After almost a century of speculation, proposals and searches for dark matter, physicists now know that it currently comprises about 27% of the universe’s mass-energy, with an abundance over five times that of ordinary matter like you, oceans and exoplanets.

Most of the matter in the universe is dark. On large scales, it is cold and doesn’t collide with anything we recognize, and so, it is called “cold dark matter.” Many candidates have been proposed that could explain the large scale structure of the universe, but none has been established by experiments.