NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This project was supported by the Department of Energy under Award No. DE-FG20-00ER54612. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the sponsors.

Front Cover: Background image: Hubble Space Telescope image of the Cygnus Loop—the shock wave from a 20,000-year-old supernova in the constellation of Cygnus. Courtesy of NASA. Inset images: the Z-Machine, courtesy of Sandia National Laboratories; the OMEGA laser, courtesy of the Laboratory for Laser Energetics, University of Rochester; and results from the first gold-on-gold collision experiments at the Relativisitic Heavy Ion Collider, courtesy of Brookhaven National Laboratory.

Back Cover: The target chamber at the National Ignition Facility, courtesy of Lawrence Livermore National Laboratory; and three-dimensional PIC simulation of a plasma wakefield accelerator, courtesy of R.Fonseca, Instituto Superior Técnico of Portugal, and the E-162 collaboration.