Percent of the universe consisting of unknown components. 23 percent is thought to be made up of poorly understood dark matter, detectable only by its gravitational pull on other material, and 73 percent is dark energy, a completely enigmatic entity that seems to play a role in the accelerating expansion of the universe. Ordinary matter, which makes up the atoms of familiar objects as well as stars and the visible portions of galaxies, sccounts for Just 4 percont of the cosmos.
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