A new kind of camera, which allows you to take the photo now, and focus later at any point you like. There is demo in the web.

The principle is that, you record not the sum of all the light cones, but the individual light ray's vector direction. So that you can focus to any plane by ray tracing method.

44 Challenging problems. Many are quite difficult, and tests if your physics understand is solid enough!

A gnome style to make eclipse and other applications look more compact, and save more screen space.