Inflationary cosmology and creation of matter in the universe (Q2762010)

The first working model of inflationary type, the Starobinsky model developed in 1979, was based on an examination of conformal anomaly in quantum gravity. The next modelling step was what is now called the ``old'' inflation theory. This modification of the big-bang theory was based on the theory of supercooling during cosmological phase transitions. The model was so attractive that now most textbooks concerned with astrophysical cosmology describe the inflation process as an exponential expansion of the universe in a supercooled false vacuum state. During the preceding twenty years the ``new'' inflationary theory according to which inflation does not occur in the false vacuum state has gradually become the standard paradigm of astrophysical cosmology. In addition to resolving a variety of problems of the big-bang theory such as the homogeneity problem, isotropy problem, entropy problem, flatness problem, horizon problem, the problem of formation of the large-scale structure of the universe, and the primordial monopole problem, the development of chaotic inflation theory has made predictions which seem to be in good agreement with observational data bases. Presently, no other modification of the big-bang theory is available that can make all of these cosmological predictions. NEWLINENEWLINENEWLINEA brief review of the history and current status of inflationary theory is given. In addition, the article describes recent progress made in the theory of creation of matter in the universe in the process of reheating after inflation. The inflation process may begin even if there was no thermal equilibrium in the early universe and it may start even at the Planckian density in which case the problem of initial condition for inflation can be easily resolved.