A Curious Observation↵
The existence of invisible matter in the universe was first suggested by Dutch astronomer Jan Hendrik Oort in 1932 when he observed that the stars at the outer edge of the galaxy were moving much faster than they should be given the weak gravitational pull at the ends of galaxies. Oort believed that their speed was being influenced by a material with intense gravitational force, which he called 'dark matter' because it could not be seen, Substantiating this discovery a year later was Swiss astronomer Fritz Zwicky who, after a similar observation, maintained that hidden masses lay among invisible ones. However, neither claim was accepted by the scientific community because it was unheard of for a substance with mass to be invisible.↵
An Invisible Web↵
By the 1950s, technology had progressed enough to confirm that outlying stars actually have the same velocity as the stars at the center of a galaxy. Scientists surmised that galaxies must contain significant amounts of dark matter for this to be possible, so they set about learning as much as they could about the elusive material. Aided by computer-generated models, they speculated that flaments of dark matter comprising up to 85 per cent of the universe's total mass formed a web and that woven into this web was all the visible matter of the universe. Some have compared dark matter to connective tissue in that its apparent function is to bind the various components of the universe together. In other words, without it, galaxies would simply break apart and float away.↵
Theories on the Composition of Dark Matter↵
But just what is dark matter made of? Many cosmologists believe that it may be composed of a subatomic particle that has not yet been identified. Meanwhile, some astronomers consider massive compact halo objects, or MACHOs, a possibility. MACHOs are believed to reside in the halos of galaxies but defy detection because of their low luminosities. Other astronomers think that WIMPs, or weakly interacting massive particles, are strong candidates. WIMPs are hypothetical at this point but are a popular choice because scientists believe that they formed shortly after the Big Bang. Being massive, slow-moving, and incapable of emitting light, it is theorised that these particles clumped together to form the structure of the universe. Unsurprisingly, attempts to prove their existence have been determined, and state-of-the-art technologies such as the Large Hadron Collider, are currently being used to try to produce them.↵
Mapping Dark Matter↵
Although there remains a lack of solid evidence, support for the theory of dark matter has grown extensively. It is now the consensus among scientists that it does exist and that, despite its inability to produce light, it can be detected. This is due to the fact that it causes light from galaxies to distort, creating luminous optical illusions. Scientists observing these phenomena measure the displacement of light to determine the approximate location of the dark matter. They then chart these positions on maps. While scientists engaged in the search for dark matter often come up empty-handed, they remain optimistic and driven by discoveries like one made by a team in Munich, Germany in which it was possible to detect and map dark matter in a cluster of galaxies about 2.7 billion light years away.