Title text:
Unstoppable force-carrying particles can’t interact with immovable matter by definition.
Transcript:
[An arrow pointing to the right and a trapezoid are labeled as ‘Unstoppable Force’ and ‘Immovable Object’ respectively.]
[The arrow is shown as entering the trapezoid from the left and the part of it in said trapezoid is coloured gray.]
[The arrow is shown as leaving the trapezoid to the right and is coloured black.]
[Caption below the panel:] I don’t see why people find this scenario to be tricky.
Source: https://xkcd.com/3084/
i think I’ve made that game engine before.
Maybe the universe will crash due to division by zero, floating-point error, integer overflow and segmentation fault, all of them occurring simultaneously. The objects will experience infinite velocity and infinite forces, there will be rounding errors, the system will run out of RAM and storage space. The universal CPU will max out all threads, and run out of cooling capacity. The hardware catches fire, the entire universe immediately collapses into a singularity, resulting in a new big bang as the system reboots. Oh, and the log files are corrupted, so good luck troubleshooting that one.
Division by zero is just zero.
Just think about it. You have 4 slices of pie and 0 people to eat any.
How much pie did each of those no people eat. Clearly the answer is just 0.
Education took us for absolute fools.
It’s just as true a statement to say each of those 0 people at a billion slices of pie.
However, with these types of word problems, there’s usually the implication that the pie is now gone. There’s kind of a problem figuring out where the pie went when nobody ate any pie.
This one is a bit counterintuitive. My maths teacher explained it like this. Take a look at this graph. If you approach zero from the positive side, it looks like the line goes to infinity. If you approach zero from the negative side, it appears to go to negative infinity instead.
Is it both, is it zero, is it all the values? The canonical answer is “undefined”. The value of y at x=0 doesn’t have a meaningful answer.
deleted by creator
A popup will appear asking you to buy the “Extended Physics” DLC
First billion years free. After that it’s 17.99 per millennia.
What currency?
I doubt the universe accepts Euro or whatever.
It’s just 17.99. Take it or leave it.
That’s actually how black holes are made
Dammit I should have posted my exact same solution back when I thought of it for the first time, but I was lazy so eh my fuck up
🤯
Pretty sure none of these exist so idk why it bothered any1 in the first place.
if people only bothered to think about things that exist (especially things that they think exist) we would probably go the way of the dodo. funnily enough that would prevent the dodos from going that way but whatever.
I highly recommend watching the Vsauce video on supertasks—it’s a great video as expected from Vsauce but also ends on a great note about people and their tendency to think about things like this.
You clearly haven’t met my mother.
Is the an unstoppable force or an immovable object or a little bit of both?
Neutrinos are pretty close to an unstoppable force: they can pass right through the earth without being stopped.
I believe this is an expectation of dark matter, to being even closer to an unstoppable force. Perhaps a reason we haven’t found it yet would a because we don’t have a detector that can stop it
These kinds of contradicitons exist in man made structures, such as laws, rules and regulations. In situations like that, a judge has to pick which rule to follow and which one to ignore. The first time that happens, it becomes the standard solution (precedent) for those kinds of problems.
It can bother people who believe in omnipotent deities.
So neutrinos?
more specifically, right handed neutrinos (only left handed neutrinos interact)
Facepalm Man i’m dumb, this is a great answer to that thought experiment.
Force is not a thing that moves. Force is what is applied to an object. In this “answer” whatever is shown and depicted as force is not force.
Then reverse the assumptions. Maybe it’s the immovable object that can’t be interacted with. Apply all the force you want and meet nothibg
If you applied the unstoppable force and the object of application did not move - then this force was not unstoppable
Was that unstoppable force unstoppable before the object? Was it unstoppable after the object? Did anything stop it?
Eh, it’s just redefining the assumed meaning. “Intangible” does mean “unstoppable” in a way, but that’s not really what’s intended.
so if god creates rock so heavy that it can’t lift it, its hand just passes through the rock? makes sense.
