DARK MATTER THEORY

Dark matter theory proposes that there is a type of matter in the universe that does not interact with light or other forms of electromagnetic radiation, but still exerts a gravitational force.

The existence of dark matter was first proposed in the 1930s to explain the observed behaviour of galaxies and galaxy clusters, which did not seem to match up with the amount of visible matter in these systems.

One of the key pieces of evidence for dark matter is the observed rotation of galaxies. According to the laws of gravity, the stars at the outer edges of a galaxy should be moving more slowly than those closer to the center.

However, observations have shown that these outer stars are moving at similar speeds to those closer in, which suggests the presence of additional matter that is not visible. This extra matter has been dubbed "dark matter" because it does not emit or absorb light.

While the exact nature of dark matter is still a mystery, scientists have proposed a number of possible candidates for the dark matter particle. One leading contender is the WIMP (Weakly Interacting Massive Particle), axions, sterile neutrinos, and other exotic particles.

Dark matter is thought to make up about 85% of the matter in the universe. While we cannot directly observe dark matter, its presence can be inferred from its gravitational effects on visible matter.