equivalence principle

noun

, Physics.

1. (in relativity) the principle that, in any small region of space-time, the effects of a gravitational field are indistinguishable from those of an appropriate acceleration of the frame of reference.

equivalence principle

/ ĭ-kwĭv′ə-ləns /

1. A principle central to General Relativity stating that a gravitational field is locally indistinguishable from the effects of inertial forces. For example, according to the equivalence principle, it is impossible for someone in a box who experiences a force pushing him to the bottom of the box to know, from the force alone, whether that force is the result of a gravitational field (the box is standing on the surface of a planet) or an acceleration (the box is being pushed by a rocket).

Word History and Origins

Origin of equivalence principle¹

First recorded in 1915–20

Example Sentences

Nuclear clocks could also test a foundation of Einstein’s gravity theory — the equivalence principle.

From Science News For Students

In confirming Galileo’s gravity experiment yet again, the result upholds the equivalence principle, a foundation of Albert Einstein’s theory of gravity, general relativity.

From Science News

The experiment found that the type of atom made no difference to the outcome, perfectly in line with the equivalence principle.

From The Daily Beast