How Does Summing Infinite Integers Equal Negative One-Twelfth?

  • Context: Graduate 
  • Thread starter Thread starter zachx
  • Start date Start date
  • Tags Tags
    infinity series
Click For Summary

Discussion Overview

The discussion revolves around the concept of summing the infinite series 1+2+3+4+... and its association with the value -1/12. Participants explore the implications of this result, its mathematical validity, and its applications, particularly in the context of divergent series and Ramanujan Summation.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants express confusion about how the sum of an infinite series can equal a negative number, questioning the implications for limits and the nature of numbers.
  • Others assert that the series is divergent, emphasizing that it does not converge to a traditional sum, but rather is associated with the value -1/12 through nonstandard summation techniques.
  • Participants mention Ramanujan Summation as a method that provides a framework for understanding divergent series, though its conceptual basis remains unclear to some.
  • There are references to the relationship between the series and the Riemann zeta function, with some participants cautioning against taking certain derivations too literally, labeling them as misleading.
  • Some contributions highlight the potential applications of these summations in physics, particularly in contexts like the Casimir effect, while others question the validity of using such results in standard mathematical practice.
  • Concerns are raised about the pedagogical implications of presenting these concepts without sufficient context, particularly regarding the use of the equals sign in relation to divergent sums.
  • Participants discuss the limitations of applying standard arithmetic properties to infinite series, noting that this can lead to erroneous conclusions.
  • There is speculation about whether the value -1/12 is unique or if similar logic could yield other results, indicating a desire for a more rigorous proof of its validity.

Areas of Agreement / Disagreement

Participants generally agree that the series 1+2+3+4+... diverges, but there is significant disagreement regarding the interpretation and implications of associating it with the value -1/12. The discussion remains unresolved on the validity and utility of such summations in mathematics and physics.

Contextual Notes

Limitations include the dependence on nonstandard summation techniques and the unresolved nature of how to interpret the results of divergent series. The discussion also highlights the challenges in reconciling traditional mathematical properties with the behavior of infinite sums.

  • #31
WWGD said:
I agree that one should encourage the challenge of ideas, but it seems like a lot of background is needed to be able to present this challenge in a coherent way; maybe if it is a really advanced class, but do you think you can use concepts like analytic continuation, at the high school level?

Maybe if you have someone particularly good at presenting the general ideas of convergence, continuation, but this is rare. Sorry if my post came off as aggressive.

But historically the formula was discovered without analytic continuation. Is it so terrible to present it analogous to the way old quantum theory is still taught before quantum mechanics? I'm pretty sure all students, even the worst, know that the "=" sign is not the usual one.
 
Physics news on Phys.org
  • #32
Here is another interesting comment on the formula and the place of "formal derivations" by Atiyah in his essay "How Research is Carried Out" (https://books.google.com/books?id=YJ0cZwxLECAC&printsec=frontcover#v=onepage&q&f=false, p213)

"The next point I want to mention is the distinction between formalism and rigour. Again this is a dichotomy in mathematics which has a long history. In the formal kind of mathematics you do things without worrying too much about precisely what they mean as long as they give the right answer. You might say this only happens in applied mathematics but that is not quite correct; I think that it also occurs in pure mathematics. Of course, historically, there are famous examples of the formal approach. The most famous practitioner, no doubt, was Euler, who, as you know, produced many magnificent formulae. He "evaluated" such wildly divergent series like ##\sum_{n=1}^{\infty} n = -1/12##. It was only a century or so later that precise meaning could be attached to such formulae."
 
  • #33
At about 1:11:20 ish he starts talking about 1+2+3+...

I found this quite helpful
 
  • Like
Likes   Reactions: cuallito and atyy

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 17 ·
Replies
17
Views
5K
  • · Replies 6 ·
Replies
6
Views
3K