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Time in relativity theory has a status different from that adopted by standard quantum mechanics, where time is considered as a parameter measured with reference to an external absolute Newtonian frame. This status strongly restricts its…

Quantum Physics · Physics 2023-10-26 M. Basil Altaie

We continue our analysis of a quantum cosmology model describing a flat Friedmann--Lema\^itre--Robertson--Walker universe filled with a (free) massless scalar field and an arbitrary perfect fluid. For positive energy density in the scalar…

General Relativity and Quantum Cosmology · Physics 2022-04-08 Steffen Gielen , Lucía Menéndez-Pidal

Time is absolute in standard quantum theory and dynamical in general relativity. The combination of both theories into a theory of quantum gravity leads therefore to a "problem of time". In my essay I shall investigate those consequences…

General Relativity and Quantum Cosmology · Physics 2009-09-22 Claus Kiefer

Research in quantum gravity strongly suggests that our world in not fundamentally spatiotemporal, but that spacetime may only emerge in some sense from a non-spatiotemporal structure, as this paper illustrates in the case of causal set…

History and Philosophy of Physics · Physics 2018-04-09 Christian Wuthrich

A classical dynamical system in a four-dimensional Euclidean space with universal time is considered. The space is hypothesized to be originally occupied by a uniform substance, pictured as a liquid, which at some time became supercooled.…

High Energy Physics - Theory · Physics 2013-06-19 Michael Grady

We analyze the canonical quantum dynamics of the isotropic Universe in a metric approach by adopting a self-interacting scalar field as relational time. When the potential term is absent we are able to associate the the expanding and…

General Relativity and Quantum Cosmology · Physics 2023-09-15 Eleonora Giovannetti , Fabio Maione , Giovanni Montani

The spacetime structure of the spatially uniformly expanding universe is described in terms of a kind of global space and global time instead of the space and time we usually recognize. The global space at some instant is a space in which…

Astrophysics · Physics 2022-08-31 Yoshio Kubo

In this note, we attempt to provide some insights into the structure of non-perturbative descriptions of quantum gravity using known examples of gauge-theory / gravity duality. We argue that in familiar examples, a quantum description of…

High Energy Physics - Theory · Physics 2010-03-24 Mark Van Raamsdonk

We present a relational framework in which temporal structure is not fundamental but emerges from correlations within a globally stationary quantum state. Each subsystem includes an internal clock, and conditional states evolve effectively…

Quantum Physics · Physics 2025-12-19 Amir Hossein Ghasemi

Familiar textbook quantum mechanics assumes a fixed background spacetime to define states on spacelike surfaces and their unitary evolution between them. Quantum theory has changed as our conceptions of space and time have evolved. But…

General Relativity and Quantum Cosmology · Physics 2008-06-09 James B. Hartle

Time has been an elusive concept to grasp. Although we do not yet understand it properly, there has been advances made in regards to how we can explain it. One such advance is the Page-Wootters mechanism. In this mechanism time is seen as…

Quantum Physics · Physics 2019-12-02 Leandro R. S. Mendes , Diogo O. Soares-Pinto

Although time is one of our most intuitive physical concepts, its understanding at the fundamental level is still an open question in physics. For instance, time in quantum mechanics and general relativity are two distinct and incompatible…

Quantum Physics · Physics 2021-01-27 Eduardo O. Dias

While Quantum Gravity remains elusive and Quantum Field Theory retains the interpretational difficulties of Quantum Mechanics, we have introduced an alternate approach to the unification of particles, fields, space and time, suggesting that…

General Physics · Physics 2012-11-21 Yousef Ghazi-Tabatabai

The ontology proposed in this paper is aimed at demonstrating that it is possible to understand the counter-intuitive predictions of quantum mechanics while still retaining much of the framework underlying classical physics, the implication…

Quantum Physics · Physics 2019-08-20 Roderick Sutherland

The need for a time-shift invariant formulation of quantum theory arises from fundamental symmetry principles as well as heuristic cosmological considerations. Such a description then leaves open the question of how to reconcile global…

Quantum Physics · Physics 2019-06-26 Leon Loveridge , Takayuki Miyadera

An extrinsic time is identified in most isotropic and homogeneous cosmological models by matching them with the ideal clock - a parametrized system whose only "degree of freedom" is time -. Once this matching is established, the…

General Relativity and Quantum Cosmology · Physics 2009-10-22 S. C. Beluardi , Rafael Ferraro

We investigate quantum cosmological models in an n-dimensional anisotropic universe in the presence of a massless scalar field. Our basic inspiration comes from Chodos and Detweiler's classical model which predicts an interesting behaviour…

General Relativity and Quantum Cosmology · Physics 2018-02-14 F. A. P. Alves-Júnior , M. L. Pucheu , A. B. Barreto , C. Romero

Quantum gravity has become a fertile interface between gravitational physics and quantum many-body physics, with its double goal of identifying the microscopic constituents of the universe and their fundamental dynamics, and of…

General Relativity and Quantum Cosmology · Physics 2017-10-10 Daniele Oriti

A complete model of the universe needs at least three parts: (1) a complete set of physical variables and dynamical laws for them, (2) the correct solution of the dynamical laws, and (3) the connection with conscious experience. In quantum…

High Energy Physics - Theory · Physics 2007-05-23 Don N. Page

Non-relativistic quantum mechanics is shown to emerge from classical mechanics through the requirement of a relativity principle based on special transformations acting on position and momentum uncertainties. These transformations keep the…

Quantum Physics · Physics 2007-05-23 Léon Brenig