Dark matter

Dark matter is a form of matter called dark because it does not appear to interact with the electromagnetic field, which means it doesn't absorb, reflect or emit electromagnetic radiation.

About 69 percent of the matter/energy (since matter and energy are interchangeable) in the universe is contained in dark energy. Dark matter makes up about 26 percent, atoms of hydrogen and helium make up about 5 percent, and higher elements, which make up the Earth and our own bodies, only make up a tiny 0.5 percent. So dark energy, which is pushing the galaxies away from us, is clearly the dominant force in the universe, much larger than the energy contained in the curvature of spacetime.

Current thought is that most of the dark matter probably does not consist of the standard elementary particles—such as protons, neutrons, electrons and known neutrinos—but rather hypothetical and exotic constituents such as sterile neutrinos, axions, and WIMPs (Weakly Interacting Massive Particles, including neutralinos), which do not interact with electromagnetism and thus cannot be easily detected. The hypothetical neutralinos are similar to neutrinos, but heavier and slower. Theorists also consider the wild possibility that dark matter includes gravitons, hypothetical particles that transmit gravity, leaking into our universe from neighboring universes. If our universe is on a membrane “floating” within a higher dimensional space, dark matter may be explained by ordinary stars and galaxies on nearby membrane sheets.

Type I civilizations find it to comprise of particles not hitherto detected in previous standard and therefore limited models of particle physics. Once discovered, the term "dark matter" was regarded in the same way as aether which was once thought to comprise most of the observable universe beyond earth.

See also:

Dark energy