You must have heard the anecdote about the apple falling on Newton's head that led him to come up with the concept of Gravity. A long time later, Einstein upgraded it to the General Theory of Relativity as it is today. And it explains gravity on the basis of space geometry. So the question here is how will General Relativity explain Newton's apple?
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Qmechanic
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user346150
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The apple didn't hit Newton on the head. See https://hsm.stackexchange.com/q/13459 – PM 2Ring Oct 14 '22 at 17:26
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1Does this answer your question? Why would spacetime curvature cause gravity? – John Rennie Oct 15 '22 at 05:15
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1I go through the calculation here – John Rennie Oct 15 '22 at 05:18
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The apple starts at rest in a local inertial frame, and since an accelerometer on the apple reads 0 it remains at rest in that frame. The ground also starts at rest in the same local inertial frame, but since an accelerometer on the ground reads 1 g upwards it accelerates upwards at 1 g and pushes Newton's head into the stationary apple.
Dale
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The Earth warps space in a manner similar to a Kerr metric, which has certain geodesics that can be calculated. The apple, being a freely falling object, moves on one of these geodesics until it hits Newton's head.
Allure
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Numerically; relativity cannot explain apple falling by applying suggested relativity equation and expect a number.
Theoretically it trys to give explanation; although both apple and earth are stationary in their frame of reference yet space and time are not stationary.
Since masses/inertia is resistance to motion; objects tends to follow space time curvature to keep space and time stationary to their frame of reference. Since time cannot be hold stationary ; acceleration occures.
Timo Kimo
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