IRRESISTIBLE FORCE PARADOX

The 'Irresistible force paradox' is a classic paradox formulated as follows:
:''What happens when an irresistible force meets an immovable object?''
Common responses to this paradox resort to logic and semantics.

★ 'Logic:' if such a thing as an irresistible force exists, then no object is immovable, and vice versa. It is logically impossible to have these two entities (a force that cannot be resisted and an object that cannot be moved by any force) in the same universe.

★ 'Semantics:' if there is such a thing as an irresistible force, then the phrase ''immovable object'' is meaningless in that context, and vice versa, and the issue amounts to the same thing as asking, ''e.g.,'' for a triangle that has four sides.
This paradox is a form of the omnipotence paradox, but that paradox is most often discussed in the context of God's omnipotence (''Can God create a stone so heavy that He cannot lift it?'').
The paradox should be understood as an exercise in logic, not as the postulation of a possible reality. According to modern scientific understanding, there are not and indeed cannot be either irresistible forces or immovable objects. An immovable object would have to have infinite inertia and therefore infinite mass. Such an object would collapse under its own gravity and create a singularity. An irresistible force would imply an infinite energy, which by Albert Einstein's equation ''E = mc²'' is equivalent to an infinite mass. Note that, in the modern view, a cannonball which cannot be deflected and a wall which cannot be knocked down are both types of the same (impossible) object: an object with infinite inertia.
An example of this paradox in non-western thought can be found in the origin of the Chinese word for paradox (). This term originates from a story (see the ''Kanbun'' example) in the 3rd century BC philosophical book ''Han Feizi''.^[1]. 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".

Contents

Solutions

The irresistible force paradox in popular culture

References

Solutions

Many possible solutions have been proffered, including one that has the immovable object never moving and the irresistible force never stopping; the irresistible force becomes exponentially slower forever, in order to avoid violating the trait of the immovable object, and so the two never actually collide. A similar solution has the two objects pass through one another, so the force never stops and the object never moves. One criticism of this solution is that it violates the object's immovability, if it is accepted that part of the object must move out of the way of the unstoppable force.
An explanation which seeks to allay this criticism is as follows:
Since the 2 objects directly contradict each other's existence, they can not exist at the same time. Thus each object is slightly out of phase of each other. Though it seems the unstoppable force passes through the immovable object, they do not make physical contact.
Neither of the above is a real solution, as the question is "What happens when an irresistible force ''meets'' an immovable object?" (where "meets" is understood to mean "collides with", perhaps the only definition which yields an interesting question).
Another idea is that the irresistible force will remove a piece from the immovable object or the irresistible force will deflect similar to a light beam on a mirror. Some may maintain that as both have equal physical power (infinity), they will merely cancel each other out and neither will move.
Another approach to this paradox is to simply state that the object will continue to exist, since by definition an irresistible force is an immovable object.
A much simpler answer is that the irresistible force ricochets off the unmovable object. Although it is implied that the irresistible force is traveling in a straight line, it does not state that it must continue moving in the same direction.
Another solution, that the event in question is a contradiction, avoids any paradox. If there exists an irresistible force, there is no immovable object, and vice-versa.

The irresistible force paradox in popular culture

In sports, these terms are commonly used to describe a game when a high-powered offense meets an excellent defense.
The Johnny Mercer song Something's Gotta Give contains the lyric "when an irresistible force such as you/meets an old immovable object like me"
In a ''Knight Rider'' episode (Trust doesn't Rust), the paradox is wrongly attributed to Zeno of Elea and its meaning is intentionally distorted.
This paradox was popularized by pro wrestling play-by-play announcer Gorilla Monsoon in the 1980s with reference to World Wrestling Federation nemeses Hulk Hogan (the irresistible force) and André the Giant (the immovable object).
A variant of the paradox appears in the novel Walking on Glass by Iain Banks, where the solution is: "the immovable object moves; the unstoppable object stops."
Another answer is given in a Mensa puzzle book by Victor Serebriakoff (the former head of MENSA): by allowing the two to come together, a realistic answer that matches the semantics of the question is "an inconceivable event".
In World of Warcraft, when a player gets exalted reputation with the Alterac Valley battleground, among the rewards are The Unstoppable Force (a two-handed mace) and The Immovable Object (a shield). While they are specifically made for player versus player combat, they have no special properties contradicting each other, so the paradox itself is not addressed in-game.
In the World of Warcraft Trading Card Game, the aforementioned pieces of equipment (The Unstoppable Force and The Immovable Object) are portrayed as cards, both sporting powers that destroy both The Unstoppable Force and The Immovable Object. The flavor text of The Immovable Object is "What happens when..." and the flavor text of The Unstoppable Force is "Oh. So that's what happens."
Jarvis Cocker references the paradox (in a sexually suggestive way) in the Pulp song "Seductive Barry" (on the album ''This Is Hardcore''), concluding that "when the immovable (or unmovable) object meets the unstoppable force, there's nothing you can do about it." Many lyrics websites misquote him as saying "unbelievable object".
In the comic All Star Superman, Lois is threatened with death by the Ultra-Sphinx. To save her, Superman must answer the Ultra-Sphinx's question correctly: "What happens when the unstoppable force meets the immovable object?" He thinks for a moment, and then correctly answers: "They surrender".
The tagline of the 1988 movie ''Bulletproof'' is "An unstoppable force is about to meet an unmovable object!"
In the movie Imagine Me & You, the question is asked by the young girl called H. Heck doesn't have an answer, but Luce gives the logic response, as seen above.
In Marvel Comics's X-men title, the Juggernaut is the irresistable force to the Blob's immovable object. An alternate version involves the Hulk as the immovable object; however, it has been established that the Hulk is the stronger of the two, because while Juggernaut's limits are physical, the Hulk's are limited only by his emotion, and there is no limit to the mind.
In , the former King of Prosecutors award was a halberd and a shield, based off an old Chinese tale of a man who presented the king with a halberd that could slice through any shield, and a shield that could block any attack. The king noted the contradiction, which became a symbol for the Prosecutor's Office.

References

1. ''Han Feizei'' (韓非子), chapter 36, ''Nanyi'' (難一 "Collection of Difficulties, No. 1")'.