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

2.2.6. THE -TERM The cosmological constant was introduced by Einstein somewhat empirically to arrive at a static model of the universe (38). Although with the discovery of the cosmological redshift law by Hubble, the original need for disappeared, it is still taken seriously by many cosmologists. Observationally, the value of has to be of the order of the square of Hubble's constant at present. Thus | | 10^-35 s^-2.

The GUTs epoch generates a cosmological term purely from quantum field theoretical effects. The order of magnitude of this term is very large, however, about ~ 10⁷⁰ s^-2. Thus we have to find why the present -term is smaller by an order ~ 10^-105 of the primordial -term.