What is dark matter and dark energy? Dark matter and dark energy are two unknown things. Dark matter is a substance in the universe that keeps things together by using its mass to bend spacetime, hence creating gravity to keep things like galaxies together. Dark energy, however, is the exact opposite of dark matter. It is an unknown substance which pushes things away from each other. These forces have been in existence since the beginning of our universe and they engage in a cosmic dance that determines the fate of our universe. The story of dark matter Dark matter was the first of the two to be discovered. One day in the 1970s, at the Kitt Peak National Observatory located 56 mi (90 km) southwest of Tucson, Arizona, an astronomer named Vera Rubin was making some observations on Andromeda to check astronomers assumptions about the orbital speeds of stars, she found something out that was very strange: the outer edges of the galaxy were spinning extremely fast. In fact, they were ...