# Immoveable V Unstoppable **URL:** \ **Category:** Great Debates\ **Created:** [November 24, 2008, 1:02pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238 "2008-11-24T13:02:04Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [November 24, 2008, 9:42pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/61 "2008-11-24T21:42:42Z")
> [@Pleonast](#): > > Whether there is a problem with the signs depends on the answer to “is it possible for the Strong Man to attempt to life the Heavy Lady?” If your statement “they do not interact and have in fact never even met” is extended with “and never will meet”, then it is impossible for them to interact. And there is no contradiction. No one has or will ever succeed in lifting her, and he has not and never will fail to lift anybody. Let’s say they never will meet. Are both signs then true? ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [November 24, 2008, 10:05pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/62 "2008-11-24T22:05:30Z")
> [@Strassia](#): > > This comes back to the difference between unstoppable object and an irresistable force. Your example works on the second, but not the first. You could, logically, have both The Heavy Lady (“No one can push her aside!!”) an The Slippery Ell (No one can hold him in place!!"). All the eel has to do is go between her legs and no contradiction in logic. That’s all good and fine, but that’s not my example. Do you see a logical problem with the signs in my example? ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [November 24, 2008, 10:06pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/63 "2008-11-24T22:06:19Z")
> [@Strassia](#): > > Not to nitpick, but it depends on how you define object. Is a photon an object? What about an electron? To me an object is something that exists and is defined. Mass, charge, energy; all attributes of objects, but not required to make the object exist. Interesting point, but I think the accepted definition of an object here is something that has mass. Otherwise, that’s like saying “Picture an unstoppable object made of photons, and an immovable object made of gravitons…” Huh? > [@Strassia](#): > > That may be a valid solution, depending on the framing of the question. Does “unstoppable” mean unchanging speed(scalar, direction does not matter) or velocity (vector, direction does matter) Exactly. That’s why there’s no real answer besides the one we know to be: _The question, while on the surface is interesting, is ultimately meaningless._ ---
**Author:** ![pancakes3](https://avatars.discourse-cdn.com/v4/letter/p/ba9def/32.png) [@pancakes3](https://boards.straightdope.com/u/pancakes3)\ **Post date:** [November 24, 2008, 10:06pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/64 "2008-11-24T22:06:27Z")
this has quickly become a logic problem and not a science problem, which is starting to twist the constraints established in the OP. However, i don’t think anyone really knows what we’re arguing anyway - a physics problem or a logic problem, so… i guess have at it. the strong-man analogy is flawed though. the question isn’t about the two meeting. the question necessitates the two meeting. the question isn’t if the signs are flawed but rather can he lift her? once you ask that, the logic is circular and one must be false. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [November 24, 2008, 10:11pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/65 "2008-11-24T22:11:49Z")
> [@pancakes3](#): > > the strong-man analogy is flawed though. the question isn’t about the two meeting. the question necessitates the two meeting. the question isn’t if the signs are flawed but rather can he lift her? once you ask that, the logic is circular and one must be false. That’s precisely the point. One of the signs must be false. Regardless of whether they ever meet, both can’t possibly be true. The problem isn’t with the science, it’s with mutually exclusive definitions. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [November 24, 2008, 10:17pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/66 "2008-11-24T22:17:01Z")
> [@pravnik](#): > > Let’s say they never will meet. Are both signs then true? As I said, in the post you quoted, there is no contradiction if it’s stipulated they will never meet. > [@pancakes3](#): > > the question necessitates the two meeting. Why must they meet? If, by construction, the man and woman (or ball and pin) will never meet, then it is not logical to ask about their meeting. ---
