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The '''curvature of spacetime''' is what gives rise to the "fictitious forces" that are perceived as gravity under [[General_theory_of_relativity|General Relativity]].

The '''curvature of spacetime''' is the theoretical construct of what gives rise to the "fictitious forces" that are perceived as gravity under [[General_theory_of_relativity|General Relativity]].

 

More than one thinker has cautioned that spacetime is not necessarily something that one can ascribe a separate existence to.

It's necessary to define the terms carefully here.  A "fictitious force" is a perceived force on a body in the absence of any visible agent pushing on it.  Examples are the centrifugal force and the Coriolis force.  These forces all have the property that they are exactly proportional to the object's mass.  With careful analysis under Netwtonian/Galilean physics, it's not hard to see why.  The "force" arises from the acceleration of the frame of reference.  Gravity also satisfies the criterion of being exactly proportional to mass—this is Einstein's "equivalence principle".

It's necessary to define the terms carefully here.  A "fictitious force" is a perceived force on a body in the absence of any visible agent pushing on it.  Examples are the centrifugal force and the Coriolis force.  These forces all have the property that they are exactly proportional to the object's mass.  With careful analysis under Netwtonian/Galilean physics, it's not hard to see why.  The "force" arises from the acceleration of the frame of reference.  Gravity also satisfies the criterion of being exactly proportional to mass—this is Einstein's "equivalence principle".