Professor Shapiro has broad research interests that span many areas of theoretical astrophysics and general relativity theory, including the physics of black holes and neutron stars, gravitational collapse, the generation of gravitational waves, and the dynamics of large N-body dynamical systems. His research emphasizes the use of supercomputers to solve long-standing, fundamental problems in numerical relativity and computational astrophysics. Shapiro has worked on the theory of accretion onto compact objects, relativistic stellar dynamics, gravitational collapse, binary black hole and neutron star inspiral and coalescence, the generation of gravitational waves, the formation of black holes, Big-Bang nucleosynthesis and neutrino astrophysics, to name a few topics. Some of his most important simulations include the emitted radiation spectrum from gas accreting onto black holes and neutron stars, the disruption and consumption of stars in star clusters containing a central supermassive black hole, the formation of a supermassive black hole at the center of a galaxy or quasar from the collapse of a relativistic collisionless gas, the head-on collision and merger of two black holes, and the gravitational wavetrain from the late inspiral of coalescing binary neutron stars. He merged the fields of stellar dynamics and numerical relativity, a development which led to the simulation of the catastrophic collapse of an unstable, relativistic cluster to a black hole, the demonstration that toroidal black holes can arise as transients during gravitational collapse, and the possibility that naked singularities might form during the collapse of collisionless matter from reasonable initial conditions, thereby violating cosmic censorship. Long interested in the future detection of gravitational waves by laser interferometers like LIGO and LISA, Shapiro and his group are working on the theory of gravitational wave generation and the identification of promising astrophysical sources.

Professor Shapiro's deep interest in training young scientists has given him a reputation as an inspiring and effective classroom teacher and research advisor. He has created and taught over a dozen courses in physics and astrophysics. The textbook that he coauthored, Black Holes, White Dwarfs and Neutron Stars: The Physics of Compact Objects (John Wiley, 1983) is a standard in the field. His research has led him to develop numerous videos of his computer simulations, which offer both great technical insight to experts and qualitative understanding to non-specialists. He leads a vibrant group of graduate students and postdocs working in theoretical astrophysics and general relativity. For over two decades he has trained an expert team of advanced undergraduates doing research in theoretical astrophysics and general relativity by means of supercomputer simulation and visualization. His undergraduate research program is among the most successful in the nation; members of his team are highly sought after by the most select graduate programs in physics, astronomy, computer science, and related areas.