Proving all of math wrong

this post is a pretty good example of why mathematicians are concerned with rigor ("obsessed with pedantry" if you're feeling less generous). if you came up with this on your own then you should be proud because it's an interesting way to poke a hole in the math you've been taught.

the tools to see why this doesn't work don't come until you start learning calculus. depending on where you live this might be late in secondary school or early in college. i think the americans don't do calculus in secondary school unless they're in the "AP" and the british don't do calculus in secondary if they only do the GCSE but do do calculus in "A-Levels"? I don't know I didn't get a secondary school degree from either of these places. but I digress.

Part 1:

what you said is this:
RAogOLR.png


there's some boilerplate stuff you were probably supposed to say about x being a real number strictly greater than 0 (think about what happens if x<0 or if x = 0), but let's ignore that for a second.

basically, what's wrong is the words "infinity-eth root" and "1 ^ infinity". these don't actually mean anything, because roots and exponentiation are designed to work on numbers and infinity isn't a number.

what infinity actually is should probably be left to some very dense textbooks (you can definite it via set cardinality or via compaction or via geometry or via ...), but for our purposes it suffices to say that it is less a number and more the idea of "something bigger than all the other things".
the fact that it's an idea means you can't do math on it - for our purposes saying "infinity plus one" makes as little sense as saying "yellow plus one".

because you're doing something that doesn't make sense - doing math treating infinity as a number - you get a result that doesn't make sense.

Part 2:

but i mentioned that you can kind of approach this in a way that makes more sense using calculus.

rephrasing "infinity-eth root equals 1" using the language of calculus would look something like this:
yOLf4Cg.png


and that statement is 100% correct. noone can really have any problems with it (besides the mathematicians who don't accept the existence of infinity but let's not divert ourselves too much here).
what this statement means is something along the lines of "let's look at what happens if you take the n-th root of x, where n actually is a number. as n gets bigger and bigger, the n-th root of x gets closer and closer to 1. if you let n get arbitrarily large, the result is arbitrarily close to 1."

we can take the rigorously defined mathematical form of the root and exponentiate that to the power of infinity in an equally rigorously defined way.

Rb0Jmhb.png

when we have an x, take the n-th root as n goes to infinity, and then exponentiate it by n as n goes to infinity, we just get x back out! everything works and we have a result that matches what you might expect. using the language of calculus, when you root x and then un-root the result you arrive back at x, instead of getting some weird contradiction.

we get a nice result in this scenario, but in general, the result of the expression "1^infinity" is actually an undefined value that can be whatever you want. in the example below, the stuff in the parentheses approaches 1, but the expression as a whole is equal to euler's constant, so around 2.72!
p2nhyL8.png

this is a very nice explanation as to why taking "1^infinity" is bad, and "Limits are about the journey not the destination" is a nice quote.

Part 3:

if you really want a tricky one try this out:

hlpyDSV.png

what!? i definitely wasn't able to figure out what was wrong with this one my first time seeing it... give it a spin yourself, but if you throw in the towel (like I did) then the top two explanations in this link are both quite nice.

===========
TOO LONG DIDN'T READ SUMMARY:
infinity isn't a number and you can't use it like one or you'll be punished to an eternity of reading forum posts about basic calculus. wow react bellsprouts should be directed to the bottom right of this post.
 
this post is a pretty good example of why mathematicians are concerned with rigor ("obsessed with pedantry" if you're feeling less generous). if you came up with this on your own then you should be proud because it's an interesting way to poke a hole in the math you've been taught.

the tools to see why this doesn't work don't come until you start learning calculus. depending on where you live this might be late in secondary school or early in college. i think the americans don't do calculus in secondary school unless they're in the "AP" and the british don't do calculus in secondary if they only do the GCSE but do do calculus in "A-Levels"? I don't know I didn't get a secondary school degree from either of these places. but I digress.

