Questions and answers with Gary G. Tibbetts
George Rieke is Regents' Professor of astronomy and planetary sciences at the University of Arizona in Tucson. He completed his bachelor's degree in physics at Oberlin College in Ohio and his master's and PhD degrees, also in physics, at Harvard University in Cambridge, Massachusetts. He is a member of the American Academy of Arts and Sciences and of the US National Academy of Sciences.
Soon after completing his PhD thesis in 1969 on TeV gamma-ray astronomy, Rieke switched to IR and submillimeter astronomy, which he covers in his first book, Detection of Light: From the Ultraviolet to the Submillimeter (see the review in Physics Today, December 1995, page 70). His second book, The Last of the Great Observatories: Spitzer and the Era of Faster, Better, Cheaper at NASA (University of Arizona Press, 2006), draws on his role as principal investigator of the multiband-imaging photometer for the Spitzer Space Telescope. Now, he is science team lead for the mid-IR instrument for the forthcoming Hubble Space Telescope replacement, the James Webb Space Telescope.
Physics Today recently caught up with Rieke to discuss his latest book, Measuring the Universe: A Multiwavelength Perspective (Cambridge University Press, 2012).
PT: What motivated you to write this book at this point in your career?
Rieke: I have taught a graduate instrumentation course for many years and was frustrated that there was no suitable text. My goal was to succinctly cover the central techniques utilized across the entire electromagnetic spectrum. This goal reflects three realities: Astronomers increasingly make use of data obtained by a large variety of instruments; they should have some understanding of how the data were obtained; but graduate school curricula do not allow for in-depth study of all these instruments.
My challenge was to select the topics and priorities to include techniques many astronomers will confront in their careers without dragging in highly developmental areas that might not turn out to be important. I kept the discussion to general principles and avoided the details of specific instruments except as illustrations, since specific instruments typically have extensive descriptions available over the internet. The book should provide the basis for courses, with the expectation that teachers will supplement it with additional material in areas of personal interest. I also recommend it to researchers who want a broad overview of the huge variety of data sources in modern astronomy.
PT: What has been the most disruptive technological advance since you first entered astronomy, and how has it changed the field?
Rieke: The most disruptive recent advance, although it predated me, was radio astronomy. It opened our eyes to the rich universe of sources not associated with normal stars, so it had implications beyond astronomy and into popular culture—where would we be without quasars and supermassive black holes?
I was privileged to participate fully in a similar advance—the development of infrared astronomy. The original breakthroughs were made with single detectors, but the sky was supersaturated with new things to discover and even one detector was enough. However, the application of arrays of infrared detectors pushed this spectral region onto center stage for astronomy in general. The appreciation for the infrared sky revealed by these arrays has made the JWST the primary mission for space astronomy in this decade. From when I entered infrared astronomy to when JWST is operational nearly 50 years later, the Moore's Law doubling time for capability in infrared astronomy will have been only ten months!
PT: What technological advance is now needed to take the field to the next level?
Rieke: We have been spoiled over the past 60 years. Technology advances such as infrared detector arrays, radio aperture synthesis, computer power, and space telescopes have made us think that revolutionary gains are the norm. Nonetheless, there are more major advances coming, such as very large—of order 30-meter aperture—ground-based telescopes, new high-contrast imaging techniques (for exoplanet searches), sophisticated adaptive optics, advanced gravity-wave detection, the JWST, and ALMA, the Atacama Large Millimeter/submillimeter Array.
However, the largest potential for a real paradigm shift is time-domain astronomy, with telescopes such as Pan-STARRS (the Panoramic Survey Telescope and Rapid Response System) and eventually the Large Synoptic Survey Telescope, which, combined with state-of-the-art computer power to sift through immense amounts of data, may chance on new phenomena that are currently unimagined. A space-based gravity-wave detector would have similar potential.
PT: How will the JWST utilize the technologies discussed in your book?
Rieke: Traditionally, conservatism in the development of space missions results in utilizing technologies that are a few generations old by the time of their launch. JWST is different. By making major investments early on in advanced technology to enable new capabilities, it will still have state-of-the-art capabilities upon launch. This extends to all of its detector arrays, to the integral field-unit spectrographs, to its multi-object spectroscopy, and to high-contrast imaging including non-redundant masking and coronagraphs.
PT: How do instrument developers work with experimental astronomers and theorists and cosmologists in equipment design?
Rieke: The approach has evolved. In my youth, many instruments were built by one or two people who just wanted to do a science project: Once, we put a new one together to resolve a conflict in the telescope scheduling. As instruments grew in complexity, there was a tendency to build small teams of engineers that were given specifications for an instrument by a few interested scientists, most of whom then left the engineers to complete the job. My feeling is that now, with instruments of even greater scope and cost, a team of scientists must be deeply involved to write the proposals needed to get started, and even more to monitor the compromises that must inevitably be made when the available resources confront reality.
PT: What books are you currently reading?
Rieke: I seem to be continuously reading the Arxiv astrophysics section, but I suppose that does not count. I love travel and books associated with places I might visit. I just finished Following Mateo: Two Years Searching in Belize (Trafford Publishing, 2006) by Tom Molanphy, a fascinating account of current-day Mayan culture from the perspective of a Canadian teacher and church representative, enlivened with self-deprecating humor. Previously, I was gripped by In the Shadow of the Banyan (Simon and Schuster, 2013) by Vaddey Ratner, an almost too vivid fictionalized account of the author's experience as a child in the Khmer Rouge revolution in Cambodia.