My professional focus is on exploring and understanding the ephemeral, unseen Universe. I study phenomena that vary on time-scales of nanoseconds to years, such as fast radio bursts, the tidal disruptions of stars by supermassive black holes, neutron-star outbursts, the radiation statistics of astrophysical masers and lasers, and gravitational waves from binary supermassive black holes. I also seek to understand the distribution and physical nature of diffuse and hot matter around and in between galaxies.