What is the universe made of? Experts weigh in on the mysterious force that shapes our cosmic history

As the Dark Energy Survey (DES) releases its final results, we caught up with two physicists who've been involved in the project from its early days. In this Q&A, Josh Frieman, DES co-founder and associate laboratory director for fundamental physics at the Department of Energy's SLAC National Accelerator Laboratory, and Risa Wechsler, director of the Kavli Institute for Particle Astrophysics and Cosmology, discuss what the decade-long effort taught us and how it prepares us for the NSF–DOE Vera C. Rubin Observatory's 10-year mission to explore some of the universe's biggest mysteries.