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Theories of the very early Universe that use scalar fields (i.e., the so-called inflationary models of the Universe) have now come into wide use. The inflationary universe approach may perhaps solve some of the most difficult enigmas about the Universe as a whole. The inflationary universe forms a good bridge between the quantum theory of the birth of the Universe (which is still in the initial stages of development) and the standard hot Big Bang theory (which is well established, at least qualitatively). Therefore, an understanding of the basic ideas of inflation is a must for astronomers interested in the broad picture of the science. (1)

There are already several descriptions of the inflationary universe, from a Scientific American paper by Guth and Steinhardt (1984) to a paper by Linde in Uspekhi Fizicheskikh Nauk (Linde, 1984), available in the literature. However, the first of these was written without any formulae at all, while the second is rather difficult, even for the average theoretical physicist.

Intermediate-level papers exist in other branches of physics; a brilliant example of such a paper is Lipkin's "Quark Theory for Pedestrians," which was written in the early sixties. This paper was the source of my inspiration. In obvious contrast with the driver of a car, a pedestrian is a person in good health, but without high-powered equipment. In Lipkin's context, such a person can understand simple formulae and even prefers them to vague descriptions. However, the "pedestrian" does not necessarily understand the details of complicated calculations.

I wish to write the astronomical equivalent of Lipkin's "pedestrian" paper. An observational astronomer is the analogue of a "pedestrian" in modern particle physics; the average observer is perhaps not greatly aware of the current trends in elementary particle physics and field theory. On the other hand, astronomers are mathematically oriented enough (via celestial mechanics, electromagnetic theory, magneto-hydrodynamics, nuclear reactions, etc.) that there is no negative attitude towards formulae in general. What the astronomer lacks is a knowledge of recent developments in particle physics and field theory. The astronomer should not be blamed for this, because these branches of physics are developing in a very peculiar fashion: some subfields of it are progressing comparatively slowly, with experimental verifications at each and every step, while other subfields progress rapidly.

1 There is another independent approach to the inflationary theory, one based on polarization of the vacuum by the space-time curvature (Starobinskii 1980) - see footnote on page 36. Back.

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