Who was the first person to discover a black hole?
A common type of black hole is produced by certain dying stars. A star with a mass greater than about 20 times the mass of our Sun may produce a black hole at the end of its life. In the normal life of a star there is a constant tug of war between gravity pulling in and pressure pushing out. Nuclear reactions in the core of the star produce enough energy and pressure to push outward. For most of a star’s life, gravity and pressure balance each other exactly, and so the star is stable. However, when a star runs out of nuclear fuel, gravity gets the upper hand and the material in the core is compressed even further. The more massive the core of the star, the greater the force of gravity that compresses the material, collapsing it under its own weight.
Karl Schwarzschild is credited with being the brilliant astronomer who developed the concept of black holes. In 1916, using Einstein’s general theory of relativity, he began to make calculations about the gravity fields of stars. He concluded that if a huge mass, such as a star, were to be concentrated down to the size of an infintessimal point, the effects of Einstein’s relativity would get really fairly extreme. Schwarzschild doubted that a star could get that small, and theorized that if a star did infact shrink upon itself like that, its gravity would remain the same and the planets revolving around it would remain in the same orbits they always had. Since then however, some of Schwarzschild’s theories have been disproved, but most of his initial theories hold intact today.