what is a black hole?

Answer 1

A black hole is a concentration of mass whose gravitational field is so strong that nothing can escape. Black holes are predicted by general relativity. Under the description provided by general relativity, as an object moves closer to a black hole, the energy required for it to escape continues to increase until it becomes infinite at the event horizon, the surface beyond which escape is impossible. Inside the event horizon, the geometry of spacetime is distorted in a way that makes moving closer to the central singularity inevitable no matter how the infalling object moves.

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 been hypothesised that black holes radiate energy due to quantum mechanical effects known as Hawking radiation

Answer 2

black hole
Cosmic body with gravity (see gravitation) so intense that nothing, not even light, can escape. It is suspected to form in the death and collapse of a star that has retained at least three times the Sun's mass. Stars with less mass evolve into white dwarf stars or neutron stars. Details of a black hole's structure are calculated from Albert Einstein's general theory of relativity: a “singularity” of zero volume and infinite density pulls in all matter and energy that comes within an event horizon, defined by the Schwarzschild radius, around it. Black holes cannot be observed directly because they are small and emit no light. However, their enormous gravitational fields affect nearby matter, which is drawn in and emits X rays as it collides at high speed outside the event horizon. Some black holes may have nonstellar origins. Astronomers speculate that supermassive black holes at the centres of quasars and many galaxies are the source of energetic activity that is observed. Stephen W. Hawking theorized the creation of numerous tiny black holes, possibly no more massive than an asteroid, during the big bang. These primordial “mini black holes” lose mass over time and disappear as a result of Hawking radiation. Although black holes remain theoretical, the case for their existence is supported by many observations of phenomena that match their predicted effects.

Answer 3

Black holes are the evolutionary endpoints of stars at least 10 to 15 times as massive as the Sun. If a star that massive or larger undergoes a supernova explosion, it may leave behind a fairly massive burned out stellar remnant. With no outward forces to oppose gravitational forces, the remnant will collapse in on itself. The star eventually collapses to the point of zero volume and infinite density, creating what is known as a " singularity ". As the density increases, the path of light rays emitted from the star are bent and eventually wrapped irrevocably around the star. Any emitted photons are trapped into an orbit by the intense gravitational field; they will never leave it. Because no light escapes after the star reaches this infinite density, it is called a black hole.

Answer 4

When the star is 1.4 times the mass of the sun it does not become a red gaint,instead it becoms a neutron star.
The nucleus of the neutron star the compresses infinetly to become a black hole.
The compressed nucleus is called a black hole because the gravitational pull of a black hole is so high so that light cannot escape from it,hence it is not visible so it called a black hole.

Answer 5

A black hole is an extremely low pressure system that has been created by the passing of a particle into a remnant of the vacuum.

As with all low pressure systems, the surrounding higher pressure system, in this case space, will attempt to make it equal to itself. Depending upon the availability and proximity of matter, this will happen very quickly or very slowly.

If there is very little matter in proximity, it will happen very slowly and the black hole will simply become more space.

If there is a large amount of matter in proximity, it will happen very quickly and the matter will compress itself so much that it becomes an extremely high pressure system and violently explodes as it attempts to equalize the lower pressure system that is now space resulting in basic particles and more remnants of the vacuum to be scattered about and more black holes to be created.

If there is a reasonable amount of matter in proximity, the matter will equalize the low pressure system at a reasonable rate that results in a reasonable amount of compression that results in a reasonable explosion that leaves enough matter intact to create stars, planets and moons which have gravity as a result of their compression and attract each other into orbits and attract spurious elements left floating around which possibly results in an atmosphere which possibly results in life.

Answer 6

Hi there...

Usually huge stars (many times bigger than sun) die and become a "Black Hole".
The size of the star decreases so much that it is just the size of a pin and so its density is enomorous.
It has huge gravitational force which doesnot allow anything to escape...not even light...and thats why we can't see a black hole

The only indication of black hole is a star revolving around an empty space...

Answer 7

Black holes are a series of multiple dimensions that have an extreme amount of gravity. Black holes are also known as worm holes.

Answer 8

u think abt black hole as a very big star.such a star which has escaped it's death.this star has such a large amount of gravitational force that it can even swallow it's own emitted light.this star is applying so much of pressure at one single point that it has penetrated through the space- time (consider it as a sheet)any thing which goes inside it or is sucked by it reaches the end point whichh is actually the starting of time.

Answer 9

A hole that is painted black

Answer 10

It is a region of space resulting from the collapse of a star having an extremely high gravitational field.