The universe is expanding, and the rate of expansion is accelerating. A mysterious effect appears to be counteracting gravity and pushing matter apart. This is attributed to "dark energy" which is estimated to make up 68 percent of all energy in the universe. Despite its prevalence, very little is known about dark energy. CHIME has been designed to learn more about dark energy by measuring the expansion of the universe over a period in the distant past when its effects first became apparent.