User blog comment:Annabeth and Percy/Ask A&P anything/@comment-15860919-20160102030655/@comment-26402117-20160102185337

We can assume that our unstoppable force has infinite force and our immovable object has infinite mass. The object has infinite mass in a certain space tho? - that would tear a hole in timespace with the gravitational force and pretty much destroy the universe in a giant quasar. The force is infinite - it can transfer infinte energy in a certain time (because energy = force times distance). Both entities break the laws of physics.

 I've got a mechanical explanation if we ignore these details tho. ''Lets think of this from a physical perspective. If momentum is both the product of force with time - and mass with velocity., we are free to assume that the infinite force is a contact force like tension. We set up an equation m.dv=F.t, thus we sub in infinite mass and force and we get movement. But that is the tension without the reactionary force - momentum is conserved so the object would exert an force back that is infinite (due to its infinite mass and finite acceleration where F=ma) and stay in the same place. This is all hypothetical disprovable crap - but its based on real formulas.''