the number of all possible universes, to be about 10^10^16 if we do not consider the fact that humans as observers are limited in their ability to distinguish more universes. If this is taken into account, there could be as many as 10^10^10^7 universes. By analyzing the slow-roll inflation mechanism that initially generated the quantum fluctuations, the scientists could estimate the number of resulting universes at 10^10^10^7. Inflation and string theory A significant advance in this area was obtained when the theory of inflationary multiverse was implemented in the context of string theory. In 2000, Raphael Bousso and Joseph Polchinski proposed using the regime of eternal inflation and transitions between many different vacua in string theory for solving the cosmological constant problem. At that time, no stable or metastable vacua of string theory were actually known. A possible mechanism of string theory vacuum stabilization was proposed in 2003 by Shamit Kachru, Renata Kallosh, Linde, and Sandip Trivedi, who also found that all of these vacua describing expanding universe are metastable, i.e. they must eventually decay (see KKLT mechanism). Then Michael R. Douglas and his collaborators estimated that the total number of different stringy vacua can be as large as 10500, or even more, and Leonard Susskind developed the string theory landscape scenario based on investigation of cosmological phase transitions between different string theory vacua. One of the main challenges of this theory is to find the probability of living in each of these different parts of the universe. However, once string theory is invoked, it is extremely difficult to return to the previous picture of a single universe. In order to do so, one would need to prove that only one of the many vacua of string theory is actually possible, and to propose an alternative solution of the many problems which can be solved by using the anthropic cosmological principle in the context of the theory of inflationary multiverse., Linde continues his work on the theory of inflationary multiverse. In particular, Renata Kallosh and Andrei Linde, together with their collaborators, developed a theory of cosmological attractors. This is a broad class of versions of inflationary cosmology which provide one of the best fits to the latest observational data. Honors and awards In July 2012, Linde was an inaugural awardee of the Fundamental Physics Prize, the creation of physicist and internet entrepreneur Yuri Milner. In 2014, he was a co-recipient,