Neutrinos are now being observed by the 10-meter South Pole Telescope. Neutrinos are thought to be dark energy or energy without mass. Under Einstein's cosmology constant, neutrinos are considered the energy amongst empty space, which now explains the acceleration of the expanding universe. The SPT is designed to focus on the light after the big bang, also known as cosmic microwave background radiation. They look at this to find galaxy clusters to try to find the mass of the neutrino.

The South Pole Telescope is used to put constraints on dark energy in order to see its mass. "The results are based on a new method that combines measurements taken by the SPT and X-ray satellites, and extends these measurements to larger distances than previously achieved using galaxy clusters." Galaxy clusters leave behind shadows when cosmic microwave background radiation is passed through it, which lets astronomers see the most massive clusters in the universe.


http://www.sciencedaily.com/releases/2012/04/120402093153.htm