One of nature’s biggest mysteries, dark energy, is being explored thanks to a deceptively simple tool that David Schlegel came up with. 2,200 aluminum plates, about the size of a manhole cover, each one drilled with a specific pattern of holes that match the arrangement of galaxies in a particular section of the sky, are used for an hour each at the prime focus of the 2.5-meter telescope at Apache Point Observatory in New Mexico. When the telescope points to the right spot, the light from each galaxy streams through its corresponding hole. This light is then broken up and used to measure how fast each galaxy is being carried away.
Read more @ SciTechDaily