became hot again. This idea attracted much attention because it could provide a unique solution to many difficult problems of the standard Big Bang theory. In particular, it could explain why the universe is so large and so uniform. However, as Guth immediately realized, this scenario did not quite work as intended: the decay of the false vacuum would make the universe extremely inhomogeneous. New inflation In 1981, during a seminar by Stephen Hawking on quantum gravity , Linde developed another version of inflationary theory which he called "New inflation". He demonstrated that the bubbles not joining up (see page 138 of A Brief History of Time, Chapter 8) could be solved if there was a bubble that contained our region of the universe in it. He also said that the phase transition must have taken place slowly inside the bubble. This theory resolved the problems of the original model proposed by Guth while preserving most of its attractive features. A few months later, a similar scenario was proposed by Andreas Albrecht and Paul Steinhardt which referenced Linde's paper. Soon after that, it was realized that the new inflationary scenario also suffered from some problems. Most of them arose because of the standard assumption that the early universe initially was very hot, and inflation occurred during the cosmological phase transitions. Chaotic inflation In 1983, Linde abandoned some of the key principles of old and new inflation and proposed a more general inflationary theory, chaotic inflation. Chaotic inflation occurs in a much broader class of theories, without any need for the assumption of initial thermal equilibrium. The basic principles of this scenario became incorporated in most of the presently existing realistic versions of inflationary theory. Chaotic inflation changed the way we think about the beginning of inflation. Later on, Linde also proposed a possible modification of the way in which inflation may end, by developing the hybrid inflation scenario. In that model, inflation ends due to the "waterfall" instability . Creation of matter in the universe According to the inflationary theory, all elementary particles in the universe emerged after the end of inflation, in a process called reheating. The first version of the theory of reheating, which is essentially the theory of creation of matter in the universe, was developed in 1982 by Alexander Dolgov and Linde, and also by L.F. Abbott, Edward Farhi and Mark B. Wise. In 1994, this