Genesis with general relativity asymptotics in beyond Horndeski theory

Dark Energy: Beyond General Relativity?

The late-time accelerated expansion of the universe is a major challenge for cosmology. It may well be that a solution to this problem will require a theory of gravitation beyond General Relativity. It is emphasized that precision cosmology will strongly constrain the possibilities by using observational data probing the background as well as the inhomogeneities.

Exploring gravitational theories beyond Horndeski

We have recently proposed a new class of gravitational scalar-tensor theories free from Ostrogradski instabilities, in Ref. [1]. As they generalize Horndeski theories, or “generalized” galileons, we call them G. These theories possess a simple formulation when the time hypersurfaces are chosen to coincide with the uniform scalar field hypersurfaces. We confirm that they contain only three propa...

On the general relativity theory

In Appendix III of the fifth edition of his book Space, Time, Matter [15] henceforth cited as W (which has not been translated into English), Hermann Weyl derived for the first time, motivated by cosmological considerations, the general frequency shift formula for sources and observers moving arbitrarily in a general spacetime. In his discussion of cosmology (W, 39) he argued for a non-stationa...

Einstein’s General Theory of Relativity

Weakly coupled gravity beyond general relativity

We explore four-dimensional (4D) weakly coupled gravity beyond general relativity in an on-shell language, focusing on the graviton three-point vertex. This admits a novel structure which can be attributed to a term cubic in the Riemann tensor. We consider a generalization of the Shapiro time delay experiment that involves polarized gravitons and show that the new vertex leads to causality viol...