# Ball goes up again due to curvature of spacetime

rajeshmarndi
A ball thrown up comes down again because the ball follows the curvature of spacetime. So is it possible that the ball comes down and before hitting the surface, goes up again due to curvature of the spacetime,which now point upward.

Mentor
curvature of the spacetime,which now point upward

Why would the curvature point upward?

Mentor
A ball thrown up comes down again because the ball follows the curvature of spacetime. So is it possible that the ball comes down and before hitting the surface, goes up again due to curvature of the spacetime,which now point upward.

Sure, if you can arrange to curve spacetime in such a way that the curvature carries the path of the ball away from the surface of the earth. You could do that by arranging to fix a mass much larger than that of the Earth directly overhead. You don't even need any general relativity to do this, ordinary classical Newtonian gravity will describe this (completely impractical and unrealistic) setup just fine.

But if the Earth is the only large mass in the area, the curvature will be such that the ball's path heads towards the center of the earth. Mass and energy are what curves spacetime, so you won't get a different curvature unless you introduce another large mass into the picture.

rajeshmarndi
Why would the curvature point upward?

Like in the picture, if the toy car is driven upward, when it goes to the other side, it comes down. Likewise if the line in the picture is high enough, when it can go up and come down, couldn't while it is coming down, couldn't it rise up again.

Also why is that the ball thrown vertical, always remain overhead us and do not go ahead from us in the curve path.