Composite by Jenny Somerville. How Caltech researchers blend fields and scientific approaches to achieve results. By Ker Than Theoretical physicist Kathryn Zurek has dedicated much of her professional life to trying to solve the riddle of the universe’s missing mass, also known as dark matter. In her view, dark matter could be far richer than many theorize—not a single particle but an entire “shadow world” with its own variety of particles and forces. Her proposal fits within the standard model