MG14 - Talk detail

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Now that we can look back to the very early universe the question of whether the laws of physics are invariant with time takes on new relevance. The time base of laboratory and facility measurements is frustratingly short for looking for time variance but the look back time of astronomical measurements can be on the order of the age of the universe. This talk explores the role of astronomical observations of fundamental constants as monitors of physical law as a function of time. The fine structure constant alpha and most particularly the proton to electron mass ratio mu are featured here but other constants can be equally good monitors. Both mu and alpha are sensitive to the dark energy equation of state w and therefore serve as cosmological probes of possibly dynamical dark energy. In addition mu monitors the values of a combination of the QCD scale, the Higgs vacuum expectation value and the Yukawa couplings while alpha is directly sensitive to the Yukawa couplings. Measurements of the stability or variance of the fundamental constants therefore tests both the stability of fundamental physical parameters and the dark energy equation of state. In fact w need not vary to produce changes in the fundamental constants, it just has to be different from minus one. After setting forth the relationship of alpha and mu to both w and the physical parameters the impact of current constraints on the variance of mu and alpha are explored. Current limits on the variance of mu is at the one part in 10 million at roughly half the age of the universe. The talk concludes with the prospects for more stringent observational constraints.

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