Why the Cosmological Constant Is Small and Positive
Abstract
Within conventional big bang cosmology, it has proven to be very difficult to understand why today's cosmological constant is so small. In this paper, we show that a cyclic model of the universe can naturally incorporate a dynamical mechanism that automatically relaxes the value of the cosmological constant, including contributions to the vacuum density at all energy scales. Because the relaxation time grows exponentially as the vacuum density decreases, nearly every volume of space spends an overwhelming majority of the time at the stage when the cosmological constant is small and positive, as observed today.
 Publication:

Science
 Pub Date:
 May 2006
 DOI:
 10.1126/science.1126231
 arXiv:
 arXiv:astroph/0605173
 Bibcode:
 2006Sci...312.1180S
 Keywords:

 ASTRONOMY;
 Astrophysics
 EPrint:
 15 pages, 1 figure