Q&A with Mark Devlin
The night sky is beset with innumerable stars, equally dazzling and dim, intermittent asteroids, comets, and meteors, planets gaseous and telluric, and our inconstant moon that changes monthly in her circled orb.
An array of these distant objects can be viewed with the naked eye, their supernatural beauty often evoking sublimed awe.
Mark Devlin, the Reese W. Flower Professor of Astronomy and Astrophysics in the School of Arts & Sciences, observes the night sky with the whetted sight of a veteran cosmologist, and sees not merely beauty high up above, but wonder.
“Most people look up there and see stars,” he says. “When I look up there, I see something completely different. I’m looking at how things are connected, the connection between galaxies, the connection between stars, and how did they get there.”
A physicist like his father before him, Devlin says he has always been interested in astronomy. As an undergraduate at the University of Wisconsin—where he studied physics and math—he conducted research in an X-ray astronomy laboratory, exploring the afterbirth of supernovae. He went on to receive his master’s and Ph.D. in physics from the University of California, Berkeley.
As an esteemed experimental cosmologist who designs and builds the instrumentation to study cosmology at millimeter and sub-millimeter wavelengths, Devlin’s research has taken him south to West Virginia, farther south to New Mexico, even farther south to Chile, and all the way to the southernmost part of the Earth—Antarctica and the South Pole.
“The fundamental models for cosmology have been remarkably robust over the last 10 years,” he says. “We have a very, very good understanding of how to represent the universe. What we’re doing now is we’ve made predictions about the very early universe, the first instance after the Big Bang. That’s the one big thing that people are looking for now. It’s called gravitational B-mode for slang, but it’s basically observing the first instant in time after the birth of the universe.”
The Current sat down with Devlin in the David Rittenhouse Laboratory to discuss astronomy versus cosmology, a cosmologist’s definition of the universe, near-space NASA balloons, and jogging in Antarctica in a T-shirt.
Q: Would it be accurate to define astronomy as the study of stars, planets, and other objects in outer space, and cosmology as the study of how the universe came into being?
A: Astronomers will study objects or classes of objects, and try to figure out the details. If you study Mars, you’re studying Mars as one object. If you’re studying a certain type of star, then you’re studying that object. Cosmology is more a statistical study of the universe. You’re not really interested in one thing; you’re interested in the whole thing as a system. The universe started out incredibly smooth when it was first born—smooth meaning, if you just moved from place to place in the universe, it’s exactly the same to about one part in 100,000, even several hundred thousand years after the Big Bang. But if you look at our universe today, you’re sitting on the Earth and it’s a rather ordered object. It’s a sphere. If you go next to the Earth, there’s nothing. There is a lot of stuff in our solar system, but if you go next to our solar system, there’s nothing. Those are big deviations in the amount of matter, and you can extend that to talking about our galaxy. Next to our galaxy, there is nothing, but there are galaxies nearby our galaxy, and there is just space in between. This hierarchical structure extends up to really, really large scales—a billion light years or more. One of the things cosmologists do is try to understand how all of that came into being. What are the parameters that affect the evolution of the universe from being very smooth to the universe being very ordered? You might make an analogy that you could show a person a fetus and you could show them a 98-year-old person and they might say, ‘Well, they hardly look related at all.’ They are different sizes, different shapes, but you can kind of see that they are made up of the same stuff, and they have maybe the same kinds of basic things going on, but you don’t know how they got from A to B. But if I showed you a football stadium full of people that had a cross section all the way from babies to older people, then you might say, ‘OK, now I understand. I see that there’s this evolution that takes place, there’s a growth that takes place, people go from being an infant, to being an adolescent, being a teenager, to being middle age, and so forth.’ Then you could come up with a theory that would allow you to say that is how people grow because you have nailed it down at many different spots along the line. It is basically the same thing with the universe.
Q: When you talk about the universe, how do you define it? Is it everything that exists?
