|Theoretical cosmologist Andrei Linde is the author of theories of the origin of the universe that have revolutionized cosmology. He helped lay the foundation for the concept of inflationthe idea that the universe began not with a hot big bang but with an extraordinarily rapid expansion of space in a vacuum-like statewhile working at the Lebedev Physical Institute in his native Russia. A graduate of Moscow State University, Dr. Linde took his Ph.D. in physics at Lebedev in 1975 and became a professor there in 1985. He was the Morris Loeb Lecturer at Harvard in 1987, joined the staff of CERN in 1989, and came to Stanford in 1990. After his initial contribution to inflationary cosmology, Dr. Linde went on to propose other promising versions of this theory, such as "chaotic inflation." Published in 1986, his theory of a chaotic self-reproducing inflationary universe suggests that our universe is one of many inflationary universes that sprout from an eternal cosmic tree. His current research also involves phase transitions in the early universe, large-scale structure formation, and cosmological constraints on the properties of elementary particles. In three papers published last year with his wife, Renata Kallosh, Dr. Linde proposed that the dark energy, the haunting theoretical phenomenon reminiscent of Einstein's "cosmological constant," which is presently stretching spacetime at an ever increasing rate, may eventually become negative. As a result, the universe may begin collapsing in 10 to 100 billion years and end in a "big crunch." Our universe, in their model, is middle-aged, not, as once thought, at the beginning of its life cycle. But according to Dr. Linde's inflationary theory, while our "bubble" may die, the multiverse of bubbles will go on forever. The winner of the Lomonosov Award of the Academy of Sciences of the USSR, Dr. Linde received the Oskar Klein Medal in physics in 2001 and last year shared the Dirac Medal awarded by the Abdus Salam International Centre for Theoretical Physics in Trieste, Italy on the centenary of Nobel laureate Paul Dirac's birth. He is the author of two books on inflationary theory and 194 scientific papers.