“How to Bake Pi” — Nothing says lovin’ like mathematics from the oven
I was sitting in a neighborhood coffee shop the other day reading the last few pages of Eugenia Cheng’s new book, “How to Bake Pi: An Edible Exploration of the Mathematics of Mathematics” (Amazon link) when a man seated nearby leaned over my shoulder and asked me, “is that a book about geometry?
“Well,” I said, “it talks about geometry some, but it’s really a book about the mathematics of mathematics.”
Taking my response as something of a dodge, he reached deep into his pocket, pulled out a sheaf of lottery tickets, slapped them down on the table between us, and declared, “this is what mathematics is about. It’s about numbers.”
That popular take on mathematics pretty much sums up the first obstacle faced by those like Cheng who write about mathematics for a general audience: convincing people that math is a lot more than just computation and coming up with the “correct” answer.
Well, if mathematics isn’t about numbers, then what is it about? From the perspective of “How to Bake Pi” the question might be better phrased, “what is mathematics like?” And the answer that Cheng gives using an assortment of short recipes as a roadmap in her book is that mathematics is a lot like baking.
In this way of looking at things, mathematics is no more about numbers than baking is about, say, flour. Sure, flour appears in all sorts of recipes. When it appears, though, it can come in any a variety of forms, each with its own properties for the baker to consider. Sometimes flour isn’t used at all. And let’s not forget the other ingredients, like eggs and nuts and, a favorite of Cheng’s, chocolate.
Likewise with math, numbers when used may come in different forms: integers, rational numbers, irrational numbers, for example. But we can do mathematics with lines and curves and shapes and all sorts of other things. As our own experience with triangles in high school geometry reminds us, numbers don’t have to be the focus of mathematical investigations.
Cheng’s idea here is that there is a lot more going on with baking — and mathematics — than lists of ingredients. There are the relationship between the ingredients, how they work together, which substitutions are allowable and which are not, and what rules exist in guiding the baker — and the mathematician — in making these choices.
And ingredients by themselves are nothing more than raw materials. Bringing them to life requires a baker familiar with a repertoire of techniques and equipped an armamentarium of gadgets to wield to prepare, combine, and cook. Sometimes what you decide bake has more to do with wanting to try out the shiny, new food processor you just bought, and less with what happens to be in your pantry at the time. Sometimes it’s the reverse.
It’s a lot like that with mathematics. Sometimes mathematicians restrict their work to a particular domain of objects. They have more than enough in their pantry of mathematical ingredients to keep them plenty busy. Other times they may take a shiny, new technique and go looking to apply it to mathematical ingredients that they’ve never used before.
A second obstacle to popularizing mathematics is the perception that it is hard and that the people who do it like to keep it that way. Cheng addresses this aversion to math by explaining that mathematics is, at its core, about making hard things easy. So one of her goals becomes to humanize mathematicians and, by doing so, make mathematics itself more approachable.
To accomplish this in large measure, Cheng puts her own humanity on display: her trials with learning the high jump in high school; her pride in running the 2005 New York City Marathon; her failure to recognize a famous English soccer team while sitting in a hotel bar in London.
But first and foremost there is, of course, the delight that Cheng takes in her recipes and tales of baking for friends, not to mention her love of chocolate. The warmth that one feels reading her book is, I imagine, not unlike the warmth one would feel chatting with her in her kitchen while bathed in the wonderful smells coming from one of her desserts baking in the oven.
Why go to all the trouble to write a book to help people understand mathematics? Because, as Cheng observes, “understanding is power, and if you help someone understand something, you’re giving them power.” Read “How to Bake Pi” and you will, indeed, go away feeling empowered — and also a bit loved.
