Math that Moves the Needle — Quanta Magazine

My latest column for Quanta Magazine explores a century-old geometry problem that anyone who’s ever performed a three-point turn can appreciate.

Imagine you’re rolling down the street in a driverless car when you see a problem ahead. An Amazon delivery driver got their van halfway past a double-parked UPS truck before realizing they couldn’t make it through. Now they’re stuck. And so are you.

There’s a fun math problem here about how much space you need to turn your car around, and mathematicians have been working on an idealized version of it for over 100 years. It started in 1917 when the Japanese mathematician Sōichi Kakeya posed a problem that sounds a little like our traffic jam. Suppose you’ve got an infinitely thin needle of length 1. What’s the area of the smallest region in which you can turn the needle 180 degrees and return it to its original position? This is known as Kakeya’s needle problem, and mathematicians are still studying variations of it. Let’s take a look at the simple geometry that makes Kakeya’s needle problem so interesting and surprising.

You can read all about the surprising resolution of Kakeya’s needle problem in my full column for Quanta Magazine.

Sharing Instructional Materials

In a recent thread on Mastodon I was talking with Ben Leis and Tim Ricchuiti about instructional materials and I mentioned that I basically create everything I need from scratch rather than use materials that already exist. The conversation got me thinking about the challenge of creating instructional materials that can be shared.

It certainly does require a lot of work to create my own instructional materials, but it’s work I enjoy. And it really doesn’t occur to me to do it any other way. No instructional materials exist that can properly leverage the collective strengths of our classroom, so I just create materials that do.

As a result, these materials work very well for me but wouldn’t necessarily work well for others. For example, a recent lesson I wrote starts with the following question for students: “What does a b mean?” I know exactly what I want to happen as a result of that question. I have a sense of how student discourse and collaboration will unfold, and I know how the answer (and the work leading up to it) fits in the development of ideas from intuitive notions of “infinitesimally small” which arose the first day of class to the notion of “arbitrarily close” and the epsilon-delta definition of limit. And as a teacher I know how to manage the action and close the gaps when necessary.

But I doubt that same question (and the same supporting lesson materials) would work for another teacher. Of course anyone can teach this idea in this way, but the instructional design is so tailored to my context that I’m not sure how useful my materials would be to someone else.

You can see the entire thread on Mathstodon here.

Jaipur Literature Festival New York

I’m thrilled to be a part of the upcoming Jaipur Literature Festival in New York City, where I’ll be in conversation with mathematician and novelist Manil Suri. Manil’s latest book, The Big Bang of Numbers, is a tour of mathematics from the ground up, allowing the reader to the experience of the power of mathematical creation as Manil constructs the universe using only math. It is a fun, friendly, and one-of-a-kind book.

In our JLF session A Universe Built on Math, Manil and I will be talking about math, writing, teaching, and everything in between. The talk is happening on September 13th at 4:30 pm at the Asia Society. All the details can be found here.

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