The principle that the parties in a transaction should be independent and on an equal footing, without any favorable treatment, fiduciary duties, etc.

A method of analysis applied to problems of wave propagation, stating that every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere.

(physics) A conjecture asserting that it is impossible to create paradoxes by time travel because the past cannot be changed.

(physics) Synonym of Ritz's combination principle