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Contrary to our immediate and vivid sensation of past, present, and future as continually shifting non-relational modalities, time remains as tenseless and relational as space in all of the established theories of fundamental physics. Here…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Joy Christian

Being able to measure time, whether directly or indirectly, is a significant advantage for an organism. It permits it to predict regular events, and prepare for them on time. Thus, clocks are ubiquitous in biology. In the present paper, we…

Other Quantitative Biology · Quantitative Biology 2017-06-23 Andrei D. Robu , Christoph Salge , Chrystopher L. Nehaniv , Daniel Polani

It is expected that a quantum theory of gravity will radically alter our current notion of spacetime geometry. However, contrary to what was commonly assumed for many decades, quantum gravity effects could manifest in scales much larger…

General Relativity and Quantum Cosmology · Physics 2026-05-14 Eduardo A. B. Oliveira , Andre G. S. Landulfo

Systems invariant under the reparametrization of time were treated as constrained systems within Hamilton-Jacobi formalism. After imposing the integrability conditions the time-dependent Schr\"odinger equation was obtained. Three examples…

High Energy Physics - Theory · Physics 2009-11-10 Dumitru Baleanu

It is postulated there is not a precise static instant in time underlying a dynamical physical process at which the relative position of a body in relative motion or a specific physical magnitude would theoretically be precisely determined.…

General Physics · Physics 2007-05-23 Peter Lynds

Compared with time independent Hamiltonians, the dynamics of generic quantum Hamiltonians $H(t)$ are complicated by the presence of time ordering in the evolution operator. In the context of digital quantum simulation, this difficulty…

Quantum Physics · Physics 2024-04-08 Jacob Watkins , Nathan Wiebe , Alessandro Roggero , Dean Lee

Physical devices operating out of equilibrium are inherently affected by thermal fluctuations, limiting their operational precision. This issue is pronounced at microscopic and especially quantum scales and can only be mitigated by…

Attempts to quantize general relativity encounter an odd problem. The Hamiltonian that normally generates time evolution vanishes in the case of general relativity as a result of diffeomorphism invariance. The theory seems to be saying that…

General Relativity and Quantum Cosmology · Physics 2009-04-23 Olaf Dreyer

A clock synchronization thought experiment is modeled by a diffeomorphism invariant "time delay" observable. In a sense, this observable probes the causal structure of the ambient Lorentzian spacetime. Thus, upon quantization, it is…

General Relativity and Quantum Cosmology · Physics 2014-02-04 Béatrice Bonga , Igor Khavkine

Classical clocks measure proper time along their worldline, and Riemannian geometry provides tools for predicting the time shown by clocks in both flat and curved spacetimes. Common approaches to time in quantum systems, based for instance…

General Relativity and Quantum Cosmology · Physics 2025-01-14 Joseph Balsells , Martin Bojowald

We present a pseudoclassical mechanics model which exhibits gauge symmetry and time-reparametrization invariance. As such, first- and second-class constraints restrict the phase space, and the Hamiltonian weakly vanishes. We show that the…

High Energy Physics - Theory · Physics 2023-04-07 Mauricio Valenzuela

It is often claimed that the fundamental laws of physics are deterministic and time-symmetric and that therefore our experience of the passage of time is an illusion. This paper will critically discuss these claims and show that they are…

Quantum Physics · Physics 2023-04-20 Barbara Drossel

Space-like and time-like invariant space-time intervals are used to analyse measurements of spatial and temporal distances. The former are found to be Lorentz invariant --there is no `relativistic length contraction', whereas the latter…

General Physics · Physics 2009-09-01 J. H. Field

In this paper, we further develop a recently proposed theory of time based on wavefunction collapse in general relativity. It is based on the postulations that quantum states, which violate the momentum and Hamiltonian constraints,…

General Relativity and Quantum Cosmology · Physics 2026-04-23 Sung-Sik Lee

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

It is shown that Quantum Mechanics is ambiguous when predicting relative frequencies for an entangled system if the measurements of both subsystems are performed in spatially separated events. This ambiguity gives way to unphysical…

Quantum Physics · Physics 2016-01-27 Carlos Lopez

We reply to the comments by P.Midodashvili about our previous paper [1]. We argue that, contrary to the conclusions in Refs. [2,3], the Generalized Uncertainty Principle proposed by Ng and van Dam in Ref. [4] is compatible with the…

High Energy Physics - Theory · Physics 2007-05-23 Fabio Scardigli , Roberto Casadio

In it's usual presentation, classical mechanics appears to give time a very special role. But it is well known that mechanics can be formulated so as to treat the time variable on the same footing as the other variables in the extended…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Michael Reisenberger , Carlo Rovelli

Quantum timeless approaches solve the problem of time by recovering the usual unitary evolution of quantum theory relative to a clock in a stationary quantum Universe. For some Hamiltonians of the Universe, such as those including an…

Quantum Physics · Physics 2026-04-14 Simone Rijavec

The equations of Hamiltonian gravity are often considered ugly cousins of the elegant and manifestly covariant versions found in the Lagrangian theory. However, both formulations are fundamental in their own rights because they make…

General Relativity and Quantum Cosmology · Physics 2017-12-27 Martin Bojowald