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The apparent Lorentz invariance of the laws of physics does not imply that space-time is indeed minkowskian. We consider a scenario where Lorentz invariance is only an approximate property of equations of matter above a certain distance…

Astrophysics · Physics 2008-02-03 Luis Gonzalez-Mestres

The influence od space-time curvature on quantum matter which can be theoretically described by covariant wave equations has not been experimentally established yet. In this paper we analyse in detail the suitability of the Ramsey atom beam…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Jürgen Audretsch , Karl-Peter Marzlin

Gravitational lensing constitutes one of the most direct observational manifestations of spacetime curvature and provides a powerful probe of compact astrophysical objects. In this work, we present a comprehensive analysis of the bending of…

General Relativity and Quantum Cosmology · Physics 2026-04-21 Partha Pratim Basumallick , Saheb Das , Bhaswati Mandal , Subhadip Sau

New measurements of the cosmic microwave background (CMB) by the Planck mission have greatly increased our knowledge about the Universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our…

Cosmology and Nongalactic Astrophysics · Physics 2013-07-03 Maria Archidiacono , Elena Giusarma , Steen Hannestad , Olga Mena

Using in situ data, accumulated in the turbulent magnetosheath by the Magnetospheric Multiscale (MMS) Mission, we report a statistical study of magnetic field curvature and discuss its role in the turbulent space plasmas. Consistent with…

Quantum gravity is studied in a semiclassical approximation and it is found that to first order in the Planck length the effect of quantum gravity is to make the low energy effective spacetime metric energy dependent. The diffeomorphism…

High Energy Physics - Theory · Physics 2009-11-11 Lee Smolin

In this letter we study the propagation of light in the neighbourhood of magnetised neutron stars. Thanks to the optical properties of quantum vacuum in the presence of a magnetic field, light emitted by background astronomical objects is…

Quantum Physics · Physics 2016-08-16 Arnaud Dupays , Cécile Robilliard , Carlo Rizzo , Giovanni F. Bignami

Quantum gravity is sometimes considered as a kind of metaphysical speculation. In this review, we show that, although still extremely difficult to reach, observational signatures can in fact be expected. The early universe is an invaluable…

General Relativity and Quantum Cosmology · Physics 2015-06-17 A. Barrau , T. Cailleteau , J. Grain , J. Mielczarek

For a certain example of a "doubly special relativity theory" the modified space-time Lorentz transformations are obtained from momentum space transformations by using canonical methods. In the sequel an energy-momentum dependent space-time…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Franz Hinterleitner

A local observer can measure only the values of fields at the point of his own position. By exploring the coordinate transformation between two Fermi frames, it is shown that two observers, having the same instantaneous position and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 H. Nikolic

In the present work, we theoretically investigate light deflection in the weak and strong field regimes for two regular spacetimes with corrections from loop quantum gravity. We treat analytically the expansions for both limits and use them…

General Relativity and Quantum Cosmology · Physics 2025-06-19 A. R. Soares , C. F. S. Pereira , R. L. L. Vitória , Marcos V. de S. Silva , H. Belich

Quantum gravitational effects usually are assumed to be important on small scale (Planck scale), but actually these effects are also very significant on large (cosmological) scales. It is recognized that in curved spacetime, the existence…

General Relativity and Quantum Cosmology · Physics 2022-04-18 Maryam Roushan , Narges Rashidi , Kourosh Nozari

Being able to perform explicit computations in a nonperturbative, Planckian regime is key to understanding quantum gravity as a fundamental theory of gravity and spacetime. Rather than a variety of different approaches to quantum gravity,…

High Energy Physics - Theory · Physics 2025-01-31 R. Loll

This paper explores the theoretical implications of quantum gravity by analyzing compact stellar objects, presenting three distinct models that serve as alternatives to traditional black holes. These models are characterized by their…

General Relativity and Quantum Cosmology · Physics 2025-12-02 Salvatore Samuele Sirletti , Piero Nicolini , Mariafelicia De Laurentis

In a previous paper, we derived the quantum states of a Dirac particle in a circular, intense magnetic field in the limit of low momentum perpendicular to the field with the purpose of giving a quantum description of the trajectory of an…

High Energy Astrophysical Phenomena · Physics 2017-06-28 Guillaume Voisin , Silvano Bonazzola , Fabrice Mottez

Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities. Objects falling into an overdensity appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts.…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-03 David J. Bacon , Sambatra Andrianomena , Chris Clarkson , Krzysztof Bolejko , Roy Maartens

The study of physics at the Planck scale has garnered significant attention due to its implications for understanding the fundamental nature of the universe. At the Planck scale, quantum fluctuations challenge the classical notion of…

General Relativity and Quantum Cosmology · Physics 2024-11-26 Weihu Ma , Yu-Gang Ma

Gravitational lenses can provide crucial information on the geometry of the Universe, on the cosmological scenario of formation of its structures as well as on the history of its components with look-back time. In this review, I focus on…

Astrophysics · Physics 2009-10-31 Y. Mellier

Over the last decade there were significant advances in the understanding of quantum gravity coupled to point particles in 3D (2+1-dimensional) spacetime. Most notably it is emerging that the theory can be effectively described as a theory…

High Energy Physics - Theory · Physics 2015-06-11 Giovanni Amelino-Camelia , Michele Arzano , Stefano Bianco , Riccardo J. Buonocore

When the gravitational lensing potential can be approximated by that of circularly symmetric system affected by weak perturbations, it is found that the shape of the resulting (tangential) caustics is entirely specified by the local…

Astrophysics · Physics 2007-05-23 Jin H. An