he is keen to emphasize that time travel itself is a commonplace physical phenomenon, by this he means time travel into the future at varying rates through special relativity, he is not completely committed on the subject of time travel to the past. The book does say that nothing known excludes such travel, but he doesn't completely rule out the possibility that future research may prove it impossible. Copernicus method and Doomsday theory Gott first thought of his "Copernicus method" of lifetime estimation in 1969 when stopping at the Berlin Wall and wondering how long it would stand. Gott postulated that the Copernican principle is applicable in cases where nothing is known; unless there was something special about his visit (which he didn't think there was) this gave a 75% chance that he was seeing the wall after the first quarter of its life. Based on its age in 1969 (8 years), Gott left the wall with 50% confidence that it wouldn't be there in 1993 (1969 + 8·(1.5/0.5)). In fact, the wall was brought down in 1989, and 1993 was the year in which Gott applied his "Copernicus method" to the lifetime of the human race. His paper in Nature was the first to apply the Copernican principle to the survival of humanity; His original prediction gave 95% confidence that the human race would last for between 5100 and 7.8 million years. (Brandon Carter's alternative form of the Doomsday argument was delivered earlier that year, but Gott's derivation was independent.) He made a major effort subsequently to defend his form of the Doomsday argument from a variety of philosophical attacks, and this debate (like the feasibility of closed time loops) is still ongoing. To popularize the Copernicus method, Gott gave The New Yorker magazine a 95% confidence interval for the closing time of forty-four Broadway and Off Broadway productions based only on their opening dates. Education work He received the President's Award for Distinguished Teaching in acknowledgment of his work on the National Westinghouse/Intel Science Talent Search high school student science competition. He is an active promoter of the public awareness of science at the popular level, and Princeton students have voted him the school's outstanding professor several times. Gott was born in Louisville, Kentucky. He is a Presbyterian who distinguishes physical from meta-physical questions by their teleology; he believes that his writings are entirely scientific (not trespassing into