Author Q&A: Cosmologist Sean Carroll on podcasting

What do CNN White House correspondent Jessica Yellin, Nobel Prize–winning physicist Kip Thorne, and professional poker player Liv Boeree have in common? All three have been guests on the weekly podcast Sean Carroll’s Mindscape.

Caltech cosmologist Carroll is the author of several well-received physics popularizations, including The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World (2012) and The Big Picture: On the Origins of Life, Meaning, and the Universe Itself (2016). In each episode of Mindscape, Carroll and a guest dive into a wide-ranging, in-depth conversation about the guest’s work and the biggest ideas emerging from it. Physics Today included Mindscape on its recent list of recommended podcasts for science lovers .

PT: What inspired you to get into podcasting?

CARROLL: A big part of it was my books. The Particle at the End of the Universe was the only book I’ve written that was not about my own work or my own ideas. I did reporting for it. I talked to people, interviewed them, got their stories. To be honest, I was not very good at it. I appeared on many people’s podcasts, but I was never really tempted to do it myself.

When I wrote The Big Picture, I had to interview people again. But it was a different kind of interview. I was talking to people just to get their ideas, not to get their stories or to have them tell me a funny anecdote that happened along the way. I talked to major philosophers, thinkers, and experts on a lot of different things, and I found that a lot of fun. I realized that maybe there was room for a podcast that was more along those lines. Once the book was done, I had no more excuse to knock on people’s doors, but now I do. I can say, “Let’s talk because I have a podcast.”

PT: How do you choose guests for each episode?

CARROLL: I want to keep Mindscape diverse in many ways. I want to have some episodes with serious thinkers and philosophers, and some that are more accessible to people who are not necessarily academically inclined. But whether I’m talking to a professor or someone from outside academia, it’s very important to get people who like to talk. There are many people who have brilliant ideas and are wonderful intellectuals but give you three-word answers to your questions. People who like to ramble on at great length are much better for podcasting purposes. It makes for a much more fun conversation.

Before I started, I made a long list off the top of my head of the kinds of people I wanted to talk to. Some of my guests are people I follow on Twitter or people whose work I’ve read. I also found out very quickly that people will volunteer themselves if they have a book out. I usually don’t take them up on that, but sometimes I do.

PT: Any upcoming guests or topics you want to tease?

CARROLL: I’ve been doing a lot of science, and I do a lot of social science, so I’m trying to bring in more humanities. I think the point of the podcast is not science or even scholarship, but ideas. And there’s some really important ideas that have to do with how we live our everyday lives: what we eat, what we drink, how we exercise. All sorts of possibilities are open to us in this format.

PT: Are there any episodes where you learned something unexpected or were surprised by the turn that the conversation took?

CARROLL: Honestly, I’ve had an extremely high batting average in terms of my enjoying the episode. I had a conversation with Joe Walston, a conservationist who works on preserving the ecosystem. Joe’s research looks at the effect urbanization is having on population growth. Once people moved into cities, they stopped having big families. The rate of worldwide population growth actually peaked in the 1960s, and there’s a reasonable expectation that 10 or 20 years from now the population of Earth won’t be growing. We may approach a new equilibrium where there are a lot more people in cities and there’s room for the rest of the animal and plant life on Earth to happily exist outside those. That’s not a reason to be sanguine. We’re still throwing off CO₂ at a tremendous rate. But it’s sort of a counterintuitive message to provide a little bit of hope.

PT: What do you hope your listeners take away from an average episode of Mindscape?

CARROLL: I think every episode should have at least one big, interesting idea. Some episodes are really just one idea, whereas others skip around a little bit. One episode is about poverty, and the next is about playing poker. But all the episodes are about smart people having intellectual conversations across boundaries. In particular, I think I have a special sort of opportunity as a scientist. We talk about disciplines interacting with each other, but it’s very rarely scientific disciplines interacting. I want to lower that barrier between physics and the rest of science.

PT: What are your favorite podcasts?

CARROLL: The only time I listen to podcasts is in the car. I have a 20- to 25-minute commute each way, so I get through less than one podcast per day if it’s an hour-long show. But I have a wide range that I listen to, from something pretty meaty like The Ezra Klein Show or Conversations with Tyler to something that’s just funny—WTF with Marc Maron is one of my absolute favorites. I generally don’t listen to science podcasts—I have enough science in my life!

PT: What’s going on in your research right now?

CARROLL: I’ve been working for a while now on the foundations of quantum mechanics and how it intersects with quantum gravity, and I’m thinking about the emergence of spacetime. I’m putting the finishing touches on a popular book about that subject, informed by my research. Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime will be published by Dutton later this year.