I will just believe you did..Mountaineer wrote: ↑Sun Mar 29, 2020 10:14 amI'm more into Schrödinger's cat. Should I have posted this in the Kat thread?

## Daily "Check In" Thread For Us

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### Re: Daily "Check In" Thread For Us

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- Mountaineer
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### Re: Daily "Check In" Thread For Us

Outstanding Sheckels, just outstanding!shekels wrote: ↑Sun Mar 29, 2020 10:56 amI will just believe you did..Mountaineer wrote: ↑Sun Mar 29, 2020 10:14 amI'm more into Schrödinger's cat. Should I have posted this in the Kat thread?

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### Re: Daily "Check In" Thread For Us

The idea that the sum of all positive integers from 1 to infinity equaling -1/12 isn't just hocus pocus though. It has structure in the form of the Ramanujan Summation.technovelist wrote: ↑Sun Mar 29, 2020 9:07 am

No it isn't true. It's an excellent example of why you can't treat "infinite series" like actual things.

Again, they are abstractions, not reality.

Here's a simpler example which is equally valid:

Assume that we have two variables a and b, and that: a = b

Multiply both sides by a to get: a2 = ab

Subtract b2 from both sides to get: a2 - b2 = ab - b2

This is the tricky part: Factor the left side (using FOIL from algebra) to get (a + b)(a - b) and factor out b from the right side to get b(a - b). If you're not sure how FOIL or factoring works, don't worry—you can check that this all works by multiplying everything out to see that it matches. The end result is that our equation has become: (a + b)(a - b) = b(a - b)

Since (a - b) appears on both sides, we can cancel it to get: a + b = b

Since a = b (that's the assumption we started with), we can substitute b in for a to get: b + b = b

Combining the two terms on the left gives us: 2b = b

Since b appears on both sides, we can divide through by b to get: 2 = 1

The Ramanujan Summation has practical applications and is used in real world physics calculations, particularly in string theory.

Given that it has legitimate real world use in physics calculations such as the Casimir Effect, it's fair to say it's an actual "thing."

“My natural state is an outsider, and no matter what group I'm in or where I am, I've always felt like I'm outside the group, and I've always been analyzing the group.” - Michael Burry

### Re: Daily "Check In" Thread For Us

Oh come on Smith....Taylor series and the rabbit & turtle race analogy are both pretty cool!Smith1776 wrote: ↑Sun Mar 29, 2020 5:41 amI am 90% of my way through finishing the last math assignment I will ever have to do...for the rest of my life!

By the way, infinite sequences and series suck. Like... a lot. Did you know that the sum of all positive integers from 1 to infinity is -1/12? Okay, fine, that's actually pretty interesting. Still, they suck. A lot.

### Re: Daily "Check In" Thread For Us

It's all indeed actually very fascinating, but I'm kind of glad that any math going forward is going to be optional.

For posterity: in defense of Numberphile's video, yes it's true that in traditional maths, you can't say that the sum of all natural numbers equals -1/12. They actually explain why they pulled their slight of hand in a follow up video. They needed the video to be simple enough for general audiences. https://youtu.be/8hgeIDY7We4

It's not "true" in the traditional sense as 1 + 1 = 2, but it's a perfectly legitimate value to assign to the sum for theoretical maths and string theory.

“My natural state is an outsider, and no matter what group I'm in or where I am, I've always felt like I'm outside the group, and I've always been analyzing the group.” - Michael Burry

- technovelist
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### Re: Daily "Check In" Thread For Us

Ok, then you pay me an amount of money equal to each positive integer from 1 to infinity, and I'll pay you -1/12th of a dollar, and we'll call it square.Smith1776 wrote: ↑Sun Mar 29, 2020 4:10 pmThe idea that the sum of all positive integers from 1 to infinity equaling -1/12 isn't just hocus pocus though. It has structure in the form of the Ramanujan Summation.technovelist wrote: ↑Sun Mar 29, 2020 9:07 am

No it isn't true. It's an excellent example of why you can't treat "infinite series" like actual things.

Again, they are abstractions, not reality.

Here's a simpler example which is equally valid:

Assume that we have two variables a and b, and that: a = b

Multiply both sides by a to get: a2 = ab

Subtract b2 from both sides to get: a2 - b2 = ab - b2

This is the tricky part: Factor the left side (using FOIL from algebra) to get (a + b)(a - b) and factor out b from the right side to get b(a - b). If you're not sure how FOIL or factoring works, don't worry—you can check that this all works by multiplying everything out to see that it matches. The end result is that our equation has become: (a + b)(a - b) = b(a - b)

Since (a - b) appears on both sides, we can cancel it to get: a + b = b

Since a = b (that's the assumption we started with), we can substitute b in for a to get: b + b = b

Combining the two terms on the left gives us: 2b = b

Since b appears on both sides, we can divide through by b to get: 2 = 1

The Ramanujan Summation has practical applications and is used in real world physics calculations, particularly in string theory.

Given that it has legitimate real world use in physics calculations such as the Casimir Effect, it's fair to say it's an actual "thing."

Also note that "real world physics calculations" and "string theory" don't really belong in the same sentence without a negating qualifier...

- technovelist
- Executive Member
**Posts:**6660**Joined:**Wed Sep 15, 2010 11:20 pm

### Re: Daily "Check In" Thread For Us

A. It's "sleight of hand".Smith1776 wrote: ↑Sun Mar 29, 2020 4:45 pmIt's all indeed actually very fascinating, but I'm kind of glad that any math going forward is going to be optional.

