity

In physics, a Wick rotation, named after Gian-Carlo Wick, is a method of finding a solution to dynamics problems in n dimensions, by transposing their descriptions in n+1 dimensions, by trading o...
Spin foam
In physics, a spinfoam or spin foam is a topological structure made out of two-dimensional faces that represents one of the configurations that must be summed to obtain a Feynman's path integral (fun...