**Author:** ![Strassia](https://avatars.discourse-cdn.com/v4/letter/s/e8c25b/32.png) [@Strassia](https://boards.straightdope.com/u/Strassia)\ **Post date:** [November 24, 2008, 10:22pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/67 "2008-11-24T22:22:30Z")
> [@pravnik](#): > > That’s all good and fine, but that’s not my example. Do you see a logical problem with the signs in my example? Yes I agree the signs in your example are not logically consistent. If the OP was “What happens when a force that can move any object acts on an object that cannot be moved?”, I would agree with you. I am merely stating that there is a difference between an unstoppable object and an irresistible force, and that a logical framework can be proffered that could contain both an unmovable object and an unstoppable one and still be consistent. > [@cmyk](#): > > Interesting point, but I think the accepted definition of an object here is something that has mass. > > Otherwise, that’s like saying “Picture an unstoppable object made of photons, and an immovable object made of gravitons…” Huh? The problem is you are thinking that objects have to be solid things that you can touch. But solids aren’t(really solid, that is). The reason our fingers do not pass through our keyboards is that there is a force that repels them (electromagnetic). What we call mass is merely the property of exerting gravity. I contend that you can have an object made of photons. A laser beam is an object made of coherent photons traveling together at the speed of light. It has momentum, energy and shape. What about this disqualifies it as an object? > [@](#): > > Exactly. That’s why there’s no real answer besides the one we know to be: _The question, while on the surface is interesting, is ultimately meaningless._ ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [November 24, 2008, 10:41pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/68 "2008-11-24T22:41:34Z")
> [@Pleonast](#): > > As I said, in the post you quoted, there is no contradiction if it’s stipulated they will never meet. So if a kid approaches you at your circus and notes that each sign contradicts the other and asks which one is correct, your response is that they’re both correct so long as they each stay at opposite ends of the midway? The problem isn’t just what happens when they meet, it’s with the descriptions. Each description is worded so as to contradict the other, and both cannot be true. ---
**Author:** ![Captain\_Carrot](https://avatars.discourse-cdn.com/v4/letter/c/f0a364/32.png) [@Captain\_Carrot](https://boards.straightdope.com/u/Captain_Carrot)\ **Post date:** [November 24, 2008, 11:01pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/69 "2008-11-24T23:01:57Z")
> [@Fish](#): > > but if you define “Unstoppable” as “always moves at the same velocity” then Unstoppable could bounce, like light from a mirror. Nitpick: bouncing would change its velocity, since it includes both speed and direction. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [November 24, 2008, 11:02pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/70 "2008-11-24T23:02:57Z")
> [@pravnik](#): > > So if a kid approaches you at your circus and notes that each sign contradicts the other and asks which one is correct, your response is that they’re both correct so long as they each stay at opposite ends of the midway? The problem isn’t just what happens when they meet, it’s with the descriptions. Each description is worded so as to contradict the other, and both cannot be true. Both cannot be true, if they could interact with each other. But unless you can prove that that hypothetical is always satisfied, you cannot assume it. If we know it is impossible for them to meet, then there’s no contradiction because it’s nonsensical to ask “what happens when the Strong Man tries to lift the Heavy Woman?” If you want to appeal to the real world and say it’s silly to say the could never meet, that’s fine. But then you need to add an axiom that “all objects/forces can potentially interact”. Once you include that axiom, then it is logically contradictory to have both the Strong Man and Heavy Woman. But you need that axiom. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [November 24, 2008, 11:24pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/71 "2008-11-24T23:24:16Z")
> [@Pleonast](#): > > Both cannot be true, if they could interact with each other. But unless you can prove that that hypothetical is always satisfied, you cannot assume it. > > If we know it is impossible for them to meet, then there’s no contradiction because it’s nonsensical to ask “what happens when the Strong Man tries to lift the Heavy Woman?” > > If you want to appeal to the real world and say it’s silly to say the could never meet, that’s fine. But then you need to add an axiom that “all objects/forces can potentially interact”. Once you include that axiom, then it is logically contradictory to have both the Strong Man and Heavy Woman. But you need that axiom. The descriptions I’ve given in the signs don’t make that distinction. Each flatly states that the other is false. The Strong Man’s sign doesn’t claim “the Strong Man can lift any person in the world so long as he doesn’t try to lift the Heavy Lady,” they say he is capable of lifting any person in the world, bar none. If there is one person in the world he is incapable of lifting his sign is incorrect, and the Heavy Lady’s sign makes exactly that claim. Even if they never, ever meet, their descriptions are mutually incompatable and logically irreconcilable. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [November 24, 2008, 11:35pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/72 "2008-11-24T23:35:20Z")