A: Well, the universe is a tough one. There’s the visible universe, what we can see, but then there’s the part of the universe that we can’t see, and let me be very specific about that. We can only see photons that have been traveling since the universe was born, and that’s 13.7 billion years ago. So I can see 13.7 billion light years in one direction, and I can see 13.7 billion light years in the opposite direction. Now place yourself in a galaxy that is a billion light years in a different location from us. Well, they can also see 13.7 billion years in either direction. This means that they are looking farther in the direction they are offset from us. So my visible universe is only as big as I can see, but that doesn’t mean that the universe itself isn’t bigger than that, it’s just that we can’t see it now. And every year, the visible universe gets one light year bigger because a year more of light travels. But in general, we talk about what it is to be in the universe that I can measure, that I can see.
Q: You mentioned that your father was a high-energy physics professor at Rutgers University. Did your father’s work have an influence on you becoming a physicist?
A: Sure. He did a lot of research and I saw what he was doing all the time. I thought that was fun, but high-energy physics involved very, very large collaborations—hundreds of physicists involved in one result. Astrophysics is still a small number of people, so it’s a much more intimate group of people working on what I would consider fun projects. I went to graduate school at Berkeley thinking that I was going to be a high-energy physicist like my father. But because of my astrophysics work as an undergraduate, my eventual adviser at Berkeley recruited me away and convinced me to do astrophysics instead, which, of course, was good news for me. I wouldn’t have enjoyed high-energy physics in retrospect.
Q: If someone wants to be an astronomer or cosmologist, does he or she have to be good at math?
A: Usually. I think that certainly in high school, you need to be taking a lot of math. There is a lot of catch-up to start a degree in physics without a good math background, even as an undergraduate. The majors like physics, and math, and biology, and chemistry don’t leave a lot of room for completing them in four years if you don’t have the preparation from high school. Physics, I think, is especially rigorous in that way. You have to be prepared from the get-go because the introductory physics classes use calculus right away. The only reason I got a math major was because you had to take so many classes to be a physics major and it was only two more classes to get the math major, so I just did it.
Q: One of your research projects is the NASA high-altitude balloon BLAST: Balloon-borne Large-Aperture Sub-millimeter Telescope. During an interview on ‘The Colbert Report’ in 2009, you said BLAST is a ‘balloon-borne telescope that goes up above the atmosphere to get a peak at the early universe.’ How does BLAST work?
A: The basic idea is that if you look at the stars in our galaxy, they must have been made somehow. And if you just take the number of stars and divide by the age of our galaxy, you can get a rate at which stars must have been formed, or put a constraint on that, and you find that the number of stars being created today is far less than it must have been in the past. This leads us to conclude that galaxies were different in the past. We are now kind of a middle-aged galaxy. Back in the day, when we were an adolescent galaxy, we were forming stars at a much higher rate, and BLAST was looking for the evidence for that, tracking the evolution of how stars were being formed over many billions of years.
Q: BLAST studies thermal emission from galaxies 7-10 billion light years away. When you talk about light years, can you give a sense of how far away that is?
A: It’s a long way. You basically take the speed of light in meters per second and multiply it by the number of seconds in a year. It’s a distance. To put it into perspective, the nearest star is about three light years away, which is pretty far. If you think about it in terms of the size of our solar system, Neptune, which is the farthest planet from the sun, is about 40 times the distance that the Earth is away from the sun. That means that in light minutes, it is 320 light minutes away, so that’s about five hours. So you could say Neptune is about five light hours away, whereas the nearest star is three light years, to put it in scale. It’s a long way away to get to the next planetary system.
Q: You launched BLAST, which reached rear-space at 125,000 feet, from Antarctica in 2006. Why Antarctica?
A: A couple reasons. First of all, the balloon has to go up and then it has to come down. You wouldn’t want to fly it over, say, people. It weighs 5,000 pounds, so it’s like dropping a car down onto someplace and it’s not particularly well-controlled. When we fly it from North America, we normally fly it from the middle of nowhere in New Mexico. As long as you don’t land it near a town, you’re pretty safe. The problem with North America is that the wind takes you away from where you are, and eventually [BLAST] goes out of range and it might go over the ocean and you may never get it back. And certainly you can’t just willy-nilly fly around the Earth. People get upset when you fly over their country. The other issue is that as the sun rises and sets, the balloon goes up and down. We can compensate for this by dropping ballast, but eventually we run out. When you fly from Antarctica in December, the sun is up all the time. The other reason why we chose Antarctica is because we use solar panels and having the sun up all the time gives us continuous power. Finally, when you drop the balloon, there’s nobody there. You drop it on the ice and you just go pick it up. It’s not that easy, but at least you don’t hurt anybody on the way.
