“Dark Energy” refers to a mysterious effect in the largest, emptiest stretches of the cosmos, that causes the expansion of the universe to accelerate.
The mystery of dark energy reminds us how profoundly we do not understand basic physics of space and time at a deep level. Roughly speaking, the current theory is that “Space-time tells matter how to move, and matter tells space-time how to curve”. But how do such fundamentally different things talk to each other?
Fermilab’s dark energy experiments address this mystery with precision measurements based on massive cosmic surveys that probe the nature of matter, space-time, and their interactions on the largest scales. The Dark Energy Survey (DES) operates a large CCD camera on the 4m Blanco telescope at CTIO in Chile in order to capture images of a large swath of the sky and study them in order to extract a detailed understanding of the effects of dark energy. The Rubin Observatory Legacy Survey of Space and Time (LSST) will execute a similar survey but on a much larger scale, with a new telescope to be built in Chile. Finally, the Dark Energy Spectroscopic Instrument (DESI) will deploy an instrument on the Mayall telescope at Kitt Peak (Arizona) to make precision spectroscopic measurements of the colors of distant objects, providing information about the nature of dark energy further back in time.