equivalence principle

American  

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.

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equivalence principle Scientific  

/ 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).

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Etymology

Origin of equivalence principle

First recorded in 1915–20

Example Sentences

Until now, however, nobody had tested whether the equivalence principle holds for matter and antimatter.

From Science Magazine • Sep. 27, 2023

But for the Unruh effect, it’s a matter of acceleration—which is, per Einstein’s equivalence principle, gravity’s mathematical equal.

From Scientific American • May 20, 2022

The accelerations of the two bodies differ by no more than 2.6 parts per million, in agreement with the equivalence principle.

From Nature • Jul. 3, 2018

That "equivalence principle" now serves as the cornerstone of Albert Einstein's theory of gravity, general relativity, and physicists are keen to test it in as many ways as they can.

From Science Magazine • Sep. 7, 2017

This idea that free fall is indistinguishable from, and hence equivalent to, zero gravity is called the equivalence principle.

From Textbooks • Oct. 13, 2016