Part 1:

what you said is this:
RAogOLR.png


there's some boilerplate stuff you were probably supposed to say about x being a real number strictly greater than 0 (think about what happens if x<0 or if x = 0), but let's ignore that for a second.

basically, what's wrong is the words "infinity-eth root" and "1 ^ infinity". these don't actually mean anything, because roots and exponentiation are designed to work on numbers and infinity isn't a number.

what infinity actually is should probably be left to some very dense textbooks (you can definite it via set cardinality or via compaction or via geometry or via ...), but for our purposes it suffices to say that it is less a number and more the idea of "something bigger than all the other things".
the fact that it's an idea means you can't do math on it - for our purposes saying "infinity plus one" makes as little sense as saying "yellow plus one".

because you're doing something that doesn't make sense - doing math treating infinity as a number - you get a result that doesn't make sense.

Part 2:

but i mentioned that you can kind of approach this in a way that makes more sense using calculus.

rephrasing "infinity-eth root equals 1" using the language of calculus would look something like this:
yOLf4Cg.png


and that statement is 100% correct. noone can really have any problems with it (besides the mathematicians who don't accept the existence of infinity but let's not divert ourselves too much here).
what this statement means is something along the lines of "let's look at what happens if you take the n-th root of x, where n actually is a number. as n gets bigger and bigger, the n-th root of x gets closer and closer to 1. if you let n get arbitrarily large, the result is arbitrarily close to 1."

we can take the rigorously defined mathematical form of the root and exponentiate that to the power of infinity in an equally rigorously defined way.

Rb0Jmhb.png

when we have an x, take the n-th root as n goes to infinity, and then exponentiate it by n as n goes to infinity, we just get x back out! everything works and we have a result that matches what you might expect. using the language of calculus, when you root x and then un-root the result you arrive back at x, instead of getting some weird contradiction.

we get a nice result in this scenario, but in general, the result of the expression "1^infinity" is actually an undefined value that can be whatever you want. in the example below, the stuff in the parentheses approaches 1, but the expression as a whole is equal to euler's constant, so around 2.72!
p2nhyL8.png

this is a very nice explanation as to why taking "1^infinity" is bad, and "Limits are about the journey not the destination" is a nice quote.

Part 3:

if you really want a tricky one try this out:

hlpyDSV.png

what!? i definitely wasn't able to figure out what was wrong with this one my first time seeing it... give it a spin yourself, but if you throw in the towel (like I did) then the top two explanations in this link are both quite nice.

===========
TOO LONG DIDN'T READ SUMMARY:
infinity isn't a number and you can't use it like one or you'll be punished to an eternity of reading forum posts about basic calculus. wow react bellsprouts should be directed to the bottom right of this post.
I think this is a good summary of how calculus comes into play, but I wanted to point out that this proof claims a false statement is implied by a false assumption, which still ends up saying something about the proof itself.
Let's take any number, represented by x.
The infinity-eth root of x is 1.
...
Thus, the only way this can be true is if 1 > 1.

Since 1 is not greater than 1, you have shown by contradiction that your assumption that the infinity-eth root of x being 1 for any number is not true, instead of proving all of math wrong. Here is a similar proof based on a false assumption:
Let's take x = 2.
Let x + 2 = 5.
Thus, the only way this can be true is if 2 = 3.
 
noone can really have any problems with it (besides the mathematicians who don't accept the existence of infinity but let's not divert ourselves too much here).
Wait there are actually mathematicians that don't accept the existence of infinity? That doesn't make sense to me. All you would have to do is show them the dichotomy paradox: before arriving somewhere, everything must have a halfway point. That halfway point must have a halfway point, and so on and so forth, until you reach an extremely small length like 1/4,398,046,511,104th of a foot (meter if you're a loser that uses the metric system). No matter what unit you use for the dichotomy paradox, whether it be numbers, measurement units, or even time, there's always an infinitely small number. Do they simply ignore this, or say it's undefined rather than infinity?
 
