Watercolor illustration of figs.

(iStock.com/Angelina Melik-Akopian)

Science fare

Physicist David McCowan, SM’08, PhD’14, explains food science to lay readers in the Takeout.

As a student, David McCowan, SM’08, PhD’14, studied theoretical condensed matter, focusing on the liquid-to-glass transition. As a UChicago laboratory instructor, he teaches physics majors to develop science intuition, to punch holes in everything they learn. And as a food-science columnist for the Takeout—part of the Gizmodo Media Group—he explains why you shouldn’t put a fork in the microwave. (Hint: it’s more about the shape than the metal.)

This interview has been edited and condensed.

How did you start writing about food science?

I had been following food and pop culture journalist Kevin Pang, who used to work at the Chicago Tribune and wrote for magazines like [now-defunct] Lucky Peach. When he joined the A.V. Club in 2016, Kevin put out a call for writers who were not food journalists. He wanted different voices for his new venture the Takeout, so I threw my hat in the ring. I’d already written about food, though not from a science angle; I’d mostly written about people or restaurants or spirits for Chicago Foodies. He loved that I’m a physicist, so I started writing the Food Science column in late 2016 and publish a new article every month or two.

How do you decide what to dig into?

As soon as anyone finds out you’re writing about food science, they have ideas for you. I get questions from Kevin, my wife, random people. Not all are in the realm of physics. A lot of my column is about chemistry, biology, and even engineering. Being one step removed from the subject matter is sometimes helpful because I know exactly when I’ve learned enough to understand it. With physics I’ve always got the exceptions in my head and have to hold back.

I’ve written about whether it’s safe to eat deli meat with that metallic sheen [it is], how to saber a Champagne bottle, and the difference between butter and margarine.

How do you research these stories?

For physics stories, I’ll figure out as much as I can on my own. For other science, I’ll turn to journal articles occasionally but usually I talk to people. For the margarine story I spoke with Elaine Khosrova, author of Butter: A Rich History, who was a great font of knowledge, and from there I could approach the margarine angle.

Stories like how to revive soggy French fries are fun because you can experiment. So a combination of seeing what experts think and trying out what I can at home. But articles like the metal-in-the-microwave one, that’s more theoretical.

You wouldn’t actually stick a fork in the microwave.

No. But that was a good story for me because it’s all about electrodynamics. Your microwave is setting up electric fields in the metal, and the fields get very strong at points. A curved metal sculpture should distribute the electric fields fine. Metal racks that come with microwaves—all smooth curved rods. You won’t have any electric arcing.

But a fork or crumpled foil—they have points and edges where electrons can bunch up, and when there are too many electrons in one place, they want to jump through the air to find a better spot. That’s bad news.

Even though I advise on what in principle is microwave safe, like a perfectly smooth metal bowl, I don’t know if your bowl has a micropit that would blow up your microwave. There’s always a big asterisk.

What’s your favorite story so far? 

How to Play God with Fruit: A Guide to Ripening,” because it touches on how weird the plant kingdom is. My favorite part of the research was about figs. We think of them as fruit, but they’re more like an inside-out flower, and they get pollinated by wasps. The crazy part, though, is that these two creatures are completely dependent on each other for survival.

The wasps need a place where their offspring can grow up safe, so females will burrow into male figs—the kind we don’t eat—and lay eggs inside. The mother dies in there, but when her babies are born, they mate, the female wasps collect fig pollen, and the wingless males chew an exit path out of the fig. Their job done, the males die while the females escape and look for their own figs to crawl into. Sometimes they mistakenly pick a female fig—the kind we do eat—where the flower’s structure prevents her from laying eggs. She successfully pollinates the fig before she dies, and the fig ripens into the fruit we love. So every fig you eat has at least one dead wasp in it.* 

In ancient Egypt, the fig tree species and associated wasp got geographically separated. So the trees would bear fruit, but they never got pollinated and would never ripen. Someone figured out that if you cut the fruit open, it would eventually ripen, but no one knew why. 

Today we know the answer. If you score a fig, it goes into defense mode and releases the stress hormone ethylene, which also is the hormone responsible for ripening. So the cut figs are screaming in death and telling all their fig friends that they’re about to die too, and then they all ripen together.

These types of stories are great because you find fascinating research and can also offer practical advice. You have a banana that’s not ready to eat—this is what you do.

Do your writing and teaching ever cross paths?

I write a lot of science every day, working on lab manuals and helping students with their formal scientific writing. I try to convince them how similar science writing should be to work in other classes. Scientific writing is hard to read—passive voice, clinical, dispassionate—because of archaic conventions that don’t serve the reader. You can’t be completely conversational in journal articles, but there’s no downside to writing more accessibly.

I tell my students that the paper they write on Dante’s Divine Comedy has a lot more in common with lab reports than they realize. They’re presenting a thesis, arguing it, and providing support. Sometimes the students’ takeaway is that labs are like taking a journey through Inferno, but that’s not quite my point. 

*Fellow fig lovers: An enzyme digests the wasp. So those crunchy things? Seeds.