For some time, theoretical physicists have been exploring the idea that the basic building blocks of nature are strings, tiny vibrating loops. Although there are many theoretical arguments in support of this idea, the very small size of the strings has made experimental tests difficult. Under certain conditions, strings produced shortly after the big bang will grow along with the expanding universe, so that today they would be of cosmic size. Such cosmic strings can be detected in various ways. In particular they emit intense gravitational waves, and could be the brightest objects visible in the new era of gravitational wave astronomy. For more information, click here.

Joe Polchinski has been a Permanent Member of the KITP and a professor in the Department of Physics since 1992. He received his B.S. from Caltech in 1975 and his Ph.D. from UC Berkeley in 1980. He then held postdoctoral positions at the Stanford Linear Accelerator Center and Harvard, and was a member of the faculty of the University of Texas at Austin from 1984 to 1992. His awards include a Fannie and John Hertz graduate fellowship (1975-80), a National Science Foundation postdoctoral fellowship (1980-82), and an A.P. Sloan Foundation research fellowship (1985-89). He was elected a Fellow of the American Physical Society in 1997. In 1998 he completed a two volume graduate textbook on string theory, which has become the standard text and reference in the field.