Is 0/0 the Key to Understanding Infinity?

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The discussion centers on the mathematical expression 0/0, which is classified as "indeterminate" rather than "undefined." Participants clarify that while both numerator and denominator can approach zero, the lack of a unique value for 0/0 means it cannot be assigned a definitive numerical result. The conversation emphasizes the importance of understanding limits in calculus, particularly in the context of functions approaching zero, and the distinction between indeterminate forms and undefined expressions.

PREREQUISITES
  • Understanding of limits in calculus, specifically the concept of indeterminate forms.
  • Familiarity with mathematical notation and operations, particularly division.
  • Basic knowledge of functions and their behavior near critical points.
  • Awareness of the distinction between "undefined" and "indeterminate" in mathematical contexts.
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  • Study the concept of limits in calculus, focusing on indeterminate forms like 0/0.
  • Learn about L'Hôpital's Rule for evaluating limits involving indeterminate forms.
  • Explore the definition and properties of derivatives, particularly in relation to limits.
  • Investigate the implications of indeterminate forms in real-world applications and mathematical modeling.
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Mathematics students, educators, and anyone interested in advanced calculus concepts, particularly those dealing with limits and indeterminate forms.

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If both numbers approach 0 but one does not know their exact state, doesn't that mean the result can be either 1 or anything around it up to -∞and +∞? Does that in turn mean that 0/0 = Everything?
 
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cdux said:
If both numbers approach 0 but one does not know their exact state, doesn't that mean the result can be either 1 or anything around it up to -∞ and +∞? Does that in turn mean that 0/0 = Everything?

It means it's undefined when written simply as ##\displaystyle \frac{0}{0}##. "Undefined" means we do not assign any value to it.

In analysis, limits of the form ##\displaystyle \lim_{x \to a} \frac{f(x)}{g(x)}## where ##\displaystyle f(a) = g(a) = 0## may be 0, ∞, -∞, any real number at all, or undefined. It simply depends on the exact definition of the functions.
 
My full reasoning:

"0/0" via a/b: a, b tend to 0

1. The two numbers are independent hence they can be approaching zero but no one knows if they are the same or not

2. That means their result can be either 1 or anything around it.

3. i.e. it can be between -oo and +oo

i.e. 0/0 = Anything.

hence 0/0 is buzzing around 1.
 
It means that 0/0 is undefined. You can write the symbols on a piece of paper, but they don't mean anything.
 
I could further describe it as a cloud of numbers around 1. I wonder if it has Quantum Mechanical implications.
 
Another term that is often used to describe \frac{0}{0} is indeterminate.
 
cdux said:
I could further describe it as a cloud of numbers around 1. I wonder if it has Quantum Mechanical implications.

No, not even slightly. This stuff you hear about how quantum mechanics replaces the notion of a point particle with a "cloud"... it's a very hand-wavey oversimplification of stuff that actually has a very precise mathematical description using precise mathematical concepts with no inherent fuzziness.

The problem with trying to find a meaning for ##0/0## is that it doesn't have any meaning to find. Sure, you can write it down on a piece of paper, but not everything written down on paper has to have a meaning. When you write ##0/0##, you're basically saying "Hey - ##0## is a mathematical symbol; ##/## is a mathematical symbol; let's put them side by side and ask what it means". You could just as well ask what the value of ##)+4## should be - I got that the same way, by combining mathematical symbols in a way that makes no sense. The only difference is that it's more obvious that ##)+4## can't be expected to mean anything; ##0/0## wants to trick you into thinking that it might mean something.

Go back and reread Curious3141's post above - he's pointing out the right way of proceeding when you find yourself thinking that you're looking at a ##0/0## situation. Also, if your math is up to it (somewhere around the second or third year of high-school algebra is enough background to give this a try) you might want to look at the mathematical concept of the "derivative of a function"- this is one of the most important and practically useful applications of these techniques.
 
Last edited:
cdux said:
If both numbers approach 0 but one does not know their exact state, doesn't that mean the result can be either 1 or anything around it up to -∞and +∞? Does that in turn mean that 0/0 = Everything?
What was your purpose in posting this? You ask a question but then ignore all responses. Your "mystical" ideas on what 0/0 means have nothing to do with mathematics.
 
cdux said:
If both numbers approach 0 but one does not know their exact state, doesn't that mean the result can be either 1 or anything around it up to -∞and +∞? Does that in turn mean that 0/0 = Everything?
We can't define it uniquely. Any number ##x## satisfies ##0x=0##, so there isn't a unique value to give for ##\frac{0}{0}##. It has nothing to do with a "cloud" or "buzzing." It's indeterminate.
 
