(upbeat music)
- The legend around this chalk is that it's impossible
to write a false theorem.
- I assume the special ingredient was angel tears.
- Mathematicians from all of the top schools very
frequently use it.
- It's a cult favorite.
- As soon as I use it I was a convert.
- The chalk is one of the best kept secrets in
the math world.
- It's the Rolls Royce of chalk.
(gentle music)
(chalk scratching)
- Hagoromo is a brand of Japanese chalk.
The way it flows on a board is a bit hard to describe
in words.
- It's really hard to get.
You can only get it from Japan, you need a Japanese
person to bring it back for you.
- I discovered it when I went to visit the
University of Tokyo and one of the professors there
said to me, you know, we have better chalk
than you do in the States and I said, oh go on,
chalk is chalk.
And so I tried it out, and I was surprised to find
that he was right.
- I tried it, and I thought it was phenomenal.
It's the densest, it erases the cleanest,
it leaves the nicest line.
- If you use bad chalk often you have to press
really hard for anyone to see what you're writing
so using Hagoromo on a good board, it doesn't really
feel like you're working hard to write.
- When I'm teaching I get a feeling of energy,
confidence, and the chalk absolutely helps.
(chalk clacking)
- Slowly the math world has become aware of this,
and it became a bit of a fad in some circles.
(upbeat music)
- It was like maybe four years ago the word came out
that the company was going out of business.
I sort of jokingly referred to it as a chalk apocalypse.
So I immediately started hoarding up as much as I could.
- I ordered three boxes of Hagoromo and kept it in
my office and used it very sparingly.
- I should've bought more but I have friends that bought
boxes and boxes and boxes of the stuff.
They might very well be set for the rest of their career.
- We've got like 1,500 sticks.
That's a lot of days, four sticks a day.
I think I'm gonna make it.
- I have probably a 10-year supply still at home.
- I calculated how many boxes would I need to last for
10 or 15 years.
I didn't wanna become a chalk dealer, but I did like the
idea that I could be the first stick is free
chalk dealer on the block in my department.
- I was probably selling it regularly to maybe
eight to 10 colleagues.
I would reach into my cupboard in my office
and pull out another box and we'd do the deal
in my office.
Yeah, we all had a chalk fix.
And we still do.
(gentle music)
- The original Hagoromo chalk is slowly disappearing.
A few years ago, a Korean company bought their formulas
and did the best job of faithfully reproducing it
in Korea.
- It was mixed emotions.
I was happy to know that it would still be made.
But I was a little disappointed that I was less clever
than I thought I was.
(gentle music)
- In many ways mathematics is like craftsmanship,
in some ways it's like artistry;
in some ways it's like science.
But there's a real high craft side to getting
a beautiful lecture on a blackboard.
Mathematicians admire this in each other
and like to use the best tools for it.
- There's incredible value to this but the value
is in using it up, not hoarding it.
(gentle music)