PBS
Pbs Learning Media: Sagan on Time Travel
Astronomer Carl Sagan discusses the possibility of time travel in this audio-enhanced interview from the NOVAWeb site.
University of New South Wales (Australia)
University of New South Wales: Einstein Light
Einstein Light highlights the Theory of Special Relativity and related topics. Learn how Galileo, Maxwell, and Einstein contributed to our knowledge of relativity, electricity, magnetism, and time by watching fun, interactive modules.
Stanford University
Stanford University: Conventionality of Simultaneity
This site from Stanford University is on the topic of simultaneity in relativity.
Nobel Media AB
The Nobel Prize: Relativity
After a brief introduction, this site provides information on special relativity include sections such as The Michelson-Morley Experiment, The Postulates of Special Relativity, Lorentz Transformations, The Twin Paradox, Energy is...
Massachusetts Institute of Technology
Mit: Open Course Ware: Courses: Physics: Introduction to Special Relativity
College-level electrical physics course highlighting Einstein's Special Theory of Relativity. Course introduces the physics of Lorentz contraction, time dilation, the "twin paradox", and E=mc2. Course features suggested readings,...
American Association of Physics Teachers
Com Padre Digital Library: Open Source Physics: Twin Paradox Program
This model permits manipulation of variables in order to observe the effects of time dilation on twin objects, one moving and one not, as shown in a spacetime diagram.
Other
Uc Riverside: Twin Paradox
To make sense of this, you have to first see the Twin Paradox: Introduction, which is the special relativity version and is linked to this page. This general relativity explanation views the paradox from a gravitational point of view.
Other
Uc Riverside: Usenet Relativity Faq
A physics usenet listing of frequently asked questions relating to relativity, answered by a number of scientists. Administrivia and Reference, Speed of Light, Special Relativity, General Relativity and Cosmology, Black Holes. Loads of...