Seminarium Teorii Względności i Grawitacji

Time is absolute in standard quantum theory and dynamical in general relativity. The combination of the two theories into a theory of quantum gravity thus leads to a `problem of time'. In my talk, I shall investigate those consequences for the concept of time that can be drawn without a detailed knowledge of quantum gravity.The only assumptions are the experimentally supported universality of the superposition principle and the recovery of general relativity in the classical limit. Attention is focused on quantum cosmology - the application of quantum theory to the Universe as a whole. Among the consequences are the fundamental timelessness of quantum cosmology, the approximate nature of a semiclassical time, and the correlation of entropy with the size of the Universe.The last consequence gives rise to the irreversibility of our world.Ref.: C. Kiefer and P. Peter, Universe 2022, 8, 36 [arXiv:2112.05788] and references therein. The talk will be broadcasted in the room 1.40