Interview with Steve Croft, Ph. D. on Black Holes

By Angel Zhou, Branson School

Black holes. Don’t let the name fool you: a black hole is anything but empty space. Rather, it is a great amount of matter packed into a very small area. Scientists can't directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. They can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby.

Steve Croft, an astronomer at the University of California, Berkeley, uses a new radio telescope, the Allen Telescope Array to study. He grew up in England, where he received a PhD in astrophysics from Oxford University in 2002, before moving to California to work as a postdoctoral researcher at the Lawrence Livermore National Laboratory.

Read the following interview to learn more about Dr. Croft’s life and work as an astronomer.  

Steve Croft, Ph. D.

1) How did you decide to enter your field of work?

I've always been fascinated to understand how things work. We're all born scientists and explorers at some level. Even as babies we learn about the world around us by trying things out, taking things apart, and performing experiments. I got particularly interested in space when a neighbor bought me a book about astronomy when I was probably about eight years old. My parents bought me a small telescope at about twelve that I used to look at craters on the Moon and the rings of Saturn. I continued to read astronomy books and watch astronomy TV shows, as well as being fortunate to learn math and science from some great school teachers.

I chose to study astrophysics for my undergraduate degree at University College London in the UK, and particularly enjoyed hands on experience with large telescopes at the University of London Observatory. That really confirmed for me that I wanted to be an observational astronomer, so I ended up doing a PhD at Oxford University, using some of the world's largest telescopes to study the growth and environments of supermassive black holes. I moved to California in 2002 and worked at the Lawrence Livermore National Lab for 5 years where I was a member of a small astronomy research group. I got to use the Keck Telescopes in Hawaii - the largest optical telescopes in the world - as well as the Hubble Space Telescope and many others. I've been at Berkeley since 2007, and I'm currently working on one of the most cutting edge radio telescopes in the world as part of a big international team. 

2) Describe your typical day at work as an astronomer. What are your favorite and least favorite parts of your job?

I travel a lot for work. I just got back from a month in Australia. I spent most of the time there working with colleagues at the University of Sydney, but I also traveled to Melbourne for a couple of days to give talks, as well as out to the site of the telescope I'm working on, in the remote Australian outback. Last year I traveled to South Africa and Italy for conferences, as well as several trips within the US for meetings. The travel is one of my favorite parts of the job. Meeting new people and exploring new ideas, as well as seeing new places, are important to me.

When I am in the Bay Area I go into the office most days, although sometimes I work from home or have meetings offsite. I work in a regular office which I share with another astronomer. Most of my work is done using an iMac computer with two big screens, but I log in remotely to more powerful computers (including one with 256 GB of RAM and many TB of storage) to analyze the data from the telescopes I'm using. More often than not I'll have a meeting or two, or attend a seminar. Sometimes I'll have informal discussions with colleagues over lunch. I read papers written by other astronomers to keep up on research in my field. I also do a lot of education and outreach programs, including working with high schoolers. Last year we launched two high altitude weather balloons with GoPro cameras attached to the edge of space. That was really exciting.

I guess my least favorite part of the job is that I always have so much going on, including a ton of emails waiting for me to respond to. It's great to be in a job that's stimulating but sometimes I feel like I will never get to the bottom of my to-do list.

4) What are black holes and why do they play an important role in the universe?

There are two main varieties of black holes. One kind is about the same mass as our Sun. These result from the violent deaths of massive stars. There are probably millions of these in our Galaxy. The other kind, the ones that I research, are supermassive black holes that can be millions or billions of times as massive as the Sun. These monsters lurk at the centers of galaxies, typically only around one per galaxy, and we're starting to understand that the way they get to be so big has a profound influence on the galaxies themselves. The forces that they produce are so incredibly powerful that they can rip stars apart and send out blast waves that shape the gas and stars that make up the galaxies in which they live.

5) What aspect of black holes are you particularly fascinated by and why?

One thing that I'd like to understand better is why some black holes lurk around not doing very much, sometimes for billions of years, and then switch to violent phases of growth. Understanding how they launch jets of material moving at close to the speed of light, and how collisions of black holes disturb spacetime itself, are areas of active research that I hope we'll get closer to understanding with the new generation of telescopes that we're building.

Join us on Wednesday, March 11th for Steve Croft’s seminar, "Snacking, Gorging, and Cannibalizing: The Feeding Habits of Black Holes" of UC Berkley in Room 207 at Terra Linda High School in San Rafael. For more information, visit Marin Science Seminar's Facebook page: https://www.facebook.com/events/1540138222921928/.