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Classical limits of quantum systems are shown to lead to different conceptions of spaces different from the classical one underlying the process of quantization of such systems. The accent is put in situations where traces of…

Quantum Physics · Physics 2022-07-22 Thierry Paul

Precise rules are developed in order to formalize the reasoning processes involved in standard non-relativistic quantum mechanics, with the help of analogies from classical physics. A classical or quantum description of a mechanical system…

Quantum Physics · Physics 2007-05-23 Robert B. Griffiths

We derive the gravitational Lagrangian to all orders of curvature when the canonical constraint algebra is deformed by a phase space function as predicted by some studies into loop quantum cosmology. The deformation function seems to be…

General Relativity and Quantum Cosmology · Physics 2020-11-25 Rhiannon Cuttell , Mairi Sakellariadou

We study the passive influence of quantum matter fluctuations on the expansion parameter of a congruence of timelike geodesics in a semiclassical regime. In particular, we show that, the perturbations of this parameter can be considered to…

Mathematical Physics · Physics 2016-08-08 Nicolò Drago , Nicola Pinamonti

Field theories that are generally covariant but nongravitational at tree level typically give rise to an emergent gravitational interaction whose strength depends on a physical regulator. We consider emergent gravity models in which scalar…

High Energy Physics - Theory · Physics 2022-03-11 Shikha Chaurasia , Joshua Erlich , Yiyu Zhou

Most approaches towards a quantum theory of gravitation indicate the existence of a minimal length scale of the order of the Planck length. Quantum mechanical models incorporating such an intrinsic length scale call for a deformation of…

General Relativity and Quantum Cosmology · Physics 2025-05-21 Won Sang Chung , Georg Junker , Hassan Hassanabadi

In the paper a review of results for recovering of the weak equivalence principle in a space with deformed commutation relations for operators of coordinates and momenta is presented. Different types of deformed algebras leading to a space…

Quantum Physics · Physics 2023-02-03 Kh. P. Gnatenko , V. M. Tkachuk

An heuristic semiclassical procedure that incorporates quantum gravity induced corrections in the description of photons and spin 1/2 fermions is reviewed. Such modifications are calculated in the framework of loop quantum gravity and they…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Luis Urrutia

The consistent embedding of Loop Quantum Gravity (LQG) effects within the Standard Model requires a rigorous understanding of how Planck-scale deformations manifest at low energies. While phenomenological approaches often introduce…

General Physics · Physics 2026-03-03 Leonardo P. G. De Assis

We review applications of noncommutative geometry in canonical quantum gravity. First, we show that the framework of loop quantum gravity includes natural noncommutative structures which have, hitherto, not been explored. Next, we present…

General Relativity and Quantum Cosmology · Physics 2012-03-29 Johannes Aastrup , Jesper M. Grimstrup

Quantum vacuum fluctuations tend to be strongly anti-correlated, which reduces their observable effects. However, time dependence can upset the cancellation of these anti-correlated fluctuations and greatly enhance their effects. This form…

General Relativity and Quantum Cosmology · Physics 2014-03-12 Victor Parkinson , L. H. Ford

Phenomenological models aiming to join gravity and quantum mechanics often predict effects that are potentially measurable in refined low-energy experiments. For instance, modified commutation relations between position and momentum, that…

When a confined system interacts with its walls (treated quantum mechanically), there is an intertwining of degrees of freedom. We show that this need not lead to entanglement, hence decoherence. It will generally lead to error. The wave…

Quantum Physics · Physics 2008-11-26 L. Schulman

Deformed relativistic kinematics, expected to emerge in a flat-spacetime limit of quantum gravity, predicts violation of discrete symmetries at energy scale in the vicinity of the Planck mass. Momentum-dependent deformations of the C, P and…

High Energy Physics - Phenomenology · Physics 2020-11-04 Wojciech Wislicki

Application of the so-called refined algebraic quantization scheme for constrained systems to the relativistic particle provides an inner product that defines a unique Fock representation for a scalar field in curved space-time. The…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Helmut Rumpf

Standard quantum mechanics and gravity are used to estimate the mass and size of idealized gravitating systems where position states of matter and geometry become indeterminate. It is proposed that well-known inconsistencies of standard…

General Relativity and Quantum Cosmology · Physics 2014-12-05 Craig J. Hogan

The longstanding issue of general covariance in effective models of quantum gravity is addressed, which arises when canonical quantum gravity leads to a semiclassical model described by an effective Hamiltonian constraint. In the context of…

General Relativity and Quantum Cosmology · Physics 2026-03-05 Cong Zhang , Jerzy Lewandowski , Yongge Ma , Jinsong Yang

It has recently been shown that small quantum subsystems generically equilibrate, in the sense that they spend most of the time close to a fixed equilibrium state. This relies on just two assumptions: that the state is spread over many…

Quantum Physics · Physics 2015-05-30 Anthony J. Short , Terence C. Farrelly

We reconsider the Rovelli-Smolin model of gravity coupled to the Klein-Gordon time field with an eye towards capturing the degrees of freedom of the scalar field lost in the framework in which time is deparametrized by the scalar field.…

General Relativity and Quantum Cosmology · Physics 2016-02-03 Jerzy Lewandowski , Hanno Sahlmann

An algebraic formulation of general relativity is proposed. The formulation is applicable to quantum gravity and noncommutative space. To investigate quantum gravity we develop the canonical formalism of operator geometry, after…

High Energy Physics - Theory · Physics 2007-05-23 Masaru Siino