A rock so heavy you cannot lift it is not an immovable object. Just cause you are weak does not mean you are right.
tell that to god
Dear God,
A rock so heavy you cannot lift it is not an immovable object. Just cause you are weak does not mean you are right.
Kind regards, me
Dear nerd,
Get smote.
God
Joke’s on you, old man! I have a chariot of iron!
I think if God creates a rock so heavy he can’t lift it, it’s probably a black hole. By definition we can’t know what happens inside a black hole, because no information escapes the event horizon. As it’s now consistent with known physics that we can’t know many aspects of this interaction between God and the black hole, I think this paradox is basically solved. We don’t know any more about the interaction, but it’s no longer a paradox, it’s consistent with physics.
Actually, the new theory is that the hawking radiation exfiltrates information from inside the black hole via quantum entanglement. Of course, it hasn’t been tested yet for obvious reasons.
But black holes have finite mass. By “heavy” you’re implying it’s infinitely heavy or something.
You can definitely also lift a black hole.
Well I don’t know about any objects more massive than black holes. I think a black hole is really the only viable form a body can take once there’s enough matter in one place, like there’s an upper limit for the size of stars and after that anything larger collapses into a black hole.
An object of infinite mass is a contradiction, a universe can’t exist with a single object of infinite mass, it would consume everything instantly.
OK, but being very massive is not the same as what was being discussed.
You can also “lift” a finitely massive black hole with anything else massive.
OK, but being very massive is not the same as what was being discussed.
Are you sure? I mean the word “heavy” was what I was going on, but there is a distinction I suppose.
You can also “lift” a finitely massive black hole with anything else massive.
Yeah, that’s true… But again, I do have to stress that there is no alternative to “finitely massive” you really can’t have an object of infinite mass in our universe.
Edit: So I guess it comes down to this: If “lift” and “move” are synonymous, then anyone can move any object of finite mass. An object of infinite mass can’t exist in this universe. So you could say that the answer to the question is definitively no, God can’t create a rock so big that he couldn’t lift it, at least not given the laws of physics in this universe as he created it. (For this conjecture we’re assuming God exists and created the universe).
If God created this universe he could in theory also create other universes with different laws of physics. So in that case, sure, why not, who knows.
It may be worth it to decide how we define ‘unstoppable force’ and ‘immovable object’.
An Immovable Object has 0 velocity:
v = 0
Acceleration is the time derivative of velocity:
a = d/dt(v(t))
a = d/dt(0)
a = 0
And we know that
a = Fnet / m
An object with infinite mass would satisfy this equation, but an object with no net force would too. We could add a correction force that will satisfy the constraint of 0 net force.
|Fnet| = 0
∑Fi = 0
Fcorrection + … = 0
To satisfy Newton’s 3rd law, we would need a reaction force to our correction force somewhere, but let’s not worry about that for now.
A physics definition of ‘Unstoppable Force’ is:
|Funstoppable| =/= 0
In this case the gravitational force fits this description, given a few constraints
Fg = Gm∑ Mi / xi2
As long as the gravitational constant G is not 0, our object has mass, and
∑ Mi / xi2 =/= 0, then
|Fg| > 0
But this does feel kinda like cheating because it’s not really what people mean by ‘unstoppable force’. the other way to define it is just immovable object in a different reference frame.
a = 0, |v| > 0
I’m gonna stop here because this is annoying to type out on mobile
God is distinct from the creation and has no physical shape inside the creation so the idea of “object too heavy to lift” is already conceptually nonsensical.
But also in the scope of our physics: What would an object be that is too heavy to “lift” for anyone and anything? It would be the heaviest object in the universe. So what will happen with the heaviest object in the universe? It would be the main center of gravity for everything else. In the same way you cannot “lift” the earth, but rather lift yourself from it as your force will just propel you away from the earth rather than the earth away from you, while you are inside the area dominated by earths gravitational field.
