Large Grants

Mini-Grants

Tufts University

Co-Investigators

Jaume Garriga,

*Universitat de Baecelona*

Vitaly Vanchurin,

*Tufts University*

Project Title

Probabilities in the Landscape

Project Summary

Models of cosmic inflation, combined with recent developments in string theory, point to a new cosmological paradigm, where distant parts of the universe have diverse properties and different particle physics. Inflationary scenarios, which explain the observed homogeneity of the universe, predict that on very large scales the universe is very inhomogeneous, with vast regions still in the state of exponential inflationary expansion, and "normal" regions like ours constantly being formed. The cosmological and particle physics parameters, such as the dark energy density or elementary particle masses, may have different values in different parts of such an eternally inflating universe. These variable parameters cannot be predicted with certainty, and one can only hope to determine their probability distributions. The proposed research will focus on the conceptual and technical problems that have been encountered in the calculation of probabilities in the eternally inflating universe. We shall also consider applications of the general theory to specific observables, such as the dark energy and dark matter densities, the magnitude of density fluctuations that seeded the structure formation in the universe, and the neutrino masses.

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