Q: How long did it take you to get to Antarctica?
A: You fly to New Zealand, and then you wait about a day or two. If the weather is good, you then go down in a military transport and it takes you to McMurdo Station. It’s about a six- or seven-hour flight. It’s not so bad. We’ve been there three times so far.
Q: Was it cold?
A: Not really. I’ve jogged in a T-shirt.
Q: In Antarctica?
A: Yeah, on the ice. The difference is the sun is up and it’s pretty intense and there’s ice everywhere. You’re running on snow and ice. The sun is reflected all around you. As long as it’s not windy, it’s not all that bad—in the summer. Of course, in the winter, it’s very cold. We launched relatively near the coast. I’ve only been to the South Pole once, just last year. It’s colder there.
Q: Is the BLAST project still ongoing?
A: We shifted gears with BLAST about three years ago and we decided to start observing star formation in our own galaxy. Before, we studied star formation in distant galaxies. We’ve figured out that we can make BLAST sensitive to what regulates the rate that stars form and how many stars are being formed. Something is regulating it; something is keeping the stars from forming faster than we think they should. We believe that galactic magnetic fields might be regulating star formation. We modified BLAST to make the measurement, ran some tests during two flights in 2010 and 2012, and presented our findings to NASA. They funded a $5 million grant to build a new BLAST that’s bigger and better. We’re in the process of building it with a whole bunch of graduate students at Penn.
Q: With colleagues across the globe, you are also working on the Atacama Cosmology Telescope in Chile—the highest observatory in the world—that is also studying how the universe began and evolved. Can you talk a little bit about that project?
A: That project is very active right now. That one is, again, looking at the early universe, the cosmic microwave background. We commissioned it in 2006 with our first camera. Now we have our second camera on it and that is going to be fully operational during the summer. We take a lot of trips down to the Atacama in Chile, which I would say is harder to work in than Antarctica by quite a bit.
Q: Why so?
A: Antarctica is run by the National Science Foundation and they have a big huge base down there and it’s like having your mother take care of you. They cook all your meals, they drive you around. All you do is work, and all the logistics and everything is taken care of. In Chile, we’re on our own. We’re in the middle of the mountains, a very, very remote mountaintop at 17,000 feet. It can be cold there, too, and windy, and there’s not very much oxygen. I’m a pretty decent diesel mechanic now. You have to bring your own generators, and you have to refuel, and you have to drive up the roads. It’s a huge amount of work. But it has a lot of advantages over Antarctica in the sense that you can get there anytime and you have access to more of the sky. It’s high. It’s not quite like being in a balloon, but it’s still pretty good. At 17,000 feet, half of the atmosphere is gone, so there is half as much pressure, half as much oxygen. The Atacama is also known as the driest place on the planet, so it’s extremely arid. Water is particularly bad for being able to see through at millimeter wavelengths. It’s got to be high and dry. We’re constantly upgrading the telescope. In fact, we’re writing a new proposal right now to make it even better by adding a third camera. We’ve been very successful with that and are pushing the boundaries.
Q: I understand that you worked with Jackie Tileston, an associate professor of fine arts and painting at PennDesign, her husband, and Benjamin Schmitt, a Ph.D. student in physics at Penn, to create the ARTacama Project, an art installation on the Atacama telescope.
A: Yes. Our cameras are big pieces of equipment. They are like the size of an oil drum. They’re very expensive and we have to keep our detectors at a fraction of a degree above absolute zero. They’re like big thermos bottles—very, very expensive and complicated thermos bottles. Whenever we buy a new camera, we choose a color, and I chose poorly last time: yellow. I’m not quite sure why. We decided to see if any undergraduates wanted to do an art project to paint it. Surprisingly, no undergraduates really wanted to do it, but Jackie, who is obviously a very accomplished artist, said, ‘Oh yeah, I’ll do it.’ She and her husband talked to us and learned about the science and understood the theme, and basically adapted her artwork, her style, to create a rather large, wall-size painting. She then got a grant from the Department of Fine Arts to have it turned into a sticker, like the ones they wrap around buses. A company came in, measured the camera, and then took a high-resolution image of her painting and put it on a sticker. We then came in and covered the whole camera and took it to Chile, and I think we now have the highest art installation in the world.