For posterity: in defense of Numberphile's video, yes it's true that in traditional maths, you can't say that the sum of all natural numbers equals -1/12. They actually explain why they pulled their slight of hand in a follow up video. They needed the video to be simple enough for general audiences. https://youtu.be/8hgeIDY7We4

It's not "true" in the traditional sense as 1 + 1 = 2, but it's a perfectly legitimate value to assign to the sum for theoretical maths and string theory.

B. If you have to use sleight of hand, that means you are deceiving the audience.

Q. E. D.

- Mountaineer
- Executive Member
**Posts:**3920**Joined:**Tue Feb 07, 2012 10:54 am

### Re: Daily "Check In" Thread For Us

technovelist wrote: ↑Sun Mar 29, 2020 4:46 pmOk, then you pay me an amount of money equal to each positive integer from 1 to infinity, and I'll pay you -1/12th of a dollar, and we'll call it square.Smith1776 wrote: ↑Sun Mar 29, 2020 4:10 pmThe idea that the sum of all positive integers from 1 to infinity equaling -1/12 isn't just hocus pocus though. It has structure in the form of the Ramanujan Summation.technovelist wrote: ↑Sun Mar 29, 2020 9:07 am

No it isn't true. It's an excellent example of why you can't treat "infinite series" like actual things.

Again, they are abstractions, not reality.

Here's a simpler example which is equally valid:

Assume that we have two variables a and b, and that: a = b

Multiply both sides by a to get: a2 = ab

Subtract b2 from both sides to get: a2 - b2 = ab - b2

This is the tricky part: Factor the left side (using FOIL from algebra) to get (a + b)(a - b) and factor out b from the right side to get b(a - b). If you're not sure how FOIL or factoring works, don't worry—you can check that this all works by multiplying everything out to see that it matches. The end result is that our equation has become: (a + b)(a - b) = b(a - b)

Since (a - b) appears on both sides, we can cancel it to get: a + b = b

Since a = b (that's the assumption we started with), we can substitute b in for a to get: b + b = b

Combining the two terms on the left gives us: 2b = b

Since b appears on both sides, we can divide through by b to get: 2 = 1

The Ramanujan Summation has practical applications and is used in real world physics calculations, particularly in string theory.

Given that it has legitimate real world use in physics calculations such as the Casimir Effect, it's fair to say it's an actual "thing."

Also note that "real world physics calculations" and "string theory" don't really belong in the same sentence without a negating qualifier...

**Its OK if some people don’t like you, not everyone has good taste.**

### Re: Daily "Check In" Thread For Us

Haha but I can't though! Since infinity is a process and not a number. Which of course is what the whole thing relies on.technovelist wrote: ↑Sun Mar 29, 2020 4:46 pm

Ok, then you pay me an amount of money equal to each positive integer from 1 to infinity, and I'll pay you -1/12th of a dollar, and we'll call it square.

Also note that "real world physics calculations" and "string theory" don't really belong in the same sentence without a negating qualifier...

Joking aside, yes, as I posted just above, you can't assign -1/12 to the sum like 1 + 1 = 2. You're totally right in that regard. I am just pointing out it's a legitimate way to work with divergent series in a similar vein of how we work with imaginary numbers like the square root of -1.

“My natural state is an outsider, and no matter what group I'm in or where I am, I've always felt like I'm outside the group, and I've always been analyzing the group.” - Michael Burry

### Re: Daily "Check In" Thread For Us

Well, it's a stretch to say they're deceiving the audience, it's just highly theoretical and too much to have in a video for the laymen.technovelist wrote: ↑Sun Mar 29, 2020 4:48 pm

A. It's "sleight of hand".

B. If you have to use sleight of hand, that means you are deceiving the audience.

Q. E. D.

EDIT: and yes, my bad for the typo.

- technovelist
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### Re: Daily "Check In" Thread For Us

"[L]egitimate" and "divergent series" also don't belong in the same sentence without a negating qualifier.Smith1776 wrote: ↑Sun Mar 29, 2020 4:51 pmHaha but I can't though! Since infinity is a process and not a number. Which of course is what the whole thing relies on.technovelist wrote: ↑Sun Mar 29, 2020 4:46 pm

Ok, then you pay me an amount of money equal to each positive integer from 1 to infinity, and I'll pay you -1/12th of a dollar, and we'll call it square.

Also note that "real world physics calculations" and "string theory" don't really belong in the same sentence without a negating qualifier...

Joking aside, yes, as I posted just above, you can't assign -1/12 to the sum like 1 + 1 = 2. You're totally right in that regard. I am just pointing out it's a legitimate way to work with divergent series in a similar vein of how we work with imaginary numbers like the square root of -1.

But

*i*is another matter. That is easily understood as being on a number line perpendicular to the normal one, and you don't need any divergent infinite series tricks to use it.

And of course it is also key to the "most beautiful equation", so I'll give it a pass on being "imaginary".

- technovelist
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### Re: Daily "Check In" Thread For Us

Ok, but if you're claiming to explain something to laypersons, it's important to say if it is oversimplified and not really a complete and valid explanation.Smith1776 wrote: ↑Sun Mar 29, 2020 4:52 pmWell, it's a stretch to say they're deceiving the audience, it's just highly theoretical and too much to have in a video for the laymen.technovelist wrote: ↑Sun Mar 29, 2020 4:48 pm

A. It's "sleight of hand".

B. If you have to use sleight of hand, that means you are deceiving the audience.

Q. E. D.

EDIT: and yes, my bad for the typo.

I always do that in those circumstances.