I suppose that point mass has its own gravitational well. Why this point mass is still attracted by other gravitational waves. I expect that this point mass is surrounded by "gravitational hills". Why it is not blind to other weaker gravitational waves?

If we think about gravity in terms of shape of spacetime.

I mean that point mass (left chart) creates "sharp" gravity potential. Lowest gravity potential is exactly where point mass is located. Point stays in place (?).

When mass is spread across spacetime (right chart) this is different. Lowest gravity potential is moved from the centre of the object. Object accelerates.

Does point mass exist in real world?

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closed as unclear what you're asking by ACuriousMind, Kyle Kanos, Ali, Brandon Enright, John Rennie Jul 25 '14 at 5:04

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  • 2
    $\begingroup$ After the edit, I'm still not sure what you are asking: The grav. potential is caused by the point mass. If the points mass moves, for whatever reason, the potential moves as well, so asking "if the point mass moves out of its well" is nonsensical. Whether there are point masses (e.g. perhaps the electron) in the real world seems also to be a bit of an unrelated question. $\endgroup$ – ACuriousMind Jul 28 '14 at 21:55
  • $\begingroup$ Gravitation moves with finite speed. But in the place where "point mass" is gravity will be always actual. Because there is 0 distance. So I agree that it may be not preventing point mass from moving. $\endgroup$ – Pawel Welsberg Jul 28 '14 at 22:06
  • $\begingroup$ Another issue with point mass is that well depth will be infinite. $\endgroup$ – Pawel Welsberg Jul 28 '14 at 22:08
  • $\begingroup$ In question I thought about gravity acting with delay. But now I don't think it works like that. I think question can be deleted. $\endgroup$ – Pawel Welsberg Jul 28 '14 at 22:20

Mathematically, that's due to superposition. Both masses produce some gravitational field, which add together to give the "net field". (The same goes for electromagnetism, where one may add electric/magnetic field strengths,electric potentials etcetera for every point in space.) Ever so slightly changing the field strength at the well. As gravity gets weaker over distance one side of the well should be more affected than the other side, causing attraction as one side has a stronger field(therefore pull) than the other side.

  • $\begingroup$ one side of the well should be more affected than the other side I was thinking about scenario where well walls are vertical (both the same). $\endgroup$ – Pawel Welsberg Jul 28 '14 at 21:42

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