# Populating the landscape: A Top down approach

@article{Hawking2006PopulatingTL, title={Populating the landscape: A Top down approach}, author={Stephen William Hawking and Thomas Hertog}, journal={Physical Review D}, year={2006}, volume={73}, pages={123527} }

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…

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#### References

SHOWING 1-10 OF 90 REFERENCES

Why does inflation start at the top of the hill

- Physics
- 2002

We show why the universe started in an unstable de Sitter state. The quantum origin of our universe implies one must take a ``top down'' approach to the problem of initial conditions in cosmology, in…

Observational consequences of a landscape

- Physics
- 2005

In this paper we consider the implications of the ``landscape paradigm [1], [2] for the large scale properties of the universe. The most direct implication of a rich landscape is that our local…

Probabilities in the inflationary multiverse

- Physics
- 2006

Inflationary cosmology leads to the picture of a 'multiverse', involving an infinite number of (spatially infinite) post-inflationary thermalized regions, called pocket universes. In the context of…

Birth of inflationary universes

- Physics
- 1983

A cosmological model is proposed in which the Universe is created by quantum tunneling from ''nothing'' into a de Sitter space. The tunneling is described by a de Sitter-- p Hawking--Moss instanton.…

M-theory observables for cosmological space-times

- Physics
- 2001

We discuss the construction of the analog of an S-matrix for space-times that begin with a Big-Bang and asymptote to an FRW universe with nonnegative cosmological constant. When the cosmological…

Can the universe afford inflation

- Physics
- 2004

Cosmic inflation is envisioned as the 'most likely' start for the observed universe. To give substance to this claim, a framework is needed in which inflation can compete with other scenarios and the…

Is there a string theory landscape

- Physics
- 2004

We examine recent claims of a large set of flux compactification solutions of string theory. We conclude that the arguments for AdS solutions are plausible. The analysis of meta-stable dS solutions…

Cosmology and the S matrix

- Physics
- 2005

We study conditions for the existence of asymptotic observables in cosmology. With the exception of de Sitter space, the thermal properties of accelerating universes permit arbitrarily long…

Multiple universes, cosmic coincidences, and other dark matters

- Physics
- 2004

Even when completely and consistently formulated, a fundamental theory of physics and cosmological boundary conditions may not give unambiguous and unique predictions for the universe we observe;…

Brane new world

- Physics
- 2000

We study a Randall-Sundrum cosmological scenario consisting of a domain wall in anti\char21{}de Sitter space with a strongly coupled large N conformal field theory living on the wall. The AdS-CFT…