When you jump you are pushing the earth away from yourself a little bit, and then some of your gravity pulls the earth back toward you. You have moved the earth, and for a brief moment your jump has in fact altered Earth’s orbit.
Relative to the sun, which is the next center of gravity. As you go up the chain you end up with the heaviest object which you cannot move relative to anything, as it is the logical point of relative movement for everything else.
Not relative to the sun, relative to momentum. Changes in the magnitude or direction of velocity are objective, not relative. These translate to real changes in momentum, from any reference frame. A real change in momentum is imparted upon the Earth roughly equal to your velocity relative to the earth multiplied by your mass at the moment your contact with the Earth ceases.
ETA: I do actually agree with your salient point above: that lifting an object is relative to a given “down”, and so it is meaningless to expect to be able to “lift” the most massive object in the universe.
You need to be thinking about n-body physics though, everything affects everything. If the earth moves, that moves the sun a little, if the sun moves, that moves the local cluster a little, etc. Why wouldn’t that affect this heaviest object?
I mean, are you suggesting that this heaviest object is simply the center of the universe and that all coordinates are defined around it? Because while that seems practical, I don’t think it’s how matter and space interact.
The universe is expanding everywhere all at once in all directions. So space itself is “moving”. It is impossible to define movement except relative to another object made from matter.
Ok, I think we’re on the same page here. But I’m still not sure about one of your previous comments, you suggested that this “heaviest object” can’t move because it would be the logical reference to which any other body is measured.
But I want to think about that a bit. Let’s say this heaviest object (HO) has something orbiting it and we’re looking at it from earth with a telescope. As the smaller body orbits, we would probably see this HO wobble, right? Meaning that even if it’s the most massive thing around, it’s still affected by other objects, it can be moved.
That is a good question. I have to think about it.
nothing is distinct from xkcd, if it exists there is an xkcd about it
No that doesn’t make sense. The thing you’re alluring at is a classical thought experiment showing contradiction in allmightiness.
P1: God is Almighty, meaning he can do anything
Therefore he must be able to create a stone he can’t lift. But then there is something he can’t do: Either he can not lift the super stone, or he can not create a super stone that he can’t lift.
Easy to resolve that conflict. A creator would by definition be outside the universe since he predated it. However, if he went into the universe, his presence there would be subject to its laws
We can easily say the creator could make an immovable object, within its environment. If the creator went into the environment, he would be subject to its laws, and the front would fall off …. Er, the object would be immovable. However when his being s beyond the environment, creating an immovable object is just part of his plan
lol I am not alluring to anything I am just giving a xkcd twist to this well known paradox
… it’s ‘alluding’, y’all
I don’t know, heavy things attract other things, so maybe it is alluring ;)
An omnipotent and omniscient being would have the ability to change words definitions or logic. They cant be stopped with a logical contradiction
The expression as I heard included “an irresistible force.”
“And irresistible is what I am, baby!”
That’s on the nsfw version of xkcd
Oglaf?
xkcd after dark, or xkcdad. But not pronounced xkd-dad.
Yeah, irresistible force is the version I know. Now I’m wondering if there are even more versions. Are they regional deviations?
They are synonyms for that usage. The immovable object is neither stopping nor resisting the force.
Well I’m from Utica and I’ve never heard the term “irresistible force”
Not in Utica, no. It’s an Albany expression.
Sure could go for some steamed hams right about now…
While not what you’re asking for, but fun fact, in Asia, this sort of paradox is represented by the story of the all-piercing spear and the unpierceable shield in Chinese philosophy. So in Chinese and Japanese, the word for ‘paradox’ or ‘contradiction’ literally means ‘spear-shield’ (矛盾).
“What happens when an unstoppable force meets an immovable object?” that image doesn’t show a force meeting an object
They met, they just didn’t interact. Kinda like me at a work party.
