What is black hole?

Answer 1

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Answer 2

A black hole is an object predicted by general relativity[1] with a gravitational field so powerful that even electromagnetic radiation cannot escape its pull.[2]

A black hole is defined to be a region of space-time where escape to the outside universe is impossible. The boundary of this region is a surface called the event horizon. This surface is not a physically tangible one, but merely a figurative concept of an imaginary boundary. It is defined as the point near the black hole where escape velocity exceeds the speed of light. Nothing can move from inside the event horizon to the outside, even briefly.

Theoretically, a black hole can be any size. Astrophysicists expect to find black holes with masses ranging between roughly the mass of the Sun ("stellar-mass" black holes) to many millions of times the mass of the Sun (supermassive black holes).

The existence of black holes in the universe is well supported by astronomical observation, particularly from studying X-ray emission from X-ray binaries and active galactic nuclei. It has also been hypothesized that black holes radiate energy due to quantum mechanical effects known as Hawking radiation.

Answer 3

A black hole, a term coined by John Wheeler in 1967, is a region of singularity in space-time, from which nothing can escape - not even light, as the escape velocity at the surface of the black hole (known as the "event horizon") exceeds the speed of light.

Although, Stephen Hawking, the renowned Scientist and author of the bestselling book - "A brief history of Time" suggested that black holes do emit energy - now known as "Hawking Radiation".

Answer 4

A blake hole is formed by a star when its fuel is exhausted. as we in he case of a dying flame , the star expands before it extinquishes . While it expands , it pulls all the galactic matter, like the planets and other objects around it . This accretion of additional matter to an enormous extend , increases the gravity of the mass of the star so much that all he mater including those that the star sucked in collpses into itself and the density of the star increases immensely . The infinite densityof the star is so very powerful that it pulls een the astest moving light itself into itself .so light does not escape the surface of the star . Because of this situation , the star becomes invisible .Though invisible , the star has a nuclear reaction of fusion inside . since the star sucked in all the galactic mater and becomes invisible by pulling evn light , it is clled a black hole .It is not a hole in the sky.

Answer 5

It is a theoretical concept. Were a person to determine mass acceleration within our own sun, they would find that 400 miles outward from its center mass inside that location would all be accelerating atomically to a speed greater than that of the speed of light. Matter cannot exist in this state. Were "black holes" to exist one would have formed within our own sun, for gravitational energy in that location becomes a time distorting, mass sucking monster - which concept defines a black hole.
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Answer 6

A black hole is a quantum singularity. It is formed when the forces of a massive star can no longer support its mass, thus causing it to collapse upon itself. Hence, a great amount of matter in a very compressed point of intense gravitational pull.

Answer 7

A black hole in the universe absorbs all matter and light around its field of effect. May be they are source of mini-crunches leading to Big-crunch.

Answer 8

a black hole is formed when a star dies.it is so powerfully magnetic that even light cannot escape its grip.that is why all the light is absorbed into the centre and the surrounding areas dont have light.

Answer 9

A collapsed star.