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Further Evidence for Cosmological Evolution of the Fine Structure Constant

Phys. Rev. Lett. 87, 091301 – Published 9 August 2001
J. K. Webb, M. T. Murphy, V. V. Flambaum, V. A. Dzuba, J. D. Barrow, C. W. Churchill, J. X. Prochaska, and A. M. Wolfe


We describe the results of a search for time variability of the fine structure constant α using absorption systems in the spectra of distant quasars. Three large optical data sets and two 21 cm and mm absorption systems provide four independent samples, spanning 23% to 87% of the age of the universe. Each sample yields a smaller α in the past and the optical sample shows a 4σ deviation: Δα/α=-0.72±0.18×10-5 over the redshift range 0.5<z<3.5. We find no systematic effects which can explain our results. The only potentially significant systematic effects push Δα/α towards positive values; i.e., our results would become more significant were we to correct for them.

DOI: http://dx.doi.org/10.1103/PhysRevLett.87.091301

  • Received 29 December 2000
  • Published 9 August 2001

© 2001 The American Physical Society

Physics Focus

A Constant that Isn’t Constant

Published 9 August 2001

Authors & Affiliations

J. K. Webb1, M. T. Murphy1, V. V. Flambaum1, V. A. Dzuba1, J. D. Barrow2, C. W. Churchill3, J. X. Prochaska4, and A. M. Wolfe5

  • 1School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
  • 2DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge University, Cambridge CB3 0WA, United Kingdom
  • 3Department of Astronomy & Astrophysics, Pennsylvania State University, University Park, Pennsylvania 16802
  • 4Carnegie Observatories, 813 Santa Barbara Street, Pasadena, California 91101
  • 5Department of Physics and Center for Astrophysics and Space Sciences, University of California, San Diego, C-0424, La Jolla, California 920923

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