Thought to be the answer to Zwicky's missing mass problem, for 10 points, name this class of substances that does not emit radiation, rendering them invisible in the galaxy.
Scientists can use weak gravitational lensing to find out the statistical distribution of this material. It can be separated into two classes: baryonic and nonbaryonic; the latter of is further subdivided into (*) warm, hot, and cold divisions. Candidates for material include Massive Compact Halo Objects and Weakly Interacting Mass Particles, or MACHOs and WIMPs respectively. It constitutes almost a quarter of the total mass-energy of the universe. Thought to be the answer to Zwicky's missing mass problem, for 10 points, name this class of substances that does not emit radiation, rendering them invisible in the galaxy.
Scientists can use weak gravitational lensing to find out the statistical distribution of this material.
{dark matter}