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  • #10
Mandelbroth said:
We can't define it. Any number ##x## satisfies ##0x=0##, so there isn't a unique value to give for ##\frac{0}{0}##. Thus, it's undefined. It has nothing to do with a "cloud" or "buzzing." It's undefined.
Better: It's indeterminate, not undefined.

Compare ##0x=1## with your ##0x=0##. Every number ##x## satisfies the latter expression, but none satisfies the former. Thus ##\frac 1 0## is undefined but ##\frac 0 0## is intedeterminate.
 
  • #11
D H said:
Better: It's indeterminate, not undefined.

Compare ##0x=1## with your ##0x=0##. Every number ##x## satisfies the latter expression, but none satisfies the former. Thus ##\frac 1 0## is undefined but ##\frac 0 0## is indeterminate.
Yes. Pardon me. I meant to say indeterminate.
 
  • #12
cdux said:
If both numbers approach 0 but one does not know their exact state, doesn't that mean the result can be either 1 or anything around it up to -∞and +∞? Does that in turn mean that 0/0 = Everything?

In another thread you say that you try to give a physical meaning to mathematical ideas. This is an incorrect approach to mathematics and your thinking about 0/0 illustrates this. You are assuming the symbols 0/0 mean something "real" and you are attempting to investigate this supposedly real phenomena by thinking about some process. This is what can be called a "Platonic" approach to math. You think that mathematical things have some existence before we bother to say precisely what those things are.

Many people have such feeling about triangles, the integers, the real numbers, finite groups etc. Where Platonic reality stops and the feeling that mathematical things are "just definitions" varies from person to person. However, from a point of view of learning math, you'll get completely screwed up if you substitute your own private ideas about what mathematical things are for their formal definitions - or lack thereof. People who do this build up their own fantasy worlds that never quite agree with mathematics.
 
  • #13
Who told you it's not wrong? Next time try to answer with no insults.

Just because someone postulates something it doesn't mean he has a Messiah complex and you have to attack him.
 
  • #14
I see no insults here. Please report anything you see as an insult and do not respond in the thread about them. Let's keep this on topic.

Also, cdux, you seem ot have your mind already made up. Did you ask this because you didn't know the answer but wanted input from other people? Or did you make this to advance your own theory?
 
  • #15
micromass said:
I see no insults here. Please report anything you see as an insult and do not respond in the thread about them. Let's keep this on topic.

Also, cdux, you seem ot have your mind already made up. Did you ask this because you didn't know the answer but wanted input from other people? Or did you make this to advance your own theory?

For the second time, I have no Messiah complexes. An idea can be expressed explicitly, do I really have to add tons of text apologizing "It may be wrong guys, help me", to avoid being treated like having Narcissist Personality Disorder?
 
  • #16
cdux said:
For the second time, I have no Messiah complexes. An idea can be expressed explicitly, do I really have to add tons of text apologizing "It may be wrong guys, help me", to avoid being treated like having Narcissist Personality Disorder?

Nobody said this about you, except you.

So, of the answers you were given, do you think they were helpful? Any more concerns about them?
 
  • #17
They are helpful, though to be honest it's mainly on being rigorous, which is helpful of course.

It's still sane to say that 0 x Anything = 0 in those conditions so 0 / 0 = Anything pans out.

But excuse me while I don't look very closely to responses that are basically sarcastic.
 
  • #18
cdux said:
They are helpful, though to be honest it's mainly on being rigorous, which is helpful of course.

It's still sane to say that 0 x Anything = 0 in those conditions so 0 / 0 = Anything pans out.

But excuse me while I don't look very closely to responses that are basically sarcastic.

I really see no sarcastic responses here, but never mind.

Anyway, your point of view is that you see division as a multi-valued function. This is a perfectly ok point of view. And math can be developed that way and it gives us a very elegant theory. But you should realize that this is not the convention that mathematics takes. It could take that convention, no problem with it. But it doesn't.

So while there is no problem doing things the way you do. You should keep in mind that all other people do it differently.
 
  • #19
I know, I really should be more rigorous concerning mathematics.

I have this bad habit of overanalysing it and doing little math.

I guess I'll have to google 'mathematical rigor'..
 
  • #20
cdux said:
They are helpful, though to be honest it's mainly on being rigorous, which is helpful of course.

It's still sane to say that 0 x Anything = 0 in those conditions so 0 / 0 = Anything pans out.
No, your latter equation does NOT pan out. Division by zero is not defined, so you can't get from 0*x = 0 to 0/0 = x.
 
  • #21
Mark44 said:
you can't get from 0*x = 0 to 0/0 = x.

I didn't. The reasoning was different.
 
