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 inspiral and merger of two black holes and the formation of relativistic jets by the black hole remnants of coalescing, magnetized, 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 numerical exploration of the cosmic censorship and "hoop" conjectures, and the demonstration that toroidal black holes can arise as transients during gravitational collapse. He was the first to calculate the radiation spectrum from spherical accretion onto a nonspinning black hole in general relativity. He and his collaborators coined the terms "supramassive" and "hypermassive" to describe two important classes of rapidly spinning neutron stars, whose properties they then determined. He helped develop the so-called BSSN formalism (named for Baumgarte-Shapiro-Shibata-Nakamura), now so widely adopted in numerical relativity. 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. Hans A. Bethe Prize, American Physical Society (2017) Amity High School Hall of Honor (2006) Fellow, Institute of Physics, U.K. (2004) Fellow, American Physical Society (1998) First Prize, IBM Supercomputing Competition (1991) Forefronts of Large-Scale Computation Award (1990) IBM Supercomputing Competition Award (1990) John Simon Guggenheim Memorial Foundation Fellowship (1989-90) Association of American Publishers Award (1984) Alfred P. Sloan Research Fellowship (1979)