What is dark matter?

Dark matter emits no light, and cannot be directly observed, but scientists think that it and dark energy make up most of the mass of the universe. read more

Although dark matter makes up most of the matter of the universe, it only makes up about a quarter of the composition. The universe is dominated by dark energy. After the Big Bang, the universe began expanding outward. read more

Dark matter is a theorized form of matter that is believed to account for approximately 80% of the matter in the universe, and about a quarter of its total energy density. The majority of dark matter is thought to be non-baryonic in nature, possibly being composed of some as-yet undiscovered subatomic particles. read more

Dark Energy, Dark Matter In the early 1990s, one thing was fairly certain about the expansion of the universe. It might have enough energy density to stop its expansion and recollapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. read more