**Black hole**(black hole or black hole) is a region of

**no time**that the gravitational field prevents everything, including light, from escaping. General relativity predicts that a large enough amount of matter in a small enough range will warp spacetime to become a black hole. Surrounding the black hole is a surface defined by a mathematical equation called the event horizon, at which matter passing through it will not be able to escape from the black hole. A black hole is called “black” because it absorbs all radiation and matter that passes through the event horizon, like an absolute black body in thermodynamics; it is also not some kind of “hole” or “hole” but a region of space-time that does not let anything out. Quantum field theory in curved spacetime predicts that at the event horizon a black hole will emit radiation just as a black body of a certain temperature emits thermal radiation. This temperature is inversely proportional to the mass of the black hole, which makes it very difficult to observe this radiation for medium or stellar mass black holes.

In the 18th century, John Michell and Pierre-Simon Laplace considered an object whose strong gravitational field described by classical mechanics prevented light from escaping. The first modern theory of the nature of black holes was given by Karl Schwarzschild in 1916 when he found the first exact solution to Einstein’s field equation, despite the physical significance and interpretation of the space-region. time without what can be escaped being first proposed by David. Finkelstein in 1958. For a long time, physicists considered Schwarzschild’s solution to be a purely mathematical description. It wasn’t until the 1960s that new theoretical studies showed that black holes formed according to the strict predictions of general relativity. When astronomers discovered neutron stars, pulsars and Cygnus X-1 – a black hole in a binary star system, predictions of gravitational collapse came true, and the concept of a black hole with a system of binary stars has come true. into theories describing these special entities in the universe.

###### *Illustration of a black hole several times the mass of the Sun and its companion star approaching so close that the distance between them is less than the Roche limit. Material from the nearby star is sucked into the black hole, creating an accretion disk. Radiation and high-energy particles are emitted at the poles by the black hole’s rotation and magnetic field.*

Although it is by definition completely black or invisible, the existence of a black hole can be inferred from its interaction with surrounding matter and radiation such as light. Matter falling into the black hole forms in an accretion zone, where matter collides and rubs against each other, becoming a plasma state that emits intense radiation; making the environment surrounding the black hole one of the brightest objects in the universe. If there is a star orbiting a black hole, its shape and orbital period allow astronomers to determine the black hole’s mass and distance. This data allows them to distinguish whether a dense object is a black hole or a neutron star… In this way, many black holes have been discovered in binary star systems, and in the center of the Milky Way is a hole giant black. with a mass about 4.3 million times that of the Sun.

The theory of a black hole, where a strong gravitational field is concentrated in a small region of spacetime, is one of the theories that require the synthesis of general relativity describing gravity with the standard model of mechanics quantum. And today, theorists are still building a theory of quantum gravity capable of describing the singularity at the center of a black hole.

The first directly measured gravitational wave event announced by the LIGO team on February 11, 2016 also directly demonstrated the existence of a system of two stellar-mass black holes that orbited each other and eventually merged to form a more massive rotating black hole.

*The image simulates the black hole as it bends spacetime around it, revealing multiple images of the same star as well as Einstein’s ring.*

Refer to WIKIPEDIA

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