The video owner has disabled playback on external websites.

This video is no longer available on YouTube.

This video cannot be played right now.

Watch on YouTube

AI学習ツールを解放

登録して、すべての動画からより速く学べる強力なツールにアクセスしましょう。

シーン解説 フレーズハンター カードで復習 シャドーイング練習 トークバック
無料で登録
B1 中級 英語 7:50 Educational

ASTOUNDING: 1 + 2 + 3 + 4 + 5 + ... = -1/12

Numberphile · 9,684,438 回視聴 · 追加日 3週間前

学習統計

B1

CEFRレベル

5/10

難易度

字幕 (136 セグメント)

00:00

I'm gonna give you an astounding result

00:02

Astounding?

00:03

An astounding result

00:04

So I'm just gonna write down a little sum

00:06

I'm just gonna see what answer it gives.

00:08

1 + 2 + 3 + 4 + duh duh duh duh duh

00:13

And I include all the natural numbers, so all the way up to infinity

00:18

So what do you reckon the answer to this is, Brady?

00:21

-Well I would say it would go to tend towards infinity.

00:25

Yeah, that makes sense, doesn't it.

00:26

The answer to this sum is -- remarkably -- minus a twelfth.

00:32

It's amazing! I mean, I first saw this result when I start learning a bit of String Theory

00:37

And what's even more bizarre is that this result is used in many areas of physics

00:44

This is a very well known string theory textbook by Joe Polchinski. As you can see,

00:48

sort of quite early on, page 22, we have this statement here which is that the sum of

00:53

all this is --- basically saying the sum of all the integers ---

00:56

all natural numbers all the way up to infinity, is, minus a twelfth.

01:00

Alright so we're going to prove now,

01:02

Without getting our knickers in a twist with Riemann zeta functions, we gonna prove

01:06

in quite simple way, why the sum of all the natural numbers is indeed minus a twelfth.

01:12

So, to do that we're gonna do this in a number of steps.

01:15

We're gonna to look at a few different sums.

01:16

The first sum that I want to look at, I'm gonna call it S1.

01:20

And it's 1 -1 +1 -1 +1 -1 and so on.

01:28

That's the first sum I wanna look at in principle.

01:30

The second sum I'm gonna look at is 1-2+3-4 and so on

01:39

Carry on in that process all the way up.

01:41

And the third one is of course going to be

完全な字幕は動画プレーヤーで利用可能

練習問題に挑戦

この動画から語彙・文法・読解の練習問題を作成

語彙と文法 読解クイズ IELTS試験 ライティング練習
登録して練習
まだコメントがありません。最初に考えをシェアしましょう!

登録してすべての機能を解放しよう

進捗を追跡、単語を保存、演習で練習しよう

無料で語学を始める