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B1 중급 영어 17:03 Educational

Riemann Hypothesis - Numberphile

Numberphile · 5,892,859 조회수 · 추가됨 3주 전

학습 통계

B1

CEFR 레벨

5/10

난이도

자막 (268 세그먼트)

00:00

[Prof Frenkel] Can I ask you a question Brady?

00:02

[Prof Frenkel] What is the most difficult way to earn a million dollars?

00:07

[Brady] Making Youtube videos. [Prof Frenkel] *laughs*

00:11

[Prof Frenkel] Well, you probably know much more about that than I do.

00:14

[Prof Frenkel] One of the most difficult ones is to solve one of the Millenium Problems in Mathematics,

00:20

which were set by the Clay Mathematical Institute in the year 2000.

00:26

One of these problems is called "The Riemann Hypothesis".

00:30

It refers to a work of a german mathematician, Bernard Riemann,

00:35

which he did in the year 1859.

00:38

This is just one of the problems. In fact, there are seven.

00:41

And one of them has been solved so far.

00:44

And interestingly enough, the person who solved the problem has declined the one million dollars.

00:50

So...

00:51

It just shows that mathematicians work on these problems, not because they want to make some money.

00:56

I think it is now the most famous problem in mathematics.

01:00

It took the place of Fermat's Last Theorem,

01:03

which was solved by Andrew Wiles and Richard Taylor in the mid-1990s.

01:08

[Brady] But that wasn't a Millenium Problem. [Prof Frenkel] That was not a Millenium Problem.

01:11

[Prof Frenkel] The most essential thing here is what we call the Riemann Zeta function.

01:17

And the Riemann Zeta function is a function, so ...

01:20

A function is a rule which assigns to every value some other number.

01:24

And the Riemann Zeta function assigns a certain number to any value of s,

01:29

and that number is given by the following series:

01:33

1 divided by 1 to the power of s,

01:36

plus 1 divided by 2 to the power of s,

01:39

plus 1 divided by 3 to the power of s,

01:41

4 to the s, and so on.

01:43

So, for example, if we set x = 2.

01:46

Zeta(2) is going to be 1 divided by 1 squared plus

01:51

1 divided by 2 squared,

01:54

plus 1 divided by 3 squared,

01:57

plus 1 divided by 4 squared,

01:59

and so on.

02:00

So, what is this?

02:01

This is one.

02:03

This is 1 over 4.

02:04

This is 1 over 9.

02:06

1 over 16...

02:07

So this is an example of what mathematicians call a convergent series,

02:11

which means that, if you sum up the first n terms,

02:14

you will get an answer which will get closer and closer to some number.

02:19

And that number to which it approximates is called the limit.

02:24

But the limit here is actually very interesting.

02:27

And it has been a famous problem in mathematics to find that limit.

02:31

It is called the Basel problem,

02:33

named after the city of Basel in Switzerland.

02:36

And this Basel problem was solved by a great mathematician: Leonhard Euler.

02:40

And the answer is very surprising.

02:42

What Euler showed is that this sums up to pi squared over 6.

02:48

So you may be wondering.

02:50

What does this sum has to do with a circle?

02:52

Why would pi squared show up?

02:55

But Euler came up with a beautiful proof.

02:57

I'm not going to explain it now, but it's something that you can easily find online.

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