> [@pravnik](#): > > The descriptions I’ve given in the signs don’t make that distinction. Each flatly states that the other is false. The Strong Man’s sign doesn’t claim “the Strong Man can lift any person in the world so long as he doesn’t try to lift the Heavy Lady,” they say he is capable of lifting any person in the world, bar none. If there is one person in the world he is incapable of lifting his sign is incorrect, and the Heavy Lady’s sign makes exactly that claim. Even if they never, ever meet, their descriptions are mutually incompatable and logically irreconcilable. Except we know that it is impossible for them to meet. It’s a fact of this scenario. “Any person in the world” has been defined to exclude the other circus performer. So the signs do not contradict each other. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [November 24, 2008, 11:48pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/73 "2008-11-24T23:48:35Z")
> [@Pleonast](#): > > Except we know that it is impossible for them to meet. It’s a fact of this scenario. “Any person in the world” has been defined to exclude the other circus performer. So the signs do not contradict each other. Both are universal, unqualified claims. Any person in the world means exactly that, or the claim is meaningless. Let’s make the example a little clearer: the Strong Man’s sign explicitly says that he is capable of lifting any person in the world, including the Heavy Lady. The Heavy Lady’s sign says no person in the world is capable of lifting her, including the Strong Man. One must be false. If you’re saying both can be true so long as the rules of nature mandate that they never meet, you’re basically arguing that both can’t exist in the same universe, which was exactly the point all along. ---
**Author:** ![The\_Man\_In\_Black](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@The\_Man\_In\_Black](https://boards.straightdope.com/u/The_Man_In_Black)\ **Post date:** [November 24, 2008, 11:52pm UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/74 "2008-11-24T23:52:13Z")
So, what would happen if The Juggernaut ran head on into Superman? ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [November 25, 2008, 12:08am UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/75 "2008-11-25T00:08:09Z")
> [@pravnik](#): > > Both are universal, unqualified claims. Any person in the world means exactly that, or the claim is meaningless. It’s illogical to claim “any person” includes both the Strong Man and Heavy Lady when you’ve specified that they can never meet. “Any person” must implicitly mean “any possible person” or else it is logically meaningless. Would you also accept that “any person” includes people that don’t actually exist? Can the Strong Man lift Santa Claus? Can Santa Claus lift the Heavy Lady? Those are as nonsensical as “can the Strong Man lift the Heavy Lady?” “Any” must have a precise meaning, and in this scenario, we’ve stipulated that it does not include the performers. > [@](#): > > Let’s make the example a little clearer: the Strong Man’s sign explicitly says that he is capable of lifting any person in the world, including the Heavy Lady. The Heavy Lady’s sign says no person in the world is capable of lifting her, including the Strong Man. One must be false. In that case, both signs are false, because we cannot say anything meaningful about their meeting, since we have defined their meeting as impossible. But the it would still be true that “the Strong Man can lift any person” and “the Heavy Lady cannot be lifted by any person”. > [@](#): > > If you’re saying both can be true so long as the rules of nature mandate that they never meet, you’re basically arguing that both can’t exist in the same universe, which was exactly the point all along. The rules of nature do not change whether something is logical or not–that is decided from first principles. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 25, 2008, 12:11am UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/76 "2008-11-25T00:11:52Z")
> [@pravnik](#): > > Both are universal, unqualified claims. Any person in the world means exactly that, or the claim is meaningless. Let’s make the example a little clearer: the Strong Man’s sign explicitly says that he is capable of lifting any person in the world, including the Heavy Lady. The Heavy Lady’s sign says no person in the world is capable of lifting her, including the Strong Man. One must be false. If you’re saying both can be true so long as the rules of nature mandate that they never meet, you’re basically arguing that both can’t exist in the same universe, which was exactly the point all along. I agree - imposing the non-meeting condition is just rendering the definitions completely trivial. _Any_ force could then be considered an unstoppable force, and any object could be considered immovable. ---
