This well-organized site, an excellent introduction to time travel, is designed for people with various levels of scientific knowledge. The site includes some of the mathematics that may support time travel as well as information on black-hole theory and the theory of relativity.

This site offers virtual trips via MPEG movies to neutron stars and black holes. Most movies are accompanied by a written description. The site also offers plenty of GIFs, a FAQ page, and links to other astronomy sites.

This intriguing site offers authoritative studies on the history and philosophy of time, the physics of time travel, and experiments in time travel. Gain access to the Tri Star System, the world's largest information database of science, technology, and research related to time travel, and shop for time-travel-related products in the on-line store.

This page offers a paper that discusses the possibilities of time travel and covers the subjects of time dilation, wormholes, and the grandfather paradox.

This site further develops the theory of time travel. It examines some of the basic principles of quantum physics, including the theory of elementary waves.

In a book the Wall St. Journal called an "engrossing blend of theory, history, and anecdote," Kip Thorne, the Feynmann Professor of Theoretical Physics at the California Institute of Technology, discusses everything from black holes to wormholes, with the final chapter devoted to time travel. The book's glossary is excerpted in Timespeak.

Pickover, the lead writer for Discover Magazine's brain-boggler column, eases the reader into the arcane theory behind time travel with amusing fictional narratives, in which two people in a Museum of Music in New York experiment with time. See Traveling Through Time for an excerpt.

Physics and the nature of time conveyed with the remarkable wit, clarity, and patience of the foremost theoretical physicist since Einstein. Illustrated with striking color imagery.

Paul Nahin doesn't write like an engineering professor, but that's what he is (at the University of New Hampshire). With often amusing references to novels, comics, and sci-fi films, Nahin takes on the daunting topic of time machines with erudition and flair.

In his latest work, James Gleick explores our increasingly speed-driven world. He specifically investigates the newest paradox of time: as technology accelerates, offering more time-saving devices, the notion of haste only increases. From atomic clocks, to answering machines, to the bunkers of war, Gleick approaches the subject from diverse perspectives.