Infinitely many infinitely small numbers.

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Discussion Overview

The discussion revolves around the limit of a series involving sums of fractions, particularly focusing on the expression \(\lim_{n \rightarrow \infty} \sum^{n}_{i=1} \frac{1}{n}\) and related series. Participants explore whether these sums converge to specific values, diverge, or if they can be manipulated in certain ways. The conversation touches on concepts of limits, divergence, and the nature of infinity in mathematical expressions.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that \(\lim_{n \rightarrow \infty} \sum^{n}_{i=1} \frac{1}{n} = 1\), while others argue that the series is divergent and does not equal anything.
  • There is a suggestion that the notation used by some participants may be incorrect, particularly regarding the summation index and its role in the expression.
  • Some participants propose that if the summand does not depend on the index of summation, it simplifies to multiplying the constant by \(n\) before taking the limit.
  • Disagreement exists over whether certain limits can be taken independently of the summation process, with some emphasizing that this leads to incorrect conclusions.
  • Participants discuss the implications of treating infinity as a real number and the conceptual tools used in analysis, including infinitesimals.
  • There is a mention of the harmonic series and its divergence, with some participants suggesting that the original question may have been misinterpreted.
  • One participant questions the validity of stating that \(\lim_{n \rightarrow \infty} \sum^{n}_{i=1} 0 = 1\), indicating confusion over the treatment of limits and sums.
  • Another participant raises a question about the limit of a sum involving \(1/(n-1)\) and its behavior as \(n\) approaches infinity.
  • Some participants express uncertainty about the implications of manipulating limits and sums, particularly when the upper limit is changed to infinity.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the limits and convergence of the series discussed. Disagreements persist about the correctness of notation and the treatment of infinity in mathematical expressions.

Contextual Notes

Limitations include potential misunderstandings of notation, the dependence on definitions of convergence, and unresolved mathematical steps regarding the manipulation of limits and sums.

  • #31
HARMONIC series is divergent, but REGULARIZABLE

\sum_{n=1}^{\infty} \frac{1}{n} = - \frac{\Gamma '(1)}{\Gamma(1)}

the idea is that Harmonic series is the logarithmic derivative (a=1) of the infinite product

\prod (n+a) which can be 'regularized' to give e^{ - \zeta ' _{H} (0,a)

here the Zeta function is the Hurwitz one , the above is the definition of zeta-regularized determinat
 
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  • #32
JonF said:
No typo.

These questions stem from a thread that was around a several weeks ago, where it was stated that \frac{1}{\infty}=0. My real question that I’ve been building up to is: how can \lim_{n \rightarrow \infty}\sum^{n}_{i=1} 0 = 1
Then don't worry about it
\frac{1}{\infty}= 0
is not true in standard analysis.
 
  • #33
HallsofIvy said:
Then don't worry about it
\frac{1}{\infty}= 0
is not true in standard analysis.
This thread is 6 years old, Halls!
 

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