unprimed letter
1Special relativity — (SR) (also known as the special theory of relativity or STR) is the physical theory of measurement in inertial frames of reference proposed in 1905 by Albert Einstein (after considerable contributions of Hendrik Lorentz and Henri Poincaré) in the …
2nature, philosophy of — Introduction the discipline that investigates substantive issues regarding the actual features of nature as a reality. The discussion here is divided into two parts: the philosophy of physics and the philosophy of biology. In this… …
3Cardinal point (optics) — For other uses, see Cardinal point (disambiguation). In Gaussian optics, the cardinal points consist of three pairs of points located on the optical axis of an ideal, rotationally symmetric, focal, optical system. For ideal systems, the basic… …
4Graffiti terminology — A number of words and phrases have come to describe different styles and aspects of graffiti. Like all slang and colloquialisms, the phrases vary in different cities and countries. The following terminology comes primarily from the United… …
