What happens when an unstoppable force collides with an immovable object?

i remember the joker quoting this in the dark knight and this intrigued me since thenWhat happens when an unstoppable force collides with an immovable object?
a mighty big explosion. But seriously there are neither unstoppable forces nor immovable objects. These can be ';approximations';, and in any collision, you would find out which one is a closer approximation. This is a very common expression - like ';between a rock and a hard place';. It is not to be taken literally.What happens when an unstoppable force collides with an immovable object?
The immovable object stays still.


The unstoppable force bounces back and goes in the opposite direction.





It isn't that hard to understand.