DOES THE FINE STRUCTURE CONSTANT VARY WITH TIME AND DISTANCE?

Victor Flambaum, University of New South Wales

Abstract
Were the laws of nature the same ten billion light years away from us? A change in the fine structure constant could be detected via shifts in the rest wavelengths of resonance transitions in quasar absorption systems. We have developed a new approach which improves the sensitivity of this method by an order of magnitude (the effect that we study is 10 times larger than that studied in the previous works, see Phys. Rev. Lett. 82, 888, 1999). We have measured the fine structure constant in 49 absorption systems covering look-back times from 0.2 to 0.9 times the age of the Universe.

Theories unifying gravity with other interactions suggest the possibility of spatial and temporal variation of the fundamental "constants" in the Universe. Current interest is high because in superstring theories, which have additional spatial dimensions compactified on tiny scales, any variation of the mean size of the extra dimensions results in changes of the 3-dimensional observed coupling constants. Also, we can now probe variations at the level predicted in inflationary models, where the amplitude and spectrum of spatial variations in alpha are linked to gravitational wave fluctuations and density fluctuations measured by COBE. Our initial results hinted that alpha may have been smaller in the past (Phys. Rev. Lett., 82, 884, 1999). Startlingly, new results based on independent data support the same effect.

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