The Arrow Of Time In The Landscape

Abstract

We argue that an understanding of the Arrow of Time is urgently required if recent string-theoretic ideas about cosmology are to be made to function. In the string Landscape, the nucleation of baby universes is postulated to "populate" the multiverse. Here we argue that baby universes can only have an Arrow if they \emph{inherit} one; the problem of explaining the Arrow is thus reduced to explaining it in the case of the original universe. Motivated by the Ooguri-Vafa-Verlinde formulation of "creation from nothing" in the context of string theory, we propose that the original universe was created along a spacelike surface with the topology of a torus. Using deep results in global differential geometry, we are able to show that the geometry of this surface had to be non-generic. This geometric "specialness" is communicated to matter through the inflaton. Thus we have a theory of the Arrow which is intrinsically geometric, which incorporates Inflation, and which allows universes in the Landscape to begin with physically acceptable initial conditions.