Why is the Universe Just Right for Life?

Abstract

A longstanding mystery concerning the laws of physics and the cosmological initial conditions is that they are peculiarly well suited to the emergence of life – at least, life as we know it. The favoured explanation is that the region of space we call “the universe” is in fact merely an infinitesimal fragment of a vast and elaborate assemblage of universes, collectively termed “the multiverse.” According to the multiverse theory, each universe has its own distinctive laws and initial conditions, perhaps chosen randomly. Only in those universes which, by chance, the circumstances are just right for life will observers like us emerge and puzzle over the weird bio-friendliness of their own particular universe. Although popular, the multiverse theory falls far short of a complete explanation of physical reality, because it assumes a set of meta-laws, including a universe-generating mechanism, which must simply be accepted as a brute fact. I this paper I review the multiverse theory and discuss its shortcomings, and outline the challenge of trying to construct a theory of physical existence that does not depend on arbitrary starting assumptions.