Dark matter

1. In astronomy and cosmology, dark matter is a currently unknown type of matter hypothesized to account for a large part of the total mass in the universe. Dark matter neither emits nor absorbs light or other electromagnetic radiation, and so cannot be directly seen with telescopes. 
2. Dark matter is estimated to constitute 83% of the matter in the universe and 23% of the mass-energy.
3. Dark matter's existence is inferred from gravitational effects on visible matter and gravitational lensing of background radiation, and was originally hypothesized to account for discrepancies between calculations of the mass of galaxies, clusters of galaxies and the entire universe made through dynamical and general relativistic means, and calculations based on the mass of the visible "luminous" matter these objects contain: stars and the gas and dust of the interstellar and intergalactic medium. 
4. The most widely accepted explanation for these phenomena is that dark matter exists and that it is most likely composed of heavy particles that interact only through gravity and possibly the weak force; however, alternate explanations have been proposed, and there is not yet sufficient experimental evidence to determine which is correct.
5. Many experiments to detect proposed dark matter particles through non-gravitational means are underway.
6. The fundamental particles of dark matter are made up of photons moving like like electrons in an atom and their electromagnetic converts other photon to dark matter .