  • #22
cdux said:
It's still sane to say that 0 x Anything = 0 in those conditions so 0 / 0 = Anything pans out.

Mark44 said:
No, your latter equation does NOT pan out. Division by zero is not defined, so you can't get from 0*x = 0 to 0/0 = x.

cdux said:
I didn't. The reasoning was different.

I have to say I'm having some trouble understanding your position here. If you're using the ##/## symbol as the division operator, then I don't understand how you can say that an expression containing ##/0## does not involve division by zero. Nor do I know of a way to get from ##Ax=B## to ##x=B/A## that doesn't assume that division by ##A## is a valid operation.

But this is all a bit beside the point... Curious3141 pointed you in the right direction way back in post #2 and I tried another constructive response in the last paragraph of post #7 of this thread. Have you followed up on these? It's really hard to improve on the current machinery for handling ##0/0## problems if you don't know what that machinery is and what it already does.
 
  • #23
Mark44 said:
you can't get from 0*x = 0 to 0/0 = x.

cdux said:
I didn't. The reasoning was different.

This is what you said:
cdux said:
It's still sane to say that 0 x Anything = 0 in those conditions so 0 / 0 = Anything pans out.

I paraphrased what you wrote (Anything --> x). It doesn't matter what your reasoning is. You started with 0x = 0 and concluded that 0/0 = x, so you apparently divided both sides of the first equation by zero. This is not valid to do.
 
  • #24
Mark44 said:
This is what you said:


I paraphrased what you wrote (Anything --> x). It doesn't matter what your reasoning is. You started with 0x = 0 and concluded that 0/0 = x, so you apparently divided both sides of the first equation by zero. This is not valid to do.

Jesus, read the 2nd reply of the thread. Or even the OP.
 
  • #25
I think the thread would benefit from clearly addressing the question of whether "0/0" has a definition or not. This depends on the context for using the symbols "0/0".

Some books may take the trouble to define "indeterminate forms" of limits and "0/0" is one of these.

However, there is no definition for "0/0" as a number. Trying to "prove" that "0/0" is NOT a number or that it is an "indeterminate" number (whatever that may be) by using a series of mathematical arguments is doomed to failure since you must begin by invoking the properties of something that has no definition.

If we interpret "a/b" as notation for an algorithm that says "To compute a/b = c find the unique number c such that a = bc and we interpret "0/0" as an abbreviation for setting a = 0 and b = 0 in that algorithm, then we can rationally discuss whether that algorithm can product a unique output.
 
  • #26
Stephen Tashi said:
If we interpret "a/b" as notation for an algorithm that says "To compute a/b = c find the unique number c such that a = bc and we interpret "0/0" as an abbreviation for setting a = 0 and b = 0 in that algorithm, then we can rationally discuss whether that algorithm can product a unique output.

Is it not possible to produce a fuzzy output? My understanding is that a/b with them independently approaching zero, will produce a fuzzy 'anything' number around 1. PS. If they are equal it will produce 1.
 
  • #27
A weird postulation this may produce is that if that 'anything' has a tendency to be closer to 1 rather that infinities then it might point towards why physical numbers tend to not be infinite.
 
  • #28
Isn't this thread slightly redundant? That was the oppinion when I began reading...now I have a headache with all the talk about algos, anythings, psychological complexes and what-nots..…
 
  • #29
cdux said:
Is it not possible to produce a fuzzy output? My understanding is that a/b with them independently approaching zero, will produce a fuzzy 'anything' number around 1. PS. If they are equal it will produce 1.

That process does not produce a fuzzy output, it produces an exact result. What that result will be depends on exactly how ##a## and ##b## approach zero - this is the point that curious3141 made way back in post #2 where he describes how to assign a value to ##a/b## when ##a## and ##b## are independently approaching zero.
(BTW, the value need not be especially near one; depending on how ##a## and ##b## approach zero, we can get anything between ##-∞## and ##+∞##.)
 
  • #30
Nugatory said:
That process does not produce a fuzzy output, it produces an exact result. What that result will be depends on exactly how ##a## and ##b## approach zero - this is the point that curious3141 made way back in post #2 where he describes how to assign a value to ##a/b## when ##a## and ##b## are independently approaching zero.
(BTW, the value need not be especially near one; depending on how ##a## and ##b## approach zero, we can get anything between ##-∞## and ##+∞##.)

Both approach towards zero so they will both tend to be two very small numbers. This points to a similarity. They are not arbitrary, they are specifically very small. Hence it comes to reason that while the result can be anything between -∞ and +∞, they will have a bias towards 1 rather than ∞.

The same would be true for ∞/∞.
 

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