Gary Horowitz’s research centers on the classical and quantum aspects of gravity under extreme conditions, such as those inside black holes and the big bang — areas where Einstein’s equations break down and a quantum account of gravity is required. His work has helped bridge the gap between general relativity and string theory.

Horowitz played a pivotal role in the discovery of Calabi-Yau compactifications, which provide a mathematical framework for connecting higher-dimensional string theory to four-dimensional physical reality. He also helped develop models that integrate black hole physics with quantum theory, including work on the black hole information paradox.

His collaborations have launched new areas of research, including the gravitational nature of D-branes, the development of the AdS/CFT correspondence, and holographic models of superconductivity.