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Quantum gravity (or quantum spacetime) is to unify general relativity and quantum mechanics into a single theoretical framework and presented as the most important open puzzle in fundamental physics. The development of a microscopic theory…

General Physics · Physics 2025-10-24 Su-Peng Kou

Quantum decoherence can arise due to classical fluctuations in the parameters which define the dynamics of the system. In this case decoherence, and complementary noise, is manifest when data from repeated measurement trials are combined.…

General Relativity and Quantum Cosmology · Physics 2011-09-13 G. J. Milburn

The dynamics of the expanding universe is analyzed in terms of the quantum geometrodynamical model. It is shown that the equations of quantum theory in the form of the eigenvalues equation similar to the stationary Schr\"{o}dinger equation…

General Relativity and Quantum Cosmology · Physics 2013-11-22 V. E. Kuzmichev , V. V. Kuzmichev

We show how quantum mechanics can be understood as a space-time theory provided that its spatial continuum is modelled by a variable real number (qrumber) continuum. Such a continuum can be constructed using only standard Hilbert space…

Quantum Physics · Physics 2007-05-23 J. Corbett , T. Durt

We present and analyze a gauge-invariant quantum theory of the Friedmann-Robertson-Walker universe with dust. We construct the reduced phase space spanned by gauge-invariant quantities by using the so-called relational formalism at the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Fumitoshi Amemiya , Tatsuhiko Koike

We present a theory based upon the treatment of the gravitational field as a sea of gravity quanta, as defined elsewhere. The resultant model for the Universe is a static one, like Einstein first saw, with a new feature: a local shrinking…

General Physics · Physics 2015-06-26 Antonio Alfonso-Faus

The theories of quantum mechanics and relativity dramatically altered our understanding of the universe ushering in the era of modern physics. Quantum theory deals with objects probabilistically at small scales, whereas relativity deals…

General Physics · Physics 2021-04-13 John Skilling , Kevin H. Knuth

An alternative formulation of the no-boundary initial state of the universe in the Euclidean quantum theory of gravity is proposed. Unlike the no-boundary Hartle-Hawking wave function, in which time appears together with macroscopic…

General Relativity and Quantum Cosmology · Physics 2023-10-24 Natalia Gorobey , Alexander Lukyanenko , A. V. Goltsev

We prove a theorem showing that quantum mechanics is not directly a stochastic process characterizing Brownian motion but rather its square root. This implies that a complex-valued stochastic process is involved. Schr\"odinger equation is…

Mathematical Physics · Physics 2012-01-31 Marco Frasca

We apply the complex de Broglie-Bohm formulation of quantum mechanics [1] to a spatially closed homogeneous and isotropic early Universe whose matter content are radiation and dust perfect fluids. We then show that an expanding classical…

General Relativity and Quantum Cosmology · Physics 2016-10-12 M. Fathi , S. Jalalzadeh , P. V. Moniz

We construct a well-defined lattice-regularized quantum theory formulated in terms of fundamental fermion and gauge fields, the same type of degrees of freedom as in the Standard Model. The theory is explicitly invariant under local Lorentz…

High Energy Physics - Theory · Physics 2013-05-30 Alexey A. Vladimirov , Dmitri Diakonov

Quantum operators of coordinates and momentum components of a particle in Minkowski space-time belong to a noncommutative algebra and give rise to a quantum phase space. Under some constraints, in particular, the Lorentz invariance…

High Energy Physics - Theory · Physics 2009-10-20 V. V. Khruschov

We show that the uncertainty in distance and time measurements found by the heuristic combination of quantum mechanics and general relativity is reproduced in a purely classical and flat multi-fractal spacetime whose geometry changes with…

High Energy Physics - Theory · Physics 2017-09-22 Gianluca Calcagni , Michele Ronco

A model for 2D-quantum gravity from the Virasoro symmetry is studied. The notion of space-time naturally arises as a homogeneous space associated with the kinematical (non-dynamical) SL(2,R) symmetry in the kernel of the Lie-algebra central…

General Relativity and Quantum Cosmology · Physics 2009-10-31 V. Aldaya , J. L. Jaramillo

A proposal is made for the quantum state of the universe that has an initial state that is macroscopically time symmetric about a homogeneous, isotropic bounce of extremal volume and that at that bounce is microscopically in the ground…

High Energy Physics - Theory · Physics 2015-05-13 Don N. Page

A fascinating and deep question about nature is what one would see if one could probe space and time at smaller and smaller distances. Already the 19th-century founders of modern geometry contemplated the possibility that a piece of empty…

High Energy Physics - Theory · Physics 2009-11-11 R. Loll , J. Ambjorn , J. Jurkiewicz

Gyroscopic systems in classical and quantum field theory are characterized by the presence of at least two scalar degrees of freedom and by terms that mix fields and their time derivatives in the quadratic Lagrangian. In Minkowski…

High Energy Physics - Theory · Physics 2022-11-15 Denis Comelli , Maicol Di Giambattista , Luigi Pilo

On the base of years of experience of working on the problem of the physical foundation of quantum mechanics the author offers principles of solving it. Under certain pressure of mathematical formalism there has raised a hypothesis of…

Quantum Physics · Physics 2007-05-23 V. E. Shemi-zadeh

No theory of four-dimensional quantum gravity exists as yet. In this situation the two-dimensional theory, which can be analyzed by conventional field-theoretical methods, can serve as a toy model for studying some aspects of quantum…

High Energy Physics - Theory · Physics 2015-06-26 J. Ambjorn , J. L. Nielsen , J. Rolf , R. Loll

A static non-singular 10-dimensional closed Friedmann universe of Planck size, filled with a perfect fluid with an equation of state with w = -2/3, can arise spontaneously by a quantum fluctuation from nothing in 11-dimensional spacetime. A…

General Relativity and Quantum Cosmology · Physics 2009-11-11 T. R. Mongan
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