Dark matter is a hypothetical form of matter that is thought to make up a significant portion of the total mass in the universe. It is called "dark" because it does not interact with electromagnetic radiation (such as light) in a way that allows us to directly observe or detect it using traditional astronomical methods.
The existence of dark matter is inferred from its gravitational effects on visible matter and the large-scale structure of the universe. It was proposed to explain certain astronomical observations that could not be accounted for by the known forms of matter, such as stars, gas, and dust.
The nature of dark matter is still unknown. It does not emit, absorb, or reflect light, which is why it cannot be directly observed using telescopes that rely on detecting light. It also does not interact strongly with electromagnetic forces, making it difficult to detect through traditional means.
Various hypotheses have been put forward to explain the nature of dark matter. One leading theory suggests that dark matter consists of particles that do not interact with light or other electromagnetic radiation, but still interact gravitationally with other matter. These hypothetical particles are collectively referred to as Weakly Interacting Massive Particles (WIMPs). However, despite extensive experimental efforts, no definitive direct detection of dark matter particles has been made to date.
Alternative theories propose different possibilities, such as primordial black holes, modified theories of gravity, or other exotic particles. However, the true nature of dark matter remains a mystery and an active area of research in astrophysics and particle physics.