Robie is primarily a gravitational theorist with interests ranging from quantum effects in gravity to horizon dynamics in black hole mergers. He has worked on horizon dynamics, black hole thermodynamics, gravitational holography, gravitational singularities, modified gravity, and quantum field theory in curved spacetime and its connection with entanglement. One of Robie’s primary interests is in understanding how the singularities of cosmology and gravitational collapse are influenced by quantum effects.