Was inflation necessary for the existence of time?

Sandra Stupar, Vlatko Vedral

Published 2017-10-11Version 1

Modern physics has unlocked a number of mysteries regarding the early Universe, such as the baryogenesis, the unification of the strong and electroweak forces and the nucleosynthesis. However, understanding the very early Universe, close to the Planck epoch, still presents a major challenge. The theory of inflation, which is assumed to have taken place towards the end of the very early Universe, has been introduced in order to solve a number of cosmological problems. However, concrete observational evidence for inflation is still outstanding and the physical mechanisms behind inflation remain mostly unknown. In this paper we argue for inflation from a different standpoint. In order for time to have any concrete physical meaning in the very early and the early Universe, the capacity of the Universe to measure time - its size or, equivalently, memory - must be at least as large as the number of clock "ticks" that need to be recorded somewhere within the Universe. Using this simple criterion, we provide a sketch proof showing that in the absence of inflation the subsystems of the Universe might not have been able to undertake the synchronised evolution described by the time we use today.