principle of equivalence

The principle of equivalence states that locally, the effects of gravity are indistinguishable from acceleration. In simple terms, experiencing gravity (like standing on Earth) feels the same as being in a spacecraft accelerating through space at a certain rate. For example, in a small, enclosed room, you can't tell if the force you're feeling is due to gravity or the room's acceleration. This idea helps scientists understand how gravity works and led to Einstein's theory of general relativity, suggesting that gravity is not just a force but the curvature of spacetime caused by mass and energy.