A black hole is a region where gravity is so strong that even particles or electromagnetic radiation, such as light, cannot escape. The general theory of relativity predicts that space-time will be distorted to form a black hole of sufficiently compact mass.
The boundary of the inaccessible area is called the event horizon. Although the event horizon greatly influences the fate and circumstances of an object's transcendence, it has no locally identifiable features in terms of general relativity. In many ways, a black hole acts like a suitable black hole because it does not reflect light. Moreover, the quantum field theory of curved spacetime predicts that event horizons emit Hawking radiation, the same spectrum of a black body with its mass inversely proportional to its mass. This temperature is in the order of billions of kelv to the black holes of the star mass, making it impossible to observe.
Gravitational fields were first considered by John Michel and Pierre-Simon Laplace in the 18th century. In 1916, Karl Schwarzschild discovered the first modern solution to the general relativity of black holes. In 1958, David Finkelstein first published his commentary on an area where nothing could escape. Black holes were considered a mathematical curiosity; Until the 1960s, theoretical works showed a general prediction of general relativity. The discovery of neutron stars by Jocelyn Bell Burnell in 1967 led to an interest in gravitationally compact objects that became an astronomical reality.
When very large stars collapse at the end of their life cycle, black holes are expected to form. Once a black hole is formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging them with other black holes, massive black holes of millions of solar masses can be formed. Most galaxy centers are thought to have supermassive black holes.
The presence of a black hole can be inferred from interactions with other objects and from electromagnetic radiation, such as visible light. Matter falling into a black hole can form an external accretion disk heated by friction and form quasars, the brightest objects in the universe. Stars passing very close to a supermassive black hole can be transformed into very bright glowing streamers before being "swallowed". If there are other stars orbiting a black hole, their orbits can be used to determine the mass and position of the black hole. Such observations can be used to avoid possible alternatives, such as neutron stars. In this way, astronomers have identified several stellar black hole candidates in binary systems,
On February 11, 2016, LIGO Scientific Cooperation and Virgin Cooperation announced the direct detection of gravitational waves, which also represents the first observation of a black hole merger. As of December 2018, eleven gravitational waves have been observed to have originated from ten black holes (along with a binary neutron star fusion). On April 10, 2019, the first live image of the black hole and its surroundings was published, following observations made by the 2017 event Horizon Telescope of the supermassive black hole at Messier 87's Galactic Center.
In a letter published in November 1784, John Michel, an astronomical pioneer and English priest, suggested the idea of a body so gigantic that even light could not escape. Michelle's simple calculations assume that such a body has the same density as the Sun. When the diameter of a star exceeds the Sun's factor of 500, the speed at which it escapes from the surface exceeds the normal speed of light. Michelle rightly noted that such supermassive but non-radioactive objects can be detected by the effects of gravity on nearby visible bodies. Scholars of the time were initially enthusiastic about the idea that giant but invisible stars might be hidden from view.
If light were more of a wave than a "corpuscle", it is not clear what effect gravity would have on escaping light waves. Modern physics slows down Michelle's idea of shooting a ray of light directly from the surface of a supermassive star.
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