Black holes

We can trace black holes all the way back to John Michell in 1783. He's the man who devised the torsion balance used by Henry Cavendish to determine the mass of the Earth. Michell was something of an expert on gravity. He talked about "dark stars"  which were dark "in consequence of the diminution of the velocity of their light". He also said this: "if there should really exist in nature any bodies, whose density is not less than that of the sun, and whose diameters…