Time’s Arrow in a Finite Universe

• 作者: Martin Tamm
• 来源期刊: 天文学与天体物理学国际期刊(英文)
• 学科: 数学
• 关键词: MULTIVERSE Time’s ARROW COSMOLOGY ENTROPY
• 年，卷（期）: 2015,（2）
• 页码范围: 70-78
• 页数: 9页
• 分类号: O1

摘要

In this paper, a simple model for a closed multiverse as a finite probability space is analyzed. For each moment of time on a discrete time-scale, only a finite number of states are possible and hence each possible universe can be viewed as a path in a huge but finite graph. By considering very general statistical assumptions, essentially originating from Boltzmann, we make the set of all such paths (the multiverse) into a probability space, and argue that under certain assumptions, the probability for a monotonic behavior of the entropy is enormously much larger then for a behavior with low entropy at both ends. The methods used are just very simple combinatorial ones, but the conclusion suggests that we may live in a multiverse which from a global point of view is completely time-symmetric in the sense that universes with Time’s Arrow directed forwards and backwards are equally probable. However, for an observer confined to just one universe, time will still be asymmetric.