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In an attempt to re-establish space-time as an essential frame for formulating quantum gravity - rather than an "emergent" one -, we find that exact invariance under scale transformations is an essential new ingredient for such a theory.…

General Relativity and Quantum Cosmology · Physics 2009-09-21 Gerard 't Hooft

In general relativity, the description of spacetime relies on idealised rods and clocks, which identify a reference frame. In any concrete scenario, reference frames are associated to physical systems, which are ultimately quantum in…

Quantum Physics · Physics 2021-07-28 Flaminia Giacomini

When one takes into account gravitation, the measurement of space and time cannot be carried out with infinite accuracy. When quantum mechanics is reformulated taking into account this lack of accuracy, the resolution of the measurement…

General Relativity and Quantum Cosmology · Physics 2009-03-16 Rodolfo Gambini , Jorge Pullin

Curvature is a key notion in General Relativity, characterizing the local physical properties of spacetime. By contrast, the concept of curvature has received scant attention in nonperturbative quantum gravity. One may even wonder whether…

General Relativity and Quantum Cosmology · Physics 2023-06-27 R. Loll

Quantum inequalities are bounds on negative time-averages of the energy density of a quantum field. They can be used to rule out exotic spacetimes in general relativity. We study quantum inequalities for a scalar field with a background…

General Relativity and Quantum Cosmology · Physics 2014-07-16 Eleni-Alexandra Kontou , Ken D. Olum

We present a theory of gravity based on Einstein's general relativity that is motivated by the paradoxes associated with time in relativistic rotating frames and certain exact solutions of Einstein's equations. We show that we can resolve…

General Relativity and Quantum Cosmology · Physics 2011-06-14 Robert D. Bock

We explore the weak-field phenomenology of a compact star spacetime modified by quantum gravitational corrections derived from the effective field theoretical (EFT) approach by Calmet et al. [1]. These corrections, encoded in non-local…

General Relativity and Quantum Cosmology · Physics 2026-02-10 Reggie C. Pantig , Ali Ovgun , Gaetano Lambiase

From a theory of an abstract quantum information the theory of general relativity can be deduced by means of few and physically good founded reasons. "Abstract" quantum information means that primarily no special meaning is connected with…

General Physics · Physics 2010-08-27 Thomas Görnitz

In general relativity (GR), spacetime geometry is no longer just a background arena but a physical and dynamical entity with its own degrees of freedom. We present an overview of approaches to quantum gravity in which this central feature…

General Relativity and Quantum Cosmology · Physics 2014-08-20 Abhay Ashtekar , Martin Reuter , Carlo Rovelli

When applied to some models of noncommutative geometry, the formalism of relative locality predicts the occurrence of a delay in the time of arrival of massless particle of different energies emitted by a distant observer. In this letter,…

High Energy Physics - Theory · Physics 2017-04-26 S. Mignemi , A. samsarov

It is argued that some approaches to non-perturbative quantum general relativity lack a sensible continuum limit that reproduces general relativity. The basic problem is that generic physical states lack long ranged correlations, because…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Lee Smolin

Gravitons should have momentum just as photons do; and since graviton momentum would cause compression rather than elongation of spacetime outside of matter; it does not appear that gravitons are compatible with Swartzchild's spacetime…

General Physics · Physics 2019-10-24 Michael Byrne

We study the limitations for defining spatial and temporal intervals when the only available reference frame is a single composite quantum system, whose internal degrees of freedom serve as a temporal reference, a clock, and whose center of…

Quantum Physics · Physics 2026-01-27 Davide Mattei , Esteban Castro-Ruiz

In an attempt to generalize general relativity, we propose a new Hermitian theory of gravity. Space-time is generalized to space-time-momentum-energy and both the principles of general covariance and equivalence are extended. The theory is…

General Relativity and Quantum Cosmology · Physics 2008-05-30 Christiaan Mantz , Tomislav Prokopec

It is shown that the attempt to extend the notion of ideal measurement to quantum field theory leads to a conflict with locality, because (for most observables) the state vector reduction associated with an ideal measurement acts to…

General Relativity and Quantum Cosmology · Physics 2008-02-03 Rafael D. Sorkin

The standard formulation of quantum theory relies on a fixed space-time metric determining the localisation and causal order of events. In general relativity, the metric is influenced by matter, and is expected to become indefinite when…

Quantum Physics · Physics 2020-06-08 Esteban Castro-Ruiz , Flaminia Giacomini , Alessio Belenchia , Časlav Brukner

New general results of non-existence and rigidity of spacelike submanifolds immersed in a spacetime, whose mean curvature is a time-oriented causal vector field, are given. These results hold for a wide class of spacetimes which includes…

Differential Geometry · Mathematics 2019-11-12 uan A. Aledo , Rafael M. Rubio , Juan J. Salamanca

A satisfactory theory of quantum gravity will very likely require modification of our classical perception of space-time, perhaps by giving it a 'foamy' structure at scales of order the Planck length. This is expected to modify the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Subir Sarkar

A satisfactory theory of quantum gravity may necessitate a drastic modification of our perception of space-time, by giving it a foamy structure at distances comparable to the Planck length. It is argued in this essay that the experimental…

General Relativity and Quantum Cosmology · Physics 2009-09-11 John. Ellis , N. E. Mavromatos , D. V. Nanopoulos

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