**Author:** ![Johnny\_Q](https://avatars.discourse-cdn.com/v4/letter/j/898d66/32.png) [@Johnny\_Q](https://boards.straightdope.com/u/Johnny_Q)\ **Post date:** [November 25, 2008, 12:15am UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/77 "2008-11-25T00:15:55Z")
There’s nothing that says the Unstoppable force can’t be deflected rather than absorbed by the Immovable object. The Force keeps moving and the Object stays still. More likely, one of the two would turn out to be as immovable/unstoppable as advertised. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [November 25, 2008, 12:28am UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/78 "2008-11-25T00:28:52Z")
[QUOTE=Strassia] Yes I agree the signs in your example are not logically consistent. If the OP was “What happens when a force that can move any object acts on an object that cannot be moved?”, I would agree with you. I am merely stating that there is a difference between an unstoppable object and an irresistible force, and that a logical framework can be proffered that could contain both an unmovable object and an unstoppable one and still be consistent. [/QUOTE] But only, it seems to me, by stipulating non-interaction, which is the same thing as having the body builder never meet the heavy lady. > [@Mangetout](#): > > I agree - imposing the non-meeting condition is just rendering the definitions completely trivial. _Any_ force could then be considered an unstoppable force, and any object could be considered immovable. That’s precisely the point. If I throw the bowling ball out into space, it’s an unstoppable bowling ball as long as I stipulate it doesn’t hit anything. Except, of course, what I’ve implicitly done is defining a universe in which there is nothing to stop the bowling ball, thus making the bowling ball unstoppable. The same goes for the bowling ball orbiting the immovable pin. ---
**Author:** ![begbert2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/begbert2/32/3357_2.png) [@begbert2](https://boards.straightdope.com/u/begbert2)\ **Post date:** [November 25, 2008, 12:47am UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/79 "2008-11-25T00:47:26Z")
> [@chowder](#): > > Well lemme think: > > How big? I guess about the size of a cricket ball or baseball…take your pick > > Unstoppable means it’s hurtling through space at a great rate of knots, always in the same direction and always at the same speed. > > Immovable means just that and it was never moving it just appeared at the same time as the unstoppable thingy began its cosmic hurtling. > > Oh and they are both the same size Until I saw this I was going to suggest the option that the unstoppable force _bounces_, retaining speed byt changing direction - which certainly isn’t stopping, but also isn’t this new definition of immoveable. The next option is that they pass through each other - either noninteractively, or with the unstoppable object becoming a cricket-ball shaped cloud of stoppable powder having been thorougly perforated by the particles of the immobile object. Of course, this only works if none of the composite particles directly impacts, which would then be exactly the same problem at a submolecular scale. (The noninteractive collision would still work of course.) A third option is that the immovable object is annihilated - utterly vanishing from existence in a puff of logic, as it were. You can’t do that to the unstoppable object because annihilating it would arguably count as stopping it, but the immobile object doesn’t have that problem, as long as it vanishes without moving. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [November 25, 2008, 12:49am UTC](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238/80 "2008-11-25T00:49:45Z")
In Greek Mythology, this was the same problem as Laelaps the hound (who caught evetrything it chased) and the Teumassian Vixen (who always escaped). Zeus solved the problem by turning them intostone, or into constellations, so that the resolution never occurred: > **[Teumessian fox](https://en.wikipedia.org/wiki/Teumessian_fox)** > > In Greek mythology, the Teumessian fox, or Cadmean vixen, was an enormous fox that was destined never to be caught. > It was said that the Teumessian fox had been sent by the gods (perhaps Dionysus) to prey upon the children of Thebes as a punishment for a national crime. Creon, then-Regent of Thebes, set Amphitryon the impossible task of destroying this beast. He discovered a supposedly perfect solution by using the magical dog Laelaps, who was destined to catch everything it chased, to catch th... [Previous page](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238.md?page=3) [Next page](https://boards.straightdope.com/t/immoveable-v-unstoppable/474238.md?page=5)