Annu. Rev. Astron. Astrophys. 1991. 29: 325-362 Copyright © 1991 by Annual Reviews. All rights reserved

7. OUTLOOK

The inflationary model epitomizes the deep influence very high energy particle physics can have on cosmology. The idea is an attractive one, and, given the current momentum on the frontier of particle physics and cosmology, further epicycles are not ruled out. In the last analysis, however, astronomers should judge it by its impact on present day observations. Does it leave relics that are observed today? The formation of structures, the values of the density parameter, and the cosmological constant are examples of such relics. The present evidence on these issues is at best ambivalent and at worst embarrassing for the current theories of inflation. This may be because the particle physicists have not yet been clever enough to hit the jackpot of the correct unification theory.