Why the World’s Best Mathematicians Are Hoarding Chalk

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 the top schools very frequently use it. It's a cult favorite. As soon as I used 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. 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. Slowly the math world has become aware of this, and it became a bit of a fad in some circles. 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 have 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. I got like 1,500 sticks. That's a lot of days for me. Four sticks a day. I think I'm going to 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 want to 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 ten colleagues. I would reach into my cupboard in my office and pull out another box, and we'd do the deal in my office. We all had a chalk fix, and we still do. 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. 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 giving 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.