InflationandtheNewEraofHigh-PrecisionCosmology-MIT.pdfVIP

Alan H. Guth Inflation and the New Era of High-Precision Cosmology uring the past ?ve years our view of the universe has been D jolted by several new and surprising observations. On March 3, 1998, a New York Times headline announced quite accu- rately that “Shocked Cosmologists Find Universe Expanding Faster.” Instead of slowing due to gravitational attraction, the expansion of the universe was found to be speeding up! By Decem- ber of that year, Science magazine proclaimed the accelerating universe the “breakthrough of the year,” and the next month the cover of Scienti?c American heralded a “Revolution in Cosmology.” Shortly afterward new measurements of the cosmic background radiation overturned the prevailing beliefs about the geometry and total mass density of the universe. According to the New York Times of November 26, 1999, “Like the great navigators who ?rst sailed around the world, establishing its size and the curvature of 28 ) guth mit physics annual 2002 its surface, astronomers have made new observations that show with startling directness the large-scale geometry of the universe and the total amount of matter and energy that it contains. … All the data are consistent with a ?at universe, said scientists on the proj- ects and others who have read the teams’ reports.”The combined results of these observations have led to a new picture of our universe, in which the dominant ingredient is a mysterious substance dubbed “dark energy.” The second most abundant material is “dark matter,”and the ordinary matter that we are made of has been relegated to third place. Although substantially differ- ent from wh