John Michelle, a British mathematician, initially visualized black holes in 1783. He called them dark stars and his explanation was based on Newton's laws of gravity. Employing Newton's law of gravity, he argued that a suitably thick object would posses an escape speed that is greater than light's speed. John was not sure if such objects exist. He later abandoned his studies on these objects. Polymath Pierre-Simon from France conducted soon afterwards similar research.
In 1915, Albert Einstein introduced his concept of general relativity. This theory enabled the initial good explanations of black holes to be created. One year later Karl Schwarzschild came up with the initial mathematical description. Currently it is referred as Schwarzschild black hole. It explains a black hole that is completely spherical and does not rotate.
Karl Schwarzschild is recognized as a bright astronomer who discovered black holes concept. In 1916, Karl applied Einstein's general relativity's theory. He started by making calculations about the star's gravity fields. Schwarzschild concluded that if a very big object, such as a star, were to be viewed as a minute point, the impacts of Einstein's relativity would be fairly great. Schwarzschild was not sure if a star could be such small. He imagined that in case a star shrinks on itself, its gravity would not change and the planets that are revolving around the star would remain in their orbits.
In 1968, the physicist John Wheeler invented the name black hole. He was one of the most powerful scientists in the black holes research, contributing a huge amount of study to our current understanding of black holes.