From APS’s Physics, Jan. 29, 2019: On Jan. 9, a handful of researchers with the Dark Energy Survey — one of the most ambitious attempts to probe the dynamics of the universe’s expansion — headed to the control room of Chile’s Blanco Telescope. For one last time, they opened the white telescope’s dome. From their perch overlooking the red Andean Mountains, they set up for a night of observing the southern sky.