David Spergel '82

"Find things in which you have an unfair advantage." 

David N. Spergel is the Charles Young Professor of Astronomy on the Class of 1897 Foundation and Chair of the Department of Astrophysical Sciences at Princeton University. He also is Associate Faculty in both the Department of Physics and the Department of Mechanical and Aerospace Engineering at Princeton. Spergel was a member of the WMAP science team and the lead author of the most cited paper in physics in the new Millennium which described the cosmology based on its results. Spergel is a MacArthur Fellow, a Fellow of the APS, and a member of both the National Academy of Sciences and the American Academy of Arts and Sciences. Spergel shared the Gruber Prize and the Shaw Prize for his work on cosmology. He currently chairs the NAS Space Study Board and co-chairs the NASA Science Working Group for the WFIRST mission. Time Magazine listed Spergel in its 2001 issue as one of America's top scientists and in its 2012 issue as one of the 25 most influential people in Space.

Read and watch to learn how David spends his days as an astrophysicist, mentor, and political adviser, how his greatest scientific discovery began with a failure, and why you should find an area in which you have an unfair advantage.  

1. Tell me about your path since graduation.

I followed a very straight path. When I came to Princeton as a freshman, I thought physics was really exciting. My junior year I worked with a visiting professor from Oxford. I wrote to him my senior year to follow my girlfriend at the time, who was going to Oxford as a Rhodes Scholar. I spent a year at Oxford (we had broken up long before we got there). Then I went on to Harvard and got my Ph.D there, and after getting my Ph.D I returned to Princeton, first to the Institute for Advanced Study as a postdoc, and then I joined the faculty here at Princeton. I felt as a freshman I wanted to be a professor at Princeton, and I’m now a professor at Princeton.

2. Is there anything you wish you had known when you were graduating?
I can't think of a single phrase that stands out that, had someone told it to me, I would have known enough to listen and done something differently. There's no right path for people, in that sometimes you know what want to do at seventeen, and there are some people who figure out what they want to do at forty. And a lot of people I know have reinvented themselves successfully. People don't need to feel that they need to know what they’re doing.

3. What advice would you give to a recent graduate?
I’d encourage people to explore, to be open to new experiences, and to find something they love. What you will do is spend most of your day at work. Looking at my friends, my peers, there are people who have jobs, and people who have careers and passions. Find something where you have a career and passion.

4. How do you spend your days?
What I end up spending my day with varies. I teach. Right now I'm teaching the big Introductory Astronomy Class, so I'm going in front of a lot of people and speaking; a lot of mentorship, a lot of working one-on-one with people from undergraduates to graduate students to postdocs. Now many of my former students are faculty members and I'll end up talking to them about their career. Mentoring people and working with them on projects, and developing them as scientists is a big part of what I do. At this point, also, I do a lot of things that might be really called “political”. I am Chair of what's called the Space Studies Board and the National Academy of Sciences. The National Academy was set up by Abraham Lincoln to advise the federal government on science policy. In April, I was in Washington for nine days, and talked to people on the the Hill, the House Science Staff, the Senate Science Staff, talked to folks at OMB and OSTP at the White House. I spent a number of days at NASA headquarters talking to people there, and also served on the NASA Advisory Council. One of the other things that I do with NASA is I run the science definition team for a big project. This is a project that’s really the successor to the Hubble Space Telescope in many ways. NASA was given a gift from the National Reconnaissance Organization of two telescopes that had not been launched. I've been working on how we can use these telescopes to study everything from extrasolar planets to the basic properties of the universe in terms of fielding questions on cosmology. That work involves working with a team of really excellent people throughout the country: my co-chair at NASA and about 30 scientists at NASA and universities. And more broadly interesting, involving the whole astronomy communities, running conferences with a couple hundred people, writing reports, engaging people, building the political support and the scientific interest in the astronomy community to enable this mission. And this will be a two billion dollar mission, so this is a big project. Making things of this scale happen requires drawing together a consensus, bringing together a lot of people to work towards a common goal. So it's an interesting combination of scientific vision and political consensus-building skills. This is not something that was part of my physics classes. I've learned somewhat over the years about doing things like being a department chair, but in many ways I felt that Princeton prepared me for it in the other classes I took and the other activities I was involved with outside of my core courses.

