the simplest way to describe it is that an object in freefall moves in geodesic in spacetime, which is a is not straight line in 3dimensional classical physics

the simplest way to describe it is that an object in freefall moves in geodesic in spacetime, which is a is not straight line in 3dimensional classical physics but produces gravitational motion. https://en.wikipedia.org/wiki/Geodesics_in_general_relativity https://en.wikipedia.org/wiki/Geodesics_in_general_relativit... The basic idea is that depending on your frame of reference, you might experience what is called a fictitious or psuedo force that disappears in a more simple frame of reference. Examples of these include centrifugal force, the Coriolis effect. https://en.wikipedia.org/wiki/Fictitious_force https://en.wikipedia.org/wiki/Fictitious_force Einstein's great revelation in the theory of general relativity was that there was no difference between gravity and free fall - which is called the equivalence principle. https://en.wikipedia.org/wiki/Equivalence_principle https://en.wikipedia.org/wiki/Equivalence_principle In special relativity, einstein's theory had a preference for inertial frame observers where the observer essentially became the origin of coordinate system to map space by, but in general relativity einstein does away with inertial frames as privileged, and an observer is literally decided by what light it can see, and their coordinate system cannot be universal because of curved space. https://en.wikipedia.org/wiki/Inertial_frame_of_reference#Special_relativity https://en.wikipedia.org/wiki/Inertial_frame_of_reference#Sp... https://en.wikipedia.org/wiki/Observer_%28special_relativity%29 https://en.wikipedia.org/wiki/Observer_%28special_relativity...