Scientists' views on time travel and interstellar space flight.
J. Richard Gott
*Professor of astrophysics, Princeton University, Princeton, New Jersey
*Author, Time Travel in Einstein's Universe: The Physical Possibilities of Travel Through Time (Houghton Mifflin, 2001)
William R. Alschuler
*Professor of science, California Institute of the Arts, San Francisco, California
*Author, The Science of UFOs: What If They're Real? (St. Martin's Press, 2001)