چکیده

I’ll review a new, simpler explanation for the large scale geometry of spacetime, presented in our recent preprint arXiv:2201.07279. The basic ingredients are elementary and well-known, namely Einstein’s theory of gravity and Hawking’s method of computing gravitational entropy. The new twist is provided by the boundary conditions we proposed for big bang-type singularities, allowing conformal zeros but imposing CPT symmetry and analyticity at the bang. These boundary conditions allow gravitational instantons for universes with positive Lambda, massless radiation and positive or negative space curvature. We are thus able to infer the gravitational entropy for a complete set of semi-realistic, four-dimensional cosmologies. We find that the gravitational entropy can be significantly larger than the de Sitter entropy. To the extent that it is, the most probable large-scale geometry for the universe is flat, homogeneous and isotropic. I will briefly summarise what remains to be done to develop this picture into a principled and fully predictive theory of the cosmos.

کليدواژه ها

Entropy

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Neil Turok , 1400 , Gravitational entropy and the large scale geometry of spacetime , اولین کنفرانس بین المللی هولوگرافی و کاربردهای آن