Equivalence principle

Definition

The equivalence principle states that the effects of gravity are indistinguishable from the effects of acceleration. It underpins general relativity by suggesting that an observer in free fall experiences no gravitational field.

5 Must Know Facts For Your Next Test

1. The equivalence principle was formulated by Albert Einstein.
2. It implies that locally (in a small enough region of spacetime), the laws of physics in a freely falling reference frame are identical to those in an inertial frame without gravity.
3. There are two forms: the weak equivalence principle and the strong equivalence principle.
4. The weak equivalence principle states that all objects fall at the same rate in a gravitational field, regardless of their mass or composition.
5. The strong equivalence principle extends this idea to include all physical laws, not just mechanical ones.

Review Questions

• What is the key idea behind the equivalence principle?
• How does the weak equivalence principle differ from the strong equivalence principle?
• Why is the equivalence principle important for general relativity?

Related terms

General Relativity:

A theory of gravitation developed by Albert Einstein, describing gravity as a property of curved spacetime caused by mass and energy.

Inertial Frame: A reference frame in which an object not acted upon by forces moves at constant velocity.

Free Fall: The motion of an object where gravity is the only force acting upon it, making it appear weightless.