```
```

### Timeline of black hole physics

* 1640 - Ismael Bullialdus suggests an inverse-square gravitational force law * 1684 - Isaac Newton writes down his inverse-square Law of universal gravitation, * 1758 - Ru?er Josip Bo?kovi? developes his Theory of forces, where gravity can be repulsive on small distances. So according to him such strange classical bodies, similar to white holes, can exist, which won't let other bodies to reach their surfaces, * 1784 - John Michell discusses classical bodies which have escape velocities greater than the speed of light, * 1795 - Pierre Laplace discusses classical bodies which have escape velocities greater than the speed of light, * 1798 - Henry Cavendish measures the gravitational constant G, * 1876 - William Clifford suggests that the motion of matter may be due to changes in the geometry of space, * 1909 - Albert Einstein together with Marcel Grossmann starts to develop a theory which would bind metric tensor gik, which defines a space geometry, with a source of gravity, that is with mass, * 1910 - Hans Reissner and Gunnar Nordstršm defines Reissner-Nordstršm singularity, Hermann Weyl solves special case for a point-body source, * 1916 - Karl Schwarzschild solves the Einstein vacuum field equations for uncharged spherically-symmetric non-rotating systems, * 1917 - Paul Ehrenfest gives conditional principle a three dimensional space, * 1918 - Hans Reissner and Gunnar Nordstršm solve the Einstein-Maxwell field equations for charged spherically-symmetric non-rotating systems, * 1918 - Friedrich Kottler gets Schwarzschild solution without Einstein vacuum field equations, * 1923 - George Birkhoff proves that the Schwarzschild spacetime geometry is the unique spherically symmetric solution of the Einstein vacuum field equations, * 1939 - Robert Oppenheimer and Hartland Snyder calculate the gravitational collapse of a pressure-free homogeneous fluid sphere and find that it cuts itself off from communication with the rest of the Universe, * 1963 - Roy Kerr solves the Einstein vacuum field equations for uncharged symmetric rotating systems, * 1964 - Roger Penrose proves that an imploding star will necessarily produce a singularity once it has formed an event horizon, * 1965 - Ezra Newman, E. Couch, K. Chinnapared, A. Exton, A. Prakash, and Robert Torrence solve the Einstein-Maxwell field equations for charged rotating systems, * 1967 - Werner Israel presented the proof of the no hair theorem at Kings College in London, * 1968 - Brandon Carter uses Hamilton-Jacobi theory to derive first-order equations of motion for a charged particle moving in the external fields of a Kerr-Newman black hole, * 1969 - Roger Penrose discusses the Penrose process for the extraction of the spin energy from a Kerr black hole, * 1969 - Roger Penrose proposes the cosmic censorship hypothesis, * 1971 - Identification of Cygnus X-1/HDE 226868 as a binary black hole candidate system, * 1972 - Stephen Hawking proves that the area of a classical black hole's event horizon cannot decrease, * 1972 - James Bardeen, Brandon Carter, and Stephen Hawking propose four laws of black hole mechanics in analogy with the laws of thermodynamics, * 1972 - Jacob Bekenstein suggests that black holes have an entropy proportional to their surface area due to information loss effects, * 1974 - Stephen Hawking applies quantum field theory to black hole spacetimes and shows that black holes will radiate particles with a blackbody spectrum which can cause black hole evaporation, * 1989 - Identification of GS2023+338/V404 Cygni as a binary black hole candidate system, * 2002 - Astronomers present evidence for the hypothesis that Sagittarius A* is a supermassive black hole at the centre of the Milky Way galaxy, * 2002 - NASA's Chandra X-ray Observatory identifies double galactic black holes system in merging galaxies NGC 6240.