>If you naively apply Newton's force of gravity, between two masses at a distance, Fg = Gm1m2/d^2, you get an infinite force when a marble (mass 1) is at the ce

>If you naively apply Newton's force of gravity, between two masses at a distance, Fg = Gm1m2/d^2, you get an infinite force when a marble (mass 1) is at the center (distance = 0) of a planet (mass 2) and, for the people who might not have been exposed to the idea in a physics class, that marble at a distance from the planet has a potential energy, energy it would give up were it to be released and allowed to fall toward the planet. But, if instead you did work against the gravity to pull the marble farther away from the planet, that work would be saved up as an increase in the marble's potential energy. And that would continue till you pulled the marble infinitely far away, at which point the force of attraction would be 0 and the marble's potential energy would be zero. The only way this works is if the potential energy of the marble is a negative number, in which case maybe the singularity isn't such a bad idea