Spacetime Foam and the Cosmological Constant

Abstract

In the saddle point approximation, the Euclidean path integral for quantum gravity closely resembles a thermodynamic partition function, with the cosmological constant $\Lambda$ playing the role of temperature and the ``density of topologies'' acting as an effective density of states. For $\Lambda <0$, the density of topologies grows superexponentially, and the sum over topologies diverges. In thermodynamics, such a divergence can signal the existence of a maximum temperature. The same may be true in quantum gravity: the effective cosmological constant may be driven to zero by a rapid rise in the density of topologies.

8 pages, LaTeX. Two minor revisions (scaling parameter corrected with new reference; qualification added on Borel summability)

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