What is the blackhole?

Answer 1

A black hole is an object predicted by general relativity, with a gravitational field so powerful that even electromagnetic radiation (such as light) cannot escape its pull.

A black hole is defined to be a region of space-time where escape to the outside universe is impossible. The outer boundary of this region is called the event horizon. Nothing can move from inside the event horizon to the outside, even briefly, due to the extreme gravitational field existing within the region. For the same reason, observers outside the event horizon cannot see any events which may be happening within the event horizon; thus any energy being radiated or events happening within the region are forever unable to be seen or detected from outside. Within the black hole is a singularity, an anomalous place where matter is compressed to the degree that the known laws of physics no longer apply to it.

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 an undetectably small amount of energy due to quantum mechanical effects. This is called Hawking radiation.

Most planets and other celestial bodies are stable because the Pauli force between electrons prevents atoms from collapsing into each other, while gravity, electromagnetism, and the strong force pull them together. These create a balance which allows material bodies to retain their shape and structure. In extreme circumstances, however, if there is enough matter in a small enough space, gravity ends up winning, and the matter collapses: electrons cannot stay distant from the atomic nucleus, and incredibly dense matter forms (sometimes called neutronium). Eventually, if the star is massive enough, even the Pauli force between nucleons cannot resist gravity and the star collapses into itself further forming a black hole. In a way that can be hard to imagine, nothing can stop this collapse if enough matter gets into a small enough space, and the matter collapses to a point of zero height, width, and depth, known as a singularity, in which the matter is so dense it is no longer "matter" in any real sense, but some kind of anomaly in space. Anything that gets too close to this singularity will also collapse into it the same way, whether it is matter, energy or even light itself, which is the fastest thing in the universe. The failure of even light to escape its gravitation is how the phenomenon initially acquired the name black hole.

Because matter and energy which passes this "boundary" can never escape back again, observers outside this invisible "boundary" can neither see inside nor detect what might happen within the interior - it is forever unable to be witnessed. The invisible 'dividing line' in space where matter or energy will be unavoidably drawn into the black hole is known as the event horizon, because like the earth's horizon nothing can be seen beyond it.

It was later found that energy can escape from black holes in an unexpected way, and that therefore black holes can evaporate. In space, virtual particles are continually coming into existence and vanishing on a microscopic scale that is so small they cannot easily be detected. This is a consequence of quantum physics and only works on a subatomic scale. Conceptually, these particles can be imagined to appear in pairs and vanish a tiny fraction of a second later again. For this reason they are not readily noticed. But close to the black hole's event horizon, the intense gravitational field separates the two particles even in the fractional second that they exist. One particle may be absorbed into the black hole, the other escapes. From an external perspective all that is seen is the second of these, giving the appearance of energy being radiated outward, escaping from its gravitational field beyond the event horizon. In this way, paradoxically, black holes can evaporate. This process is thought to be significant for the very smallest black holes, as a black hole of stellar mass or larger would absorb more energy from cosmic microwave background radiation than they lose this way. The radiation emitted is referred to as Hawking radiation.

Black holes generally come in two types: those with a mass up to ten times the mass of our Sun, and those with a mass that is millions or billions of times that of our sun. The latter are called supermassive black holes, and are thought to exist at the centers of galaxies. Micro black holes are believed to be possible but very short-lived, capable of creation under extreme circumstances such as the Big Bang or perhaps by very high powered particle accelerators or ultra-high-energy cosmic rays.

Answer 2

Hello,friend.A star which blasts and disappears in the space makes blackhole.Blackhole is a very dangerous thing.It sucks space-vehicles,sattelites,space-stations etc.In blackhole time stops running and it is too dark that a man cannot see a thing which is standing just beside him.In the year of 1980 a sattelite sent by Russia being sucked by a blackhole and informations came on the space-center's computers where it is sent from-"It is might be a blackhole,all the machines are out of control and here is no light."

Answer 3

A black hole is nothing but a "dead" star. It's force of gravity is so strong that once you enter it there is no coming back. I'll use a little math to make this clear.

There is a particular value of the velocity required to break away from any planets gravitational pull. This velocity is called "escape velocity and is given by the formula: sqrt(2GM/R) here G is a constant and R is th radius of the planet/star. If due to come cause the mass of the planet remains the same and it's size(volume) reduces, or the volume remains same and mass increases so much that:
sqrt(2GM/R) becomes greater tha the speed of light, then it would mean that an object will require a velocity greater than the speed of light to break away from the gravitational pull, but by Einstein's Theory of Relativity no speed can exceed the speed of light so the once the