Dear all, for the topic https://www.physicsforums.com/threads/problems-with-the-theory-of-inflation.905230/ I came across the following paper: https://arxiv.org/abs/1505.01456. In this paper the following arguments are given why the horizon problem is a fake problem. It raised by me the following question: Why is it assumed in the formulation of the horizon problem that the observed thermal equilibrium from the CMB has to be explained by thermalization right after t=0? Or: Why did the energy content in the universe have to start out of equilibrium, while equilibrium itself is statistically much more common/probable than an out-of-equilibrium state? Maybe 'there is something about the combination of statistical mechanics and gravity I don't grasp. Can anyone elaborate? Many thanks!