The principle that in a group of stratified sedimentary rocks the lowest were the earliest to be deposited.
The principle by which the description of the state of a physical system can be broken down into descriptions that are themselves possible states of the system. For example, harmonic motion, as of a violin string, can be analyzed as the sum of harmonic frequencies or harmonics, each of which is itself a kind of harmonic motion; harmonic motion is therefore a superposition of individual harmonics.
The combination of two or more physical states, such as waves, to form a new physical state in accordance with this principle. See also wave, See Note at Schrödinger.