Anthropic Bound on the Cosmological Constant

Phys. Rev. Lett. 59, 2607 – Published 30 November 1987
Steven Weinberg


In recent cosmological models, there is an "anthropic" upper bound on the cosmological constant Λ. It is argued here that in universes that do not recollapse, the only such bound on Λ is that it should not be so large as to prevent the formation of gravitationally bound states. It turns out that the bound is quite large. A cosmological constant that is within 1 or 2 orders of magnitude of its upper bound would help with the missing-mass and age problems, but may be ruled out by galaxy number counts. If so, we may conclude that anthropic considerations do not explain the smallness of the cosmological constant.


  • Received 5 August 1987
  • Published in the issue dated 30 November 1987

© 1987 The American Physical Society

Authors & Affiliations

Steven Weinberg

  • Theory Group, Department of Physics, University of Texas, Austin, Texas 78712

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