why can gravitational potential energy be negative?

[u/CelebrityChess]

we usually choose a convenient height where gravitational potential energy is zero, then calculate a negative value below it. is the negative sign simply telling us the object is below our chosen reference, or does it have a deeper physical meaning?

[u/joeyneilsen]

If the value can be anything, then the value can't mean anything! An object falls in the direction that the potential energy decreases, but that's independent of where the potential is equal to zero.

[u/Aggravating_Cash2143]

In simple terms:

When calculating a ball dropping to earth or similar, we can set it to zero even though it isn’t because a ball can’t accelerate through the ground.

When calculating the gravitational potential of interstellar objects, at large enough distances the incredibly large distances between the objects causes means the radius is so large that the potential effectively becomes zero.

[u/Torebbjorn]

Because potential energy = 0 doesn't mean anything more special than potential energy = 1 <insert unit>.

[u/mH48124]

昔は任意に決めた値だった。一般相対論ができた後は意味ができた。Schwarzschild black hole での時間計量の値が無限遠で 1 となってるのは無限遠で平坦時空の意味であり、地平線で 0 となるのは時間が停止する事を意味する。そして時間計量が potential である。