Astrophysical shocks are among the most powerful particle accelerators in the Universe. Generated by violent interactions of supersonic, and often relativistic, plasma flows with the ambient medium, shock waves involve a complex and highly nonlinear interplay between the dynamics of flows, magnetic fields, and accelerated particles through mechanisms not yet fully understood. “What is the origin of cosmic rays?”, “What controls particle injection and the acceleration efficiency in collisionless shocks?”, “How is the physics of relativistic shocks modified by electron-positron pair production?”, “Can these mechanisms be studied in the laboratory?” These are long-standing scientific questions, closely tied to extreme plasma physics processes, and where the interplay between micro-instabilities and the global dynamics is critical. Advances in high-power lasers and particle beams are just now opening unique opportunities to probe the microphysics of shocks and particle acceleration in controlled laboratory experiments for the first time. Together with the fast-paced developments in fully-kinetic plasma simulations, computational power, and astronomical observations, the time is ripe to deploy a research program focused on particle acceleration in shocks that can transform our ability to address these questions. We aim to use first-principles massively parallel simulations and laboratory experiments to study the microphysics of non-relativistic and relativistic shocks, and to use data-driven techniques to develop multi- scale models that bridge the gap between the microphysics and the global dynamics. This project will build comprehensive models of the plasma processes that shape magnetic field amplification, particle acceleration, and radiation emission in shocks, with the goal of solving central questions in extreme plasma phenomena, opening new avenues between theory, computation, laboratory experiments, and astrophysical observations.
