General relativity doesn't really say forces don't exist, it just says that they're a secondary, and relative, effect caused by a more fundamental phenomenon, i

General relativity doesn't really say forces don't exist, it just says that they're a secondary, and relative, effect caused by a more fundamental phenomenon, i.e. the curvature of spacetime due to the presence of mass/energy. Just as centrifugal force is a relative effect that you only observe in a rotating (i.e. accelerated) reference frame, the force of gravity is also a relative effect that you only observe in an accelerated reference frame. Standing on Earth, we're accelerating towards the center at 9.8 m/s^2, and we feel that as weight due to a force of gravity that we experience in our reference frame. If you jump out of a plane, though, you feel weightless (especially if you can arrange to do so in a vacuum), because you're in "free fall" - you're following the curvature of spacetime. In your reference frame, you're not experiencing the force of gravity. This demonstrates that gravity, like centrifugal force, is a "fictitious" force - which doesn't really mean that it's not real, but rather that it's a secondary effect that depends on your reference frame.