A Cambridge University Astronomy PhD, Dr. Scharf did his postdoctoral work at the Space Telescope Science Institute and the NASA Goddard Space Flight Center. He is now the Director of Astrobiology at Columbia University. His areas of research include the study of exo-planets and exo-moons plus an answer to the question of what sort of environments would support life elsewhere. His Life, Unbounded blog on the Scientific American network always makes for interesting reading. We asked Dr. Scharf to talk to us about his brand new book, Gravity’s Engines: How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Cosmos. The popular conception of black holes is as world-destroyers, but the newest evidence is forcing us to revise that conception. Would we even be around to wonder about the universe if it wasn’t for black holes? Join us for a fascinating chat.