Stephen Hawking - Imaginary Time

June 11, 1989 - Stephen Hawking, theoretical physicist and author of "A Brief History of Time”, speaking in Northrop Auditorium at the University of Minnesota, as part of the Abigail and John Van Vleck lecture series. As Lucasian Professor of Mathematics at England's Cambridge University, Hawking occupies a chair once held by Isaac Newton. Hawking is renowned for his theories of black holes and the structure of space-time. He found that black holes - dense objects with gravity so strong even light can't escape - emit radiation just outside the boundary beyond which nothing can overcome the pull of gravity. He also initiated the concept that the continuity of space-time breaks down at infinitesimally small distances. Hawking has suffered from Lou Gehrig's disease, or amyotrophic lateral sclerosis, and now speaks about 10 words a minute with the aid of a computer voice synthesizer. By preparing speeches in advance, however, he can "speak" at a normal rate, although with an American accent.