Related papers: GR 20 Parallel Session A3: Modified Gravity
Modified theories of gravity usually present new degrees of freedom, as well as higher order derivatives, wrong signs in certain terms and complicated couplings already present in the Lagrangian from the beginning or originated by the field…
Lecture notes from the mini-course "Topics in Lorentz Geometry" taught at the University of S\~{a}o Paulo, in March/2019. The text has three parts: (i) an overall view of linear algebra in the pseudo-Euclidean space $\mathbb{R}^n_\nu$, with…
The discovery of cosmic acceleration has raised the intriguing possibility that we are witnessing the first breakdown of General Relativity on cosmological scales. In this article I will briefly review current attempts to construct a…
DGRAV News: We hear that.... DGRAV Student Travel Grants Town Hall Meeting GRG Society Research Briefs: What's new in LIGO Conference Reports: Christodoulou Conference Obituaries: Stephen Hawking (1942-2018) Joseph Polchinski (1954-2018)
GGR News: -we hear that..., by David Garfinkle -Network of gravitational-wave detectors, by Stan Whitcomb Research Briefs: -New tests of general relativity, by Quentin Bailey Conference Reports: -Theory meets data analysis, by Steve…
GGR News: GGR Program at the APS meeting in Anaheim, CA by David Garfinkle We hear that..., by David Garfinkle 100 years ago, by David Garfinkle Research Briefs: Endpoint of the Gregory-Laflamme Instability, by Gary Horowitz Conference…
In this report I will give a summary of some of the main topics covered in Session A3, mathematical studies of the field equations, at GRG18, Sydney. Unfortunately, due to length constraints, some of the topics covered at the session will…
In this thesis, we use numerical relativity to investigate gravitational waves from binary black holes in extensions of GR. We first study spherically symmetric gravitational collapse in cubic Horndeski theories of gravity. By varying the…
We present qualitative arguments in favor of an extension of the theory of the gravitational interaction beyond that resulting from the Hilbert-Einstein action. To this end we consider a locally conformal invariant theory of gravity,…
In this report we discuss three aspects: 1) Semiclassical gravity theory (SCG): 4 levels of theories describing the interaction of quantum matter with classical gravity; 2) Alternative Quantum Theories: Discerning those which are derivable…
These notes partly touch the topic of the talk given by the author at the XXXVIII Workshop on Geometric Methods in Physics, hold in June-July 2019 in Bia\l{}owie\.{z}a, Poland. They consist of a short and self-contained introduction to the…
We give a pedagogical introduction into the field of (modified) teleparallel theories of gravity. Our presentation is fairly self-contained. In particular, we carefully explain the basic principles of metric-affine approaches to gravity.…
News: - APS Prize on gravitation, by Cliff Will - TGG elections, by David Garfinkle - We hear that... by Jorge Pullin Research Briefs: - Experimental Unruh radiation?, by Matt Visser - Why is the universe accelerating?, by Beverly Berger -…
The analysis of phase transitions in cosmological spacetimes shows that their existence requires a time-dependent apparent horizon radius, which in turn implies an equation of state different from that of a dark energy fluid. This condition…
This is the second of three papers on Conformal General Relativity (CGR). The conformal group is introduced here as the invariance group of the partial order of causal events in $n$D spacetime. Its general structure, discrete symmetries and…
We formulate the nonminimal aether-modified gravity whose action represents itself as a sum of the usual Einstein-Hilbert action and the CPT-even Lorentz-breaking aether-like gravity term proposed by Carroll. For this theory, we show that…
GGR News: we hear that... 100 years ago GGR program at the APS meeting in Savannah, GA Conference reports: GR20/Amaldi10 Conference in Warsaw, Poland School and workshop on quantum gravity in Brazil
Session B.3, on physics of the early Universe, of GR15 is briefly summarized.
The present work reveals a direct correspondence between modified theories of gravity (cosmology) and entropic cosmology based on the thermodynamics of apparent horizon. It turns out that due to the total differentiable property of entropy,…
This thesis is devoted to the study of gravitational theories which can be seen as modifications or generalisations of General Relativity. The motivation for considering such theories, stemming from Cosmology, High Energy Physics and…