Inflation Circa 1983

Abstract

The hot big bang cosmology provides a reliable accounting of the evolution of the Universe from ti 0.01 s after ‘the bang’ until the present (10–20 Byr after ‘the bang’). This is a truly impressive achievement. There are, however, a handful of very fundamental ‘cosmological facts’ which the model by itself fails to elucidate. They include: the large-scale homogeneity, the isotropy, the small-scale inhomogeneity, the near critical expansion rate, the predominance of matter, the ‘monopole problem’, and the extremely tiny value of the present cosmological term. The inflationary Universe scenario proposed by Guth and recently modified by Linde, and Albrecht and Steinhardt (new inflation) offers the possibility of explaining all but the last of these puzzling facts as the result of an early epoch of exponential expansion driven by a large vacuum energy. Inflation makes the present state of the observable Universe virtually insensitive to the initial state of the Universe. Unfortunately, at present there is no model of new inflation which both resolves the cosmological puzzles and leads to sensible particle physics. A general prescription for the cosmologically-desirable Higgs potential does exist.