Relativity: Einstein's theory of special relativity in multimedia tutorial. The introductory level takes 10 minutes, but has links to over 40 explanatory pages giving greater depth and detail. Einstein Light has a simple introduction to Galilean relativity, electromagnetism and their incompatibility; it explains how Einstein's relativity resolves this problem, and develops time dilation, length contraction and other consequences of relativity for our ideas of time, space and mechanics, including the twin paradox and E=mc2.