5/23/00

Dawn Levy, News Service (650) 725-1944; e-mail: dawnlevy@stanford.edu

Physicists roast and toast Susskind

Last weekend physicists flocked to the Teaching Center in the Science and Engineering Quadrangle to attend "LennyFest," a two-day symposium in honor of string theorist Leonard Susskind on the occasion of his 60th birthday. Susskind is the Felix Bloch Professor of Physics, one of the newest members of the National Academy of Sciences and director of the Stanford Institute of Theoretical Physics.

More common in Europe, such symposia are an important way in which scientists honor their intellectual leaders. Characterized by lectures on technical topics that have been influenced by the honored party, they also contain a lighter element ­ the "roast," or good-natured tales about the scientist that may prove enlightening or embarrassing.

Along with Y. Nambu of the University of Chicago, Susskind first posited that the fundamental constituents of the universe are not geometric points having no size, but rather are tiny strings. At "LennyFest," string-theory­related topics from black holes and cosmology to supersymmetry and quantum field theory were presented by physicists Juan Maldacena, David Gross, Tom Banks, Ashoke Sen, Andy Strominger, Jeff Harvey, Joe Polchinski, Igor Klebanov, John Schwarz, Edward Witten, Savas Dimopoulos and 1999 Nobel Prize winner Gerard 't Hooft.

Susskind himself gave a lecture about objects that appear to travel faster than the speed of light. He talked about an experiment a physicist could do to test the theory of possible faster-than-light travel. Measuring wave displacement, the experiment would employ wave packets of light, visualized as strings rather than particles, bouncing off a brick wall. When one end of a string hits the wall, it is deflected backward before the string's center of gravity reaches the wall. The effect would be to make things appear to happen before the event that initiated it. While the theory helps explain some puzzling aspects of space and time, the discussion made it clear that physicists still have much ground to explore.

Not all of the symposium was deep thought, however. Professor Steve Chu, chair of the Department of Physics and 1997 Nobel Prize winner, roasted Susskind with his recollection of a recent incident, when Susskind entered his office "deeply troubled" after his election to the National Academy of Sciences. The document that disturbed Susskind, Chu said, stated "that from here on in you'd uphold the highest standards of scientific integrity and honesty."

Susskind's theories are "pretty heavy stuff," Chu said. "I tried to figure out how a person like Lenny could get to be a person like Lenny." So he dug around Susskind's curriculum vitae and found some revelatory facts. Susskind, known for his informality and creativity, actually completed his baccalaureate degree requirements after receiving his doctorate. "He was actually a professor, and he needed his B.S. degree to, well, B.S."

Chu also found out that Susskind has another degree ­ in plumbing. Susskind's father had been a plumber, and Chu delighted the audience by showing that plumbing laid the context for string theory. He took a well-known Susskind schematic and turned it 90 degrees. The audience responded with laughter because, reoriented, the diagram looked like a schematic of a toilet flushing. Chu noted features like "spiraling down, black holes and so forth." This parallel explained, Chu said, why Susskind was "never willing to let go of certain principles, such as if you have something coming in, coming out, keep track of all the phases, of all the amplitudes, everything. The key point about all this, as every plumber knows, is when you flush, there's a backup somewhere."

Kidding aside, Gross lauded Susskind for his "incredible intuition" and the fact that "being around Lenny is never boring. These are great gifts." Sen called Susskind "a constant source of inspiration." Banks, who said he learned about physics from Susskind while a postdoctoral scholar, cherished Susskind's advice in exploring tough questions: "Your head hurts afterward, but you feel good about yourself for making the effort."

Malcolm Beasley, a physicist and dean of the School of Humanities and Sciences, was impressed by a colloquium Susskind gave at Stanford after famed physicist and teacher Richard Feynman died in 1988. "It was sentimental without being maudlin. He talked about the man. He talked about the science. I was really touched by that and never forgot it."

The event was sponsored by the Stanford Linear Accelerator Center, the School of Humanities and Sciences, the Department of Physics and the Stanford Institute of Theoretical Physics.

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By Dawn Levy