5. What is the career advice you give to the many people you mentor? 

Now what I always tell my students and graduate students and postdocs, is to find things in which you have an unfair advantage. This was something that John Bahcall, who was my mentor at the Institute for Advanced Study, said. Always choose problems as a scientist where you can bring to that problem something new, and that often means coming in with an idea from a new area. Just because data improves with time, there are things that we can do now that people couldn't do 20 years ago, so that becomes your unfair advantage over people in the past. Sometimes your unfair advantage is a novel perspective on something. I think people who can find an area in which they have an unfair advantage end up going further.

6. Have you taken any major risks in your career?
I think I have sometimes been too risk-averse, you know. I think I have probably missed some opportunities, perhaps intellectually and professionally, by not taking risks. Some of that is that I've been pretty comfortable where I am, happy where I am, so you don't want to take those chances. There are times when I've taken risks and they failed, and that's been ok. They've worked out well anyway. Some of the risks that I’ve taken accidentally worked, or certainly choosing to work on the problems sometimes blossomed into new things… but there are also choices I’ve made where I've worked on the field for a year or two, tried to develop some theoretical ideas, and it didn’t work out. So I think it's important to take risks, but it’s also important to know when to stop. When you play poker, it’s important to know when you need to leave the table; when you're working on a scientific problem, I think it's a good approach. If at first you don't succeed, try, try again… but after three tries, move on to something else.

7. Tell me about a time you failed.
I'd say the biggest failure that I had professionally was that I spent a lot of time working on the idea that the formation of galaxies, the original structure, was driven by something called Cosmic Texture. What’s that? We think the early universe has gone through a series of phase transitions, a lot like water forming ice. You put water in your freezer and form ice cubes, you'll notice the little air bubbles in the ice cubes—those are defects in crystals because the ice froze so quickly. Something very similar to that could have happened to the universe, and the idea that I worked on was that those little bubbles in the ice would lead to the formation of galaxies. It was an elegant idea, I spent a number of years on it, I worked with a bunch of students on this, and it does not describe the way the universe works. Had I known that in the beginning, I shouldn’t have worked on it, but you don't know that, and along the way you learn new tools to learn,new ways of thinking about things.

8. How did that failure give you new ways of thinking about things?

Back in 1992, during the COBE experiment, which was NASA's first experiment to map the microwave background and measure the amplitude of fluctuations, I was at the American Astronomical Society meeting where the results were announced and I was being interviewed by TIME magazine by Mike Lemonick. I saw the results and I said, “We're dead,” and I knew that several years of work were in the wrong direction. My first reaction was to be a bit depressed about it. I went back to Princeton and started thinking about what the results meant, and I realized that there were actually no conferences taking place right after this announcement. There are often so many meetings going on, but no one knew NASA was coming, so there wasn't a meeting planned. So on relatively short notice, I organized a workshop here Princeton. I had about 60, 70 people here on three weeks notice, and we had an excellent meeting. At that meeting, one of the things that happened was that some of my colleagues got up and said that these observations showed that the geometry of the universe was flat, and I felt that that claim just wasn't right, so I decided to work out what the predictions would be for different geometries, and we wrote a paper. Soon after that, a group of scientists led by Chuck Bennett at Goddard Space Flight Center decided to put together a proposal for a new mission. This was a group of experimentalists, and they wanted a theorist to be on the proposal. Looking at my then-recent paper on the geometry of the universe, they thought that it would be useful to have me involved. I then started thinking about the implications of microwave background measurements, realized we could measure the age and shape and basic properties of the universe, which we proposed to NASA to build the mission. I then spent the next 15 maybe 17 years of my life working with this project. It’s ended up becoming the most important thing that I did. We determined the basic properties of the universe, and showed it was 13.7 billion years old. And when I look over the trajectory, this really started with a failure. It started with things not working out, ideas not going the right direction, but by just sticking with it and going off and asking “Where can we go next?”, it took me on a path that ended up leading to some really exciting science.

9. What are your favorite things to do outside of work?
I run every day. After I came down with thyroid cancer - I was treated for thyroid cancer four years ago and had a couple of surgeries - and after that I decided that I'm going to get myself in shape. One advantage of thyroid cancer is you get put on Synthroid. Thyroid controls your energy level, and they tune you a little hot. It’s kind of like revving an engine. As a result, I need about an hour less sleep than I used to. So I started running and I've run half marathons every year, and am now training for a triathlon. At least that’s become one of my hobbies now. And this is a good argument for a big annual checkup. In my annual checkup, my physician noticed a bump examining my thyroid, and said I needed to go for tests, and I went for tests, and the bump was something serious. So it just showed up in a general exam.

