The science behind science fiction

This is a really interesting set of articles. Most of it I already know, but it's presented in an approachable format, and it's especially nice for those of you who sometimes feel overwhelmed by hard science fiction.

http://www.netspace.net.au/~gregegan/FOUNDATIONS/index.html

"Foundations is a series of articles, first published in the magazine Eidolon, on some of the theories of twentieth-century physics that have most influenced modern science fiction. However, these are not essays on the history or philosophy of science; their aim is to show how the central idea of each theory leads to detailed, quantitative predictions of real physical effects. For example, the article on special relativity derives formulas for time dilation, Doppler shift, and aberration."