**Rodger I. Thompson**

Steward Observatory, University of Arizona

**Abstract**

It is now widely accepted that we live in a universe with an accelerating expansion. We can embrace the cosmological constant as the cause but then must confront the realization that all current calculations of the value of the constant are on the order of 50 magnitudes greater than its measured value. The most popular alternatives to the geometric view are cosmologies with rolling scalar fields as the source of the acceleration. Under the new physics assumption that the electromagnetic field is also coupled to the scalar field, the values of the fundamental constants such as the proton to electron mass ratio, mu, and the fine structure constant, alpha, are also predicted to roll with time. This talk looks at the impact of the measured values of the fundamental constant mu in the early universe on four different rolling scalar field cosmologies and the coupling constant of mu with the field. The observed limits on the variance of mu force either a limit on the variance of the equation of state parameter w to only a few percent from -1 or a value for the coupling constant much lower than its expected value. These findings are putting stringent constraints on the combination of new physics and alternative cosmologies and suggest that compliance with the values of the fundamental constants is an essential test for any proposed cosmology or new physics.

** 2012 May 23, 13:30**

**IA/U.Porto**

Centro de Astrofísica da Universidade do Porto (Auditorium)

Rua das Estrelas, 4150-762 Porto