Why do fractals and Pi have a special relationship?

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Discussion Overview

The discussion centers around the relationship between fractals and the mathematical constant Pi, particularly in the context of semicircles and their circumferences as they approach a limit. Participants explore concepts related to limits, paradoxes, and the properties of geometric shapes.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that the sum of the circumferences of semicircles remains at Pi as their diameters approach zero.
  • Others argue that the sum of the circumferences of two circles with diameter 1 is actually 2Pi, not Pi.
  • A participant mentions that the concept of limits is crucial to understanding the problem, suggesting that a naive approach can lead to misunderstandings.
  • Some participants reference the Koch Snowflake as a related example of limits and fractals, where the perimeter diverges while the area converges.
  • There is a discussion about the nature of the semicircles as their diameters become infinitesimally small, with some asserting they remain semicircles while others question this interpretation.
  • One participant highlights a potential paradox in the language used to describe the problem, suggesting that the phrasing may obscure the underlying mathematical concepts.
  • Another participant discusses the diagonal approximation problem, drawing parallels to the semicircle discussion and questioning the existence of a paradox in that context.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between the circumferences and diameters of the semicircles, with no consensus reached on the interpretation of the limit or the existence of a paradox.

Contextual Notes

Limitations in understanding arise from the definitions of limits and the assumptions made about the behavior of geometric shapes as they approach infinitesimal sizes. The discussion reflects varying interpretations of these concepts.

  • #31
Archosaur said:
I agree, but just because not all of his logic is flawed doesn't mean \pi = 2

My point wasn't that he's correct, my point was that your criticism was incorrect; i.e. the act of assuming the existence of pi, and then having an argument that concludes pi=2, does not in and of itself invalidate the argument; rather you have to find a flaw in the argument itself to show the conclusion is incorrect.
 
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  • #32
Office_Shredder said:
My point wasn't that he's correct, my point was that your criticism was incorrect; i.e. the act of assuming the existence of pi, and then having an argument that concludes pi=2, does not in and of itself invalidate the argument; rather you have to find a flaw in the argument itself to show the conclusion is incorrect.

I think it does invalidate the argument.

If someone were to say, "The sky is blue, so... (some questionable leaps of logic) ...therefore the sky is green.", their argument would be invalid. You couldn't have proven that the sky is purple by first stating that it is green.

He didn't just "assume the existence" of \pi,
he defined \pi as \pi/2.
He concluded that \pi = 2.

That's not a valid argument.
 
  • #33
Pi is a consistent mathematical ratio that is simply non-controversial in that respect.
 
  • #34
well, there is uniform convergence of the succession of functions of circles to the function

constant = 0 in the interval (say) [0,1] now the elements of the succession have a graph that has constant length \pi, but the limit has a graph of length 1.

Well that's not a paradox, also more complicate things can happen when you consider uniform convergence.

think of the functions defined in [0,1]

f_n(x) = \sin(1/x)/n when x \in (0,1] and

f_n(0) = 0 they all have infinite length yet they converge uniformly to the costant 0 in [0,1]
that has finite (unit) lenght.

That is no paradox: just something not very intuitive, that happen!
 

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