Q: You are the principal investigator of the National Radio Astronomy Observatory’s Green Bank Telescope located in the United States National Radio Quiet Zone in West Virginia. What is the Green Bank Telescope searching for?
A: The Green Bank Telescope is a much bigger telescope than the Atacama telescope. The Green Bank Telescope is the largest point-able object on land. It’s 100 meters [around 328 feet], so it’s bigger than a football field. We built a very specialized camera for that. We’re building a new one, which is just about done, and that one will go on in the fall. That one is looking at the largest gravitationally bound objects in the universe. These are not solar systems or galaxies, but clusters of galaxies that have come together into one big grouping. These things can have a million-billion times the mass of our sun, so this is a really, really big thing. We study them, and the details of their structure, and how they formed.
Q: Why are you so fascinated by the origins of the universe?
A: How could you not be? It’s a pretty fundamental question. Knowing how things evolve is pretty fun. I think that with most scientists, the thrill is now knowing something that nobody has known before, and you’re the one who figured it out. Most of what scientists do is relatively dull, but occasionally everybody has at the very least a minor ‘A-ha’ moment where they discover something new and understand something better. And occasionally somebody comes up with something that is really fundamental and helps everybody understand everything better. That’s kind of what drives you, finding something new.
Q: How much do astronomers and cosmologists know about space? The multi-national ATLAS experiment discovered the Higgs boson—the so-called ‘God particle’—in 2012 that is said to be changing our understanding of the world.
A: I think we know a lot more than we did before, but I think there are a lot of things that we just have no idea what they are. For example, the matter that makes up all the planets and stars in the universe—hydrogen, helium, carbon, and all the elements—they only make up a tiny, tiny fraction of our universe. The heavier elements that make our planet are even rarer. There is hardly any rock and metal in the solar system compared to the sun, which is basically all hydrogen and helium. However, if you look at what makes up the universe as a whole, there’s this stuff called dark matter, and there is 10 times as much dark matter out there as there is hydrogen and helium. And then on top of that, the rest of the stuff is called dark energy. If you divide the pie up, it’s about 70 percent dark energy, about 26 percent dark matter, and about 4 percent regular matter, and what makes up the Earth is a tiny fraction of regular matter. We know that dark matter exists, or something like dark matter exists, but we don’t have any idea what it is. We have speculations, but nobody’s measured dark matter. We can’t see it, and we can’t touch it, and we can’t hold it, but we can see its effect on the large-scale motion of galaxies. That’s kind of fun. And then there’s this stuff called dark energy, which is really screwed up, because dark energy is basically making the universe fly apart faster. The universe is not only expanding, but it’s an accelerating expansion, it’s getting faster, and faster, and faster due to dark energy, and we don’t know what it is. Mathematically, people have written stuff down, but we’re still just trying to characterize it and where it comes from and so forth. In the end, we really don’t know what most of the universe is. We’re just starting to scratch the surface of understanding that it’s there, but when you look up at the night sky, all you see is the stars and some galaxies. You are only looking at 4 percent of the universe; you’re not seeing the other 96 percent. The study of the 96 percent is going to be really pretty fundamental.
Q: Are you still biking to campus from your home in Wynnewood?
A: I biked this morning. [When the city was draped in inches of snow and ice.]
Q: It’s about a 16-mile round trip?
A: More like 15, but yeah.
Q: And you run in sometimes, as well?
A: The weather has been so bad that I haven’t run in in awhile. The problem with running is I bring my laptop back and forth. You can’t run with a laptop on. If I’m going to run in, I have to plan the day before and leave my laptop at work and accept that I’m not going to get any work done that night, which is very difficult for me to do. On weekends, I’ll run in because my parents live downtown so I’ll go visit them. But I haven’t run in to campus probably for two months. I prefer to ride.