The Irresistible force paradox, also the unstoppable force paradox, is a classic paradox formulated as "What happens when an unstoppable force meets an immovable object?" This paradox is a form of the omnipotence paradox[1], which is a simple demonstration that challenges omnipotence: ("Can God create a stone so heavy it cannot be lifted, not even by God Himself?"). The immovable object and the irresistible force are both implicitly assumed to be indestructible, or else the question would have a trivial resolution ("it destroys it"). Furthermore, it is assumed that they are two separate entities, since an irresistible force is implicitly an immovable object, and vice versa. Another common answer is: "The former is consumed by the latter, with an immeasurable release of heat"
The apparent paradox arises because it rests on two premises—that there exist such things as irresistible forces and immovable objects—which cannot both be true at once. If there exists an irresistible force, it follows logically that there cannot be any such thing as an immovable object, and vice versa.
According to modern science, no force is completely irresistible, and there are no immovable objects and cannot be any, as even a minuscule force will cause a slight acceleration on an object of any mass. An immovable object would have to have an inertia that was infinite, and therefore infinite mass. Such an object would collapse under its own gravity and create a singularity and a black hole. An unstoppable force would require infinite energy, which does not exist in a finite universe.
In the physical realm the infinite force will not move out quarks from Quark confinement. In philosophical realm there is no force to move everything since the force by definition belongs also to everything.
An example of this paradox in non-western thought can be found in the origin of the Chinese word for paradox (Chinese: 矛盾; pinyin: máodùn; literally "Spear-Shield"). This term originates from a story (see the Kanbun example) in the 3rd century BC philosophical book Han Feizi.[2] In the story, a man was trying to sell a spear and a shield. When asked how good his spear was, he said that his spear could pierce any shield. Then, when asked how good his shield was, he said that it could defend from all spear attacks. Then one person asked him what would happen if he were to take his spear to strike his shield; the seller could not answer. This led to the idiom of "zìxīang máodùn" (自相矛盾), or "self-contradictory". Another ancient and mythological example of this theme can be found between the Teumessian fox, who's destined to never being caught, and the hound Laelaps, who never misses what it hunts. Realizing the paradox, Zeus turns both creatures into static stars.