Sweet home Chicago

By Diana Steele
News Office

Stephan Meyer, Professor in Astronomy & Astrophysics, the Enrico Fermi Institute and Physics and Director of the Center for Astrophysical Research in Antarctica, never expected that he would end up back in Chicago 23 years after he left Hyde Park to go to college.

When Stephan left home in 1970, he wasn't intending to study physics, let alone become an experimental physicist like his father, Peter Meyer, Professor Emeritus in Physics, who has been a University faculty member since 1953 -- the year Stephan was born. Now he has an office down the hall from his dad in the Laboratory for Astrophysics & Space Research, and he uses giant balloons, like his father, to study astrophysical phenomena above the earth's atmosphere.

Stephan is the principal or co-investigator on no fewer than three ambitious projects to map the cosmic microwave background: Top Hat, a balloon-borne detector that will be launched in Antarctica in 1999; MAP, a NASA satellite that will be launched in 2000; and Planck, a European Space Agency satellite to be launched in 2005.

He graduated from the Lab Schools in 1970 and received his B.A. from the University of Wisconsin-Madison in 1974 and his Ph.D. in 1979 from Princeton. He was a postdoctoral associate and then assistant professor of physics at MIT before joining the Chicago faculty in 1993.

What was it like to come back here, after being gone for so many years? I never intended to end up at Chicago. But I was very interested in the cosmology here, and the theorists here were interested in adding more experimentalists, so it was a very good fit. I walked around for a few months with a weird feeling, after having been gone so long. I also had to get over feeling like a kid again, since some of my dad's colleagues, whom I had met as a child, were now my coworkers.

What are your memories of being a child growing up around physicists? I got to know some of the people my dad worked with, but I didn't hang out in the lab. I do remember someone who came to visit when I was about 10 years old. One of the things we used to do when I was a kid is go to the sand dunes in Michigan and slide down the sides of them. This guy, Kip Thorne, who must have been a postdoc at the time, came to the dunes with us, and he impressed me incredibly because he did cartwheels down the side of the dunes! Now, of course, I'm impressed with the science that he's done [Thorne, now at Caltech, is a noted physicist and author]. But in my mind, that will never beat the fact that he did cartwheels!

How did you get interested in physics? When I went to college, I thought that I was going to go into chemistry. But then I didn't do so well. I took physics the second year, and it was relatively easy and fun, and I liked it. Early on, I joined a research group, and I realized I really liked lab work. I drifted into the business because I spent a lot of time in the lab and lived in the culture. It was my dad who made me aware that being a student tech was something I could do. He didn't push me, but I never would have realized that on my own, so in a sense he got me started.

How did you start working with balloon experiments? I actually did my thesis on a telescope on the ground, measuring the redshift of high redshift galaxies. At MIT as a postdoc, I joined a cosmic microwave background group working with balloons. So it's sort of by chance that my dad's working on balloons and I'm working on balloons. It was a very circuitous route, and that I ended up doing it myself was a bit of a surprise. But here I am at Chicago, doing balloons -- with everyone down the hall doing balloons, including my dad. They're pretty different payloads but they're still balloons, nevertheless.

What are the questions you are trying to answer? The basic question is, how did structure -- galaxies and galaxy clusters -- form in the Universe?

We're coming to the point in cosmology where theorists have made extremely precise predictions that experimentalists, like myself, can actually measure and test. Cosmology used to be a field of nuts -- theorists could make whatever predictions they liked because you couldn't measure them. But things have changed -- David Schramm did calculations on Big Bang nucleosynthesis that have been compared with measurements. Anisotropy in the cosmic microwave background was predicted and then seen in 1992.

Now there are a dozen experiments that have measured the cosmic microwave background on some scale, and a dozen more that are being built now. Comparing the results of these experiments, like the three I'm working on, will make it possible to answer fundamental questions long-held in astronomy, such as: Is the Universe going to expand forever or collapse in on itself? What is the expansion rate, the Hubble constant, of the Universe? Is there a cosmological constant? It turns out that all of these questions come into the models and we'll be able to extract the numbers.

In five to 10 years, we'll be able to get a precise handle on the models or show that they're not correct. Either way, it's fine with me.

It sounds like you've got things pretty well mapped out for yourself through 2005, when Planck is launched. What's next?

The cosmic microwave background field may be very different in 10 years or so. If the models fit very nicely to the actual measurements, then it will be down to details, whether, for example, the Hubble constant is 46.1 or 46.2. On the other hand, it could be the models still don't work, and whether I stay in the field, and whether it stays interesting, depends on how these things develop.

If it comes to digging precision answers out of galactic dirt, I'm not going to be the one doing it. It's just too fussy. This field is interesting now because it combines fundamental questions and really neat experiments on a scale that is still human.

This generation of experiments has to be played out before we'll know where to go next. So far in this field, every experiment has opened up a whole new set of burning questions.