When we move relative to spacetime, we experience the effects of gravity and acceleration, which can result in experiencing fictitious forces such as centrifugal force or Coriolis force. These forces arise due to the curvature of spacetime caused by massive objects like planets or stars. In Einstein's general theory of relativity, gravity is not described as a force but rather as the curvature of spacetime caused by the presence of mass and energy.
When we move with spacetime, we are essentially following the natural geodesics or paths dictated by the curvature of spacetime. In this case, we do not experience fictitious forces because we are not accelerating relative to the curved spacetime; rather, we are following the natural paths dictated by the curvature of spacetime.
In circular motion, objects are constantly accelerating towards the center of the circle due to the centripetal force. This acceleration is not due to a fictitious force but rather due to the curvature of spacetime caused by the presence of mass. The object follows the curved path dictated by the curvature of spacetime, and its motion appears to us as circular motion in three-dimensional space. We do not defy the curvature of spacetime in circular motion; rather, we are simply following the natural paths dictated by the curvature of spacetime.
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