Dark matter is one of the most intriguing mysteries in modern science. Despite making up approximately 27% of the universe, it cannot be seen or detected directly using traditional instruments. The name "dark matter" itself stems from the fact that it does not emit, absorb, or reflect light, making it invisible to the electromagnetic spectrum. However, its existence is inferred from its gravitational effects on visible matter, such as galaxies, stars, and other celestial objects. Without dark matter, the motion of galaxies would not make sense, as they appear to be moving far too quickly for the amount of visible matter they contain. This unseen substance holds galaxies together and ensures the stability of the universe's large-scale structure.
The story of dark matter begins in the 1930s with the work of Swiss astronomer Fritz Zwicky. While studying the Coma galaxy cluster, Zwicky found that the visible matter in the galaxies was not enough to account for the way the galaxies were moving. He proposed that there must be some form of unseen mass providing additional gravitational pull, which he called "dark matter." Although his hypothesis was met with skepticism, it laid the foundation for further research into this invisible force.
Over the following decades, scientists gathered more indirect evidence supporting the existence of dark matter. In the 1970s, astronomer Vera Rubin and her colleague Kent Ford observed the rotation of galaxies and found that stars on the outer edges were moving much faster than expected. Based on the laws of physics and the visible mass, these stars should have been moving more slowly and would have been flung out of their orbits. The only explanation for their high speed was the presence of a significant amount of unseen mass—dark matter.
