arXiv:hep-th/0602091hep-th
Populating the Landscape: A Top Down Approach
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Abstract
We put forward a framework for cosmology that combines the string landscape with no boundary initial conditions. In this framework, amplitudes for alternative histories for the universe are calculated with final boundary conditions only. This leads to a top down approach to cosmology, in which the histories of the universe depend on the precise question asked. We study the observational consequences of no boundary initial conditions on the landscape, and outline a scheme to test the theory. This is illustrated in a simple model landscape that admits several alternative inflationary histories for the universe. Only a few of the possible vacua in the landscape will be populated. We also discuss in what respect the top down approach differs from other approaches to cosmology in the string landscape, like eternal inflation.
Another alternative was proposed by Hawking & Hertog (Phys Rev D, 2006, see below): walk the present values surface back to a superposition of possible universes and study the mechanisms that generate probabilities near one. That then is their way of asking about the degree of…
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