Book Review: How to Bake Pi by Eugenia Cheng

Title: How to Bake Pi: An Edible Exploration of the Mathematics of Mathematics

Author:Eugenia Cheng

Genre: Nonfiction, Science, Mathematics, Food and Drink, Cookbook

Publisher: Basic Books

Goodreads Summary: What is math? How exactly does it work? And what do three siblings trying to share a cake have to do with it? In How to Bake Pi, math professor Eugenia Cheng provides an accessible introduction to the logic and beauty of mathematics, powered, unexpectedly, by insights from the kitchen: we learn, for example, how the béchamel in a lasagna can be a lot like the number 5, and why making a good custard proves that math is easy but life is hard. Of course, it’s not all about cooking; we’ll also run the New York and Chicago marathons, take a closer look at St. Paul’s Cathedral, pay visits to Cinderella and Lewis Carroll, and even get to the bottom of why we think of a tomato as a vegetable. At the heart of it all is Cheng’s work on category theory, a cutting-edge “mathematics of mathematics,” that is about figuring out how math works. This is not the math of our high school classes: seen through category theory, mathematics becomes less about numbers and formulas and more about how we know, believe, and understand anything, including whether our brother took too much cake.

My Thoughts: Looking at this blog and reading the many things on it, you probably wouldn’t count me as someone who particularly loves math. In all honesty, I’m not very good at it either. But somehow from days of sitting bored and confused in Algebra class, I’ve become a voracious reader of abstract mathematical books. Why a problem is solved the way that is, how that happened historically and why is that important? These are more so the kind of questions that a historian poses to their class about the Peloponnesian war. But when you link these inquires to mathematics, it becomes infinitely more interesting.

That said, How to Bake Pi doesn’t phrase its story of math in that way. Instead, at the beginning of each chapter there is a recipe – and Cheng takes us on a brief story of what math really is. It isn’t the mindless solving of problems that high school or even university students do. Math is simply the examination of abstract ideas that are proven using logic. Throwing around words like differential equations and category theory sounds a bit frightening but underneath it all is just a desire to understand.

One of my favorite refrains of the book is that everything in math is imaginary. A straight line? Non-existent in the real world. A perfect circle? Also non-existent. In fact, when you make a mathematical proof or try to convince someone why an equation is right, you’re working off a set of assumptions. Does 12+5 always equal 17? If you’re working in the our ‘normal’ mathematical mindset, then yes. If you’re thinking of a clock that goes to 12 and then resets to 1, then it equals 5. Math is taught in school in perhaps a silly fashion, because you aren’t taught to think or understand why certain theorems exist or why the formula for a triangle works the way it does.

You’re just supposed to take everything at face value. Which… is a very strange way to learn a discipline that relies on logic rather than belief. Cheng’s book definitely challenged me in the best of ways. Math is such an incredibly rich and interesting discipline that I wish had been taught better to me when I was younger. But in lieu of that, a great abstract theory book is exactly what the doctor ordered.

Favorite Quotes:

Well, as I say to my students, feeling stupid for not having understood something before just shows that you are now cleverer than you were then.

One of the wonderful features of math is that, like with pastry, it can use quite simple ingredients to make very complicated situations. This can also make it rather offputting, like making puff pastry.

At the heart of math is the desire to understand things rather than just know them.

Rating: 5/5 Stars


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