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Within the closed universe, we obtain the amplitude and frequency of gravitational waves in the terms of discrete wave numbers, wave propagation time, and cosmological constant using the deviation equation in the first-order perturbed…

General Relativity and Quantum Cosmology · Physics 2021-05-27 Jafar Khodagholizadeh , Amir H. Abbassi , Ali Vahedi , Komeil Babaei

Stochastic quantisation is applied to the problem of calculating real-time evolution on a Minkowskian space-time lattice. We employ optimized updating using reweighting, or gauge fixing, respectively. These procedures do not affect the…

High Energy Physics - Lattice · Physics 2009-11-13 Denes Sexty

The Hamiltonian constraint system is the canonical formulation of a physical system with a Hamiltonian constrained to vanish. In terms of the canonical variables, we define what we call reference observable, with respect to which other…

General Relativity and Quantum Cosmology · Physics 2012-10-30 Junichi Iwasaki

Quantum mechanics rests on the assumption that time is a classical variable. As such, classical time is assumed to be measurable with infinite accuracy. However, all real clocks are subject to quantum fluctuations, which leads to the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 J. M. Isidro , J. L. Gonzalez-Santander , P. Fernandez de Cordoba

A cosmological model is formulated in the context of a scalar-tensor theory of gravity in which the entire cosmic background evolution is due to a complex scalar field evolving in Minkowski spacetime, such that its (dimensional) modulus is…

General Physics · Physics 2019-09-24 Meir Shimon

We argue that the time measured by a light clock operating with photons rather than classical light requires a refinement of the standard clock postulate in general relativity. In the presence of a gravitational field, already the one-loop…

General Relativity and Quantum Cosmology · Physics 2009-02-12 Raffaele Punzi , Frederic P. Schuller , Mattias N. R. Wohlfarth

In this work, we investigate cosmologies where the gravitational constant varies in time, with the aim of explaining the accelerated expansion without a cosmological constant. We achieve this by considering a phenomenological extension to…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-18 Ekim Taylan Hanımeli , Brahim Lamine , Alain Blanchard , Isaac Tutusaus

We analyze the possible variability of the effective Newtonian gravitational constant $G_{\rm N}$ in space and time in the framework of the geometric scalar theory of gravity suggested by M. Novello et al. [JCAP 06, 014 (2013); arXiv:…

General Relativity and Quantum Cosmology · Physics 2020-10-20 K. A. Bronnikov

Noncommutative geometry is a mathematical framework that expresses the structure of space-time in terms of operator algebras. By using the tools of quantum mechanics to describe the geometry, noncommutative space-times are expected to give…

Mathematical Physics · Physics 2024-07-03 Kilian Hersent

Lorentz time is replaced by three parameters: a global time, a local rate of aging, and a new spatial coordinate. This enables successful reconstruction of relativity's observables in a four dimensional Euclidean hyperspace. The new…

Astrophysics · Physics 2007-05-23 Gary D. Warren

A fundamental description of time can be consistent not only with the usual monotonic behavior but also with a periodic physical clock variable, coupled to the degrees of freedom of a system evolving in time. Generically, one would in fact…

Quantum Physics · Physics 2022-05-25 Martin Bojowald , Luiz Martinez , Garrett Wendel

In this paper we address the problem of the arrow of time from a cosmological point of view, rejecting the traditional entropic approach that defines the future direction of time as the direction of the entropy increase: from our…

Quantum Physics · Physics 2009-11-07 Mario Castagnino , Luis Lara , Olimpia Lombardi

The definition of a reference frame in General Relativity is achieved through the construction of a congruence of time-like world-lines. In this framework, splitting techniques enable us to express physical phenomena in analogy with Special…

General Physics · Physics 2026-05-13 Matteo Luca Ruggiero

In this paper the results obtained by Minic and his colleagues on the uncertainty relation of the pair "cosmological constant - volume of space-time", where cosmological constant is a dynamical quantity, are reconsidered and generalized…

High Energy Physics - Theory · Physics 2009-12-15 Alexander E. Shalyt-Margolin

We investigate the conditions under which cosmological variations in physical `constants' and scalar fields are detectable on the surface of local gravitationally-bound systems, such as planets, in non-spherically symmetric background…

General Relativity and Quantum Cosmology · Physics 2011-07-19 Douglas J. Shaw , John D. Barrow

Using the relativistic concept of time dilation we show that a superposition of gravitational potentials can lead to nonunitary time evolution. For sufficiently weak gravitational potentials one can still define, for all intents and…

The background field equations for homogeneous and isotropic spacetime are derived in conformal scalar-tensor gravity. The background temporal evolution is entirely driven by the dynamical evolution of the scalar field, i.e. particle…

General Physics · Physics 2018-10-12 Meir Shimon

In order to obtain a well defined quantum gravity we define the spacetime in relation to the "phenomenology" of the physical interactions; however we shall to speculate with this "in General". Besides, we comment the reasons that give to…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Marcelo Botta Cantcheff

General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big bounce. A classical theory of…

General Physics · Physics 2011-02-08 Walter Petry

We consider a dynamical systems formulation for models with an exponential scalar field and matter with a linear equation of state in a spatially flat and isotropic spacetime. In contrast to earlier work, which only considered linear…

General Relativity and Quantum Cosmology · Physics 2022-07-13 Artur Alho , Woei Chet Lim , Claes Uggla
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