Title: Scientific Discovery through Advanced Computing Abstract: The Scientific Discovery through Advanced Computing (SciDAC) initiative is a set of interconnected projects --- science, software development, and research to directed toward the latter --- designed to support simulation, data exploration, and collaboration in many thrust areas of the U.S. Department of Energy, including: climate modeling, fusion energy, chemistry and materials science, astrophysics, and high energy and particle physics. Lab and university-based SciDAC participants are creating a new generation of scientific simulation codes for terascale systems. The software spills over into many projects not officially in the SciDAC portfolio. This lecture briefly reviews the sweep of SciDAC and then focuses on some particular advances in the U.S. magnetic fusion energy program enabled by the introduction of solver software from the speaker's SciDAC project, Terascale Optimal PDE Simulations (TOPS, www.tops-scidac.org). Brief Bio: David E. Keyes is the Fu Foundation Professor of Applied Mathematics in the Department of Applied Physics and Applied Mathematics at Columbia University, an affiliate of the Computational Science Center (CSC) at Brookhaven National Laboratory, and Acting Director of Institute for Scientific Computing Research (ISCR) at the Lawrence Livermore National Laboratory. Keyes graduated summa cum laude with a B.S.E. in Aerospace and Mechanical Sciences and a Certificate in Engineering Physics from Princeton University in 1978. He received his Ph.D. in Applied Mathematics from Harvard University in 1984. He then post-doc'ed in the Computer Science Department at Yale University and taught there for eight years, as Assistant and Associate Professor of Mechanical Engineering, prior to joining Old Dominion University and the Institute for Computer Applications in Science & Engineering (ICASE) at the NASA Langley Research Center in 1993. At Old Dominion, Keyes was the Richard F. Barry Professor of Mathematics & Statistics and founding Director of the Center for Computational Science. Keyes is the author or co-author of over 100 publications in computational science and engineering, numerical analysis, and computer science. He has co-edited 8 conference proceedings concerned with parallel algorithms and has delivered over 200 invited presentations at universities, laboratories, and industrial research centers in over 20 countries and 35 states of the U.S. With backgrounds in engineering, applied mathematics, and computer science, and consulting experience with industry and national laboratories, Keyes works at the algorithmic interface between parallel computing and the numerical analysis of partial differential equations, across a spectrum of aerodynamic, geophysical, and chemically reacting flows. Newton-Krylov-Schwarz parallel implicit methods, introduced in a 1993 paper he co-authored at ICASE, are now widely used throughout engineering and computational physics, and have been scaled to thousands of processors.