10. What other advice do you give to people you mentor?

One of the things I encourage people to do is to ask people for advice. Most people think that what they’re doing is interesting, and they're happy to tell you about it. Reach out to people. I think one of the advantages of Princeton is it’s small; it’s a good student to faculty ratio. Faculty members are generally very eager to talk to students, though it's always good to email in advance and ask, “When is a good time?” The email that you send to someone that says, “I'd like to have half an hour to talk, when would be a good time?” almost always gets an answer, ‘Yes.” Knock on the door, “Are you busy now?” the answer is also usually "Yes".

11. What else do you like about your job?
One of the reasons I like being at Princeton is that I like working with smart people, and being at Princeton really spoils you. Students are really bright, the faculty are really bright, the caliber of people you interact with intellectually is very high. It is not representative of the real world.

12. If time and money weren’t factors what would you do with your life?
Money doesn't drive my choices at this point. My view on salary is that not having money makes you miserable. Once you have more than enough to live comfortably, it doesn't matter so much. I’m much  more limited by time. You know, if there were more hours in the day I’d do more. There are just lots of different things I’d want to do. One of the things that I find a bit scary at 54 is you realize maybe you have 16 to 20 years left professionally, and you start thinking about “What are the choices I want to make? What's the most impactful thing that I could do with my time in the next decade or so? How can I best make use of my skills?”

13. It sounds as if you already were thinking about life in that way.

At this point, you know, my life expectancy is probably into the mid-eighties…but any day something weird can happen. It was a very interesting experience in some ways, having cancer and going in the second time for surgery and thinking about “What would happen if I die?” It's something that I wouldn’t recommend spending all your time on, but I think it's something that's valuable to do occasionally— to think about what you’ve accomplished, how you’d be missed. Things like, I realized my older two kids were old enough, they’d be fine, and it would have a big impact on my youngest son. Professionally, I realized that there are certain scientific projects that I was involved with that some of the junior people could take over, and that they could go on and run the project without me, and they would step up and grow into it. And that was useful because I then said “If they can do that, if something terrible happened to me, why don’t I have them do it now and move on to other things?” And that's what I've done. And now when I realize someone else can do something, I don't need to do it. I let them do it, and I do something else.

14. What makes you effective?
I have a couple of different strengths. I have pretty good skills as a physicist and have a pretty good understanding of physics. I’m pretty good at math, but I'm not a great mathematician. I’m good mathematician for a typical person on the planet, but would never be a math professor. I have pretty good verbal skills, pretty good communication skills, and I'm relatively good at EQ. Relatively good at picking up people's reactions to me and sensing what's going on. A skill that I've developed that is really helpful in leading groups is to not always feel I have to be…it’s not always about me. And then I understand that for other people, it's often about them. And then if you realize what someone's motivation is, you can figure out how you could work with them to achieve a goal. I find I try to understand what motivates other people, and that's helpful in working with them. I also have a pretty good scientific intuition. Given a partial picture, I can often guess the rest. I have the confidence to guess the answer sometimes and try to work towards it and often have the good sense that when my guess is wrong, I'm willing to abandon it.

15. Have you always had scientific intuition or is that something you developed over time?

That's something that's built up over time, but I’ve been helped by the fact that I had good mentors early who encouraged it. One of the things I learned from one of the people I worked with when I started as an assistant professor, she was a Postdoc at the same time I was, a woman named Graciela Gelmini. Graciela at the time went to work at Trieste, and when she went to work there, she talked to a guy named Dennis Sciama about how to be a good mentor. You’ve probably never heard of Dennis Sciama, but you've heard of his students: Stephen Hawking was a student, Roger Penrose was a student, Lord Martin Rees (who was head of the Royal Society) was a student, and the list just goes on and on…and what he told Graciela, and Graciela told me is the most important thing to give a student is love. If you give a student a sense of confidence, you give them the faith in themselves to try something exciting, they will do it. That the ability to believe that you can do something is one of the things that enables you to do something great.

This interview was conducted and condensed by Lisa Einstein '13