This is similar to saying 1 = 2.
Assuming a = b, we can multiply both sides by a to get a^2 = ab. Now, you can subtract b^2 from both sides to get a^2 - b^2 = ab - b^2. Factor to get (a+b)(a-b) = b(a-b). Divide both sides by (a-b), and you get (a+b) = b. Assuming a = b, then this proves that 1 = 2. (thanks to John Hush for this, that video explains why it doesn't work if you don't know)
 
Well if a mathematician doesn't "believe in infinity", they probably don't "believe" in something like a real number line, which is where the paradox comes from. I don't necessarily think the belief that infinity is something real that exists in the world must be true. Not sure if there is any proof of it though.
 
I was sitting here typing maths philosophy for like 10 minutes and then I realised that "If you put every Smogon user in a line, in a random order, there's an unimaginably massive number of possibilities" would probably be an event that would lead to mass destruction. Maybe the real question is "Is maths wrong for our society???"
 
I was sitting here typing maths philosophy for like 10 minutes and then I realised that "If you put every Smogon user in a line, in a random order, there's an unimaginably massive number of possibilities" would probably be an event that would lead to mass destruction. Maybe the real question is "Is maths wrong for our society???"
gathering every smogon user together is a bad idea for the safety of its figureheads. if i ever see dave or faint or finchinator irl it's ON SIGHT
 
Wait there are actually mathematicians that don't accept the existence of infinity? That doesn't make sense to me. All you would have to do is show them the dichotomy paradox: before arriving somewhere, everything must have a halfway point. That halfway point must have a halfway point, and so on and so forth, until you reach an extremely small length like 1/4,398,046,511,104th of a foot (meter if you're a loser that uses the metric system). No matter what unit you use for the dichotomy paradox, whether it be numbers, measurement units, or even time, there's always an infinitely small number. Do they simply ignore this, or say it's undefined rather than infinity?

when I was referring to mathematicians that don't accept infinity i was being pretty flippant (i am not a finitist and i am not even a mathematician) but I was referring to the ideas of Constructivism/Finitism/Ultrafinitism. Some practitioners are kind of cranks and their ideas are not too relevant in the grand scheme of things, but finitism is still interesting because Hilbert's work on it motivated other work like the Gödel incompleteness (see here).

In case you want a rabbit hole to go down there are some interesting discussions here and here and here and here (roughly ordered by how much I don't understand them)

These ideas are more philosophy subjects than math subjects, and I've done very little pure math and no philosophy in my life (and I'm washed), so I honestly can't tell you how exactly a real finitist would respond to your argument.
Finitism also seems to have many sneaky logic tricks that make certain things acceptable (like to some of them your recursive example would be allowable because it only uses recursion and elementary arithmetic).

I've spoilered the below bit because I want to disclaimer that this is just my interpretation. you will want to take it with a grain of salt.
However, the way I understand it (which is definitely incomplete) is:
If you want to think up an idea of infinity and do math with it and you get consistent results, then that's nice for you. But in the universe as we know it you can't really point to any ideas of infinity. You won't find something with infinite atoms and scientists can't even show that the universe is infinite. On top of this, no matter how much time they were given, a human with a pencil and paper could never calculate that infinitely small number you were talking about.
So the finitist might just reject your construction. They would say, "we could never even calculate a concrete value for your infinitely small number, so it doesn't even make sense to talk about it". If we want math that has some sort of 1:1 relation with the real world, we can work with finite numbers, even ones we get after halving many many times, but your theoretical infinitely small one can't even exist. Because it can't exist, I don't want to use it as an object within my purview of mathematics. It would make my math inconsistent with what I believe can be realized in the universe
 
1/0 = ∞
Following the same logic, that means..
1/∞ = 0

The fun fact is that 1/ ∞ is actually 0
actually no, 1/0 is not equal to infinity and neither is 1/∞ = 0 because
1/0 = ∞
would mean that
1 = ∞ x 0, which isn’t true because everything, including infinity, multipled by zero is still zero
 
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