The Universe

The universe


Black holes
* is a region of space-time caused by a large concentration of mass inside, with huge increases in density, which generates a gravitational field such thatno particle of matter, even photons of light, can escape from that region.

History black holes
* The concept of a body so dense that even light could escape it, was described in a paper submitted in1783 to the Royal Society called for an English geologist John Michell. At that time Newton's theory of gravitation and the concept of escape velocity were well known. Michell calculated that a body with aradius 500 times that of the sun and the same density, would, on its surface, an escape velocity equal to that of light and would be invisible. In 1796, the French mathematicianPierre-Simon Laplace explained in the first two editions of his book Exposition duSysteme du Monde the same idea though, to gain the idea that light was a wave with no mass in the nineteenth century was ruled in latereditions.

Albert Einstein
* In 1915, Einstein developed general relativity and showed that light was influenced by the gravitational interaction. A few months later, Karl Schwarzschild found asolution to Einstein's equations, where a heavy body would absorb the light. It is now known that the Schwarzschild radius is the radius of the event horizon of a black hole that does not rotate, but thiswas not well understood at the time. Schwarzschild himself thought it was just a mathematical solution, not physical.
* Other notes.
Objects whose gravity field is too strong for light to escapewere first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by KarlSchwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was not fully appreciated for another four decades. Long considered a mathematical curiosity, it was...