This is the biggest unsolved mystery of the universe

Dark matter is a mysterious substance that cannot be seen or measured but has a gravitational effect on visible matter. It makes up about 85% of the universe’s mass, yet its composition and formation remain unknown. Various observations, such as the rotation curves of galaxies, support the existence of dark matter. Possible candidates for dark matter include weakly interacting massive particles, axions, and primordial black holes. However, none of these theories have been confirmed. The search for dark matter is an active area of research that could unveil new insights into the nature of reality.