There is no force without interaction, just linear momentum.
“where’s the food and booze?”
That just moves the problem, what happens if I put a piece of paper between them? Unless they don’t interact with anything they still face the same problem.
I mean we have these in the universe, one example of an unstoppable force is neutrinos. These tiny particles certainly seem to contain a whole lot of energy, moving close to the speed of light. But just try to stop one.
But just try to stop one.
Fiiine. BRB, I need to build a giant underground cave.
That’s pretty simple, if there is any matter they could both interact with in the way, it would be converted to energy and either expelled to the side or shunted to another dimension.
So who would win in a fight between the Juggernaut and the Blob?
That has been debated to death before and it obviously depends on the writer and version of the characters, but in most cases neither are fully immovable or unstoppable. If they were, Juggernaut would probably just be redirected and keep going.
A little more practically speaking, Juggernaut wins easily:
-
The Blob is a mutant who can basically lock himself to the ground with a short distance around him and become immovable in relation to the ground while being able to absorb most impacts to effectively eliminate the force experience by him and thus the ground.
-
The Juggernaut is not a mutant, but an avatar of Cyttorak the Destroyer, the God/Demon ruler of the Crimson Cosmos dimension. He can tap into more and more of that power to the point where he can fight a somewhat angry Hulk on almost equal ground(he’s even defeated him with some help).
Even if you let Blob be immovable and able to ignore all kinetic force, he still has a big weakness: He’s not very superhuman when it comes to other forms of damage, or just pain in general. As demonstrated when he tried to go after one of the intelligent versions of Hulk. Hulk realized he couldn’t move or hurt him, so he grabbed his stomach and started pulling. It quickly hurt so much that he instinctively stopped anchoring himself to the ground. At which point he basically became an invincible bouncing ball since he can’t attach to the air. SoHulk treated him as one, until he sent him flying by using a big metal girder as a bat. And it’s important to note that Blob is not very strong or good at fighting when it comes to superhumans, since he basically just relies on his powers.
And to expand on the Crimson Cosmos: It is so powerful that Doctor Strange taps into it to contain Hulk. It’s even used to contain Thanos with most of the stones in the MCU(The red cloth strips that hold him is a spell called the “Crimson Bands of Cyttorak”)
-
I’m driving. I lose my brakes and can’t slow down as if my gas pedal is stuck (unstoppable force). I’m on a road that stops at a T intersection and there’s a concrete wall to keep people from going straight when they are moving vertically towards the T intersection (immovable object).
The car just goes right through the concrete wall with no damage?
Replace the concrete wall with a wooden fence. Technically the fence is immovable, but the car is going to smash right through that thing.
So is this about clarifying what exactly the objects are? I’m not smart enough for this one and am so confused…
In this example your car is not an unstoppable force, it is just a “travelling” mass
The fact that the car had brakes to begin with would suggest that it is, by design, a force which stops regularly.
The thrust of your car engine is a very stoppable force.
Concrete walls are resilient, but can be moved.
What will happen is that the kinetic energy from the collision will crumple the front part of your car, as the concrete wall applies an equal and opposite force. Ideally, the fact that some of the energy is “used” in deforming your car (and subsequently escapes as heat) decreases the amount of kinetic energy that is used to deform you.
This is soo politically charged that can’t be seen as political anymore.
My dude, it’s an arrow and a block
I don’t see the political charge. How do you mean?
(I think this is a reference to the recent “a grad student was grabbed off the street in my town last month” entry into the series and the “ooh XKCD gone political” response to same)
I have seen the current US sitiatuation be described many times as a unstoppable force (Trump) going against every law and institution, but they are characterized as unmovable, because they refuse to exert resistance to Trump advances.
Edit: a random blog using this metaphor before the election. https://yaschamounk.substack.com/p/the-danger-to-american-democracy
Given how inaccurate that metaphor is, I can say with near certainty that has nothing to do with this comic.
