What do your children think you do at Wellesley?

I have three kids (ages 6, 4¾, and 11 weeks). I’ve heard the elder two tell their friends, “My dad does spearmints.” The baby smiles along.

You have two main “spearmints.” How would you explain them to a layperson?

My first “spearmint” deals with dark matter, which is the vast majority of matter in the universe. Dark matter is not composed of particles that we are familiar with (protons, electrons, neutrons). It’s a fundamentally new type of particle, and it’s invisible to us. We can infer the existence of dark matter through its gravitational pull on visible objects. I’m part of a team trying to detect individual dark matter particles in the laboratory.

My second project involves making precision tests of gravity with lunar laser ranging. By timing the round trip of laser light from a telescope on Earth to reflectors on the lunar surface and back, we measure the Earth-Moon separation with a precision of one millimeter. At its heart, the experiment is nothing more than a fancy laser pointer and a fancy clock, but the results provide incisive probes of gravitational physics.

What excites you most about physics?

The prospects for discovery. In the years since my childhood, we have learned that the universe is expanding at a faster and faster rate, and that planets orbit other stars. (We know of over 1,500 confirmed extra-solar planets.) We also know that an elusive fundamental particle called the neutrino has a small but nonzero mass and morphs from one flavor to another as it travels through space. Fact, as they say, can be stranger than fiction. And I don’t believe that we’ll ever run out of mysteries!

On your faculty page, you mention using crepe batter to teach your kids algebra. Does play enhance the learning experience?

Yes! When I visit my children’s classes in preschool and kindergarten, the kids are bursting with questions. Yet by high school, that outward expression of curiosity has mostly faded. As a teacher, I think a lot about how to help students reclaim the passion they once had for exploration and discovery.

What’s the most surprising book on your nightstand?

I revisit The Bell Jar by Sylvia Plath from time to time. I once began an intro physics class with a provocative quote from that book: “The day I went into physics class it was death.”