Weyl curvature hypothesis

The Weylkrümmungshypothese (named after Hermann Weyl ), which occurs in cosmology in the context of the application of Albert Einstein's general theory of relativity was proposed by the British mathematician and theoretical physicist Sir Roger Penrose, in an article in 1979, which returns for two fundamental problems in tried to give the physics. On one hand, one would like to understand why our universe appears remarkably spatially homogeneous and isotropic on the largest available observation scales ( and thus can be described mathematically by a simple Friedmann - Lemaître model), on the other hand is to ensure that the fundamental question of the origin of the second law of thermodynamics are addressed.

Penrose's view, an answer to these questions depends deeply related to the concept of a Entropieinhaltes of gravitational fields. Near the cosmological initial singularity ( the Big Bang ), he suggests, is the Entropieinhalt of the cosmological gravitational field have been extremely low ( compared with values ​​that would have been theoretically possible), and then began to increase monotonously. This process expressed for example in the formation of structures by the clumping of matter, the formation of galaxies and clusters of galaxies. Penrose connects the initially very low Entropieinhalt of the universe with an effective disappearance of Weylkrümmungstensors of the cosmological gravitational field near the big bang. Then, as he suspected, the dynamic influence of Weylkrümmung steadily increased, so this is responsible for a global increase in the amount of entropy in the universe. In consequence, a cosmological arrow of time is induced.

The Weylkrümmung represents gravitational effects such as tidal fields and gravitational radiation. Mathematically were discussed Penrose's ideas for Weylkrümmungshypothese as part of so-called isotropic cosmological initial singularity. Penrose sees the Weylkrümmungshypothese as a physically more convincing alternative to cosmic inflation ( a hypothetical phase of accelerated expansion of the universe young ) to explain the today observed nearly complete spatial homogeneity and isotropy of the universe.