An aternative to Einstein's GRT

Einstein constructed his general relativity theory about a century ago. Adhering to two basic principles, namely, (1)general relativity principle and (2)Equivalence principle, he arrived at his celebrated action, which had also been proposed by Hilbert and led to Einstein's equation. However, there are some seemingly inherent singularity that has been plaguing physicists. Such singularity concerns the beginning of time and space. Now, a very interesting paper [1] has just appeared in PRL, addressing such issues by a different GRT, as first suggested by Eddington. This new action is also invariant under general coordinate transformations. And, in this paper, it was shown that, due to some extra terms particularly relevant in large density regions, this new theory may get around those long standing issues.

Eddington’s Theory of Gravity and Its Progeny
Ma´ximo Ban˜ados, P. Universidad Cato´lica de Chile, Avenida Vicuna Mackenna 4860, Santiago, Chile Astrophysics, University of Oxford, DWB, Keble Road, Oxford, OX1 3RH, United Kingdom Pedro G. Ferreira, Astrophysics, University of Oxford, DWB, Keble Road, Oxford, OX1 3RH, United Kingdom
(Received 21 March 2010; published 2 July 2010)
We resurrect Eddington’s proposal for the gravitational action in the presence of a cosmological constant and extend it to include matter fields. We show that the Newton-Poisson equation is modified in the presence of sources and that charged black holes show great similarities with those arising in Born-Infeld electrodynamics coupled to gravity. When we consider homogeneous and isotropic space-times, we
find that there is a minimum length (and maximum density) at early times, clearly pointing to analternative theory of the big bang.We thus argue that the modern formulation of Eddington’s theory, Born-Infeld gravity, presents us with a novel, nonsingular description of the Universe.
DOI: 10.1103/PhysRevLett.105.011101 PACS numbers: 04.50. h, 98.80. k

[1]PRL 105, 011101 (2010)