SPACE-TIME VARIATION OF COUPLING CONSTANTS AND FUNDAMENTAL MASSES

Abstract

We review recent works discussing the effects of variation of fundamental "constants" on a variety of physical systems. These are motivated by theories unifying gravity with other interactions that suggest the possibility of temporal and spatial variation of the fundamental constants in an expanding Universe. The effects of any potential variation of the fine-structure constant and fundamental masses could be seen in phenomena covering the lifespan of the Universe, from Big Bang nucleosynthesis to quasar absorption spectra to modern atomic clocks. We review recent attempts to find such variations and discuss some of the most promising new systems where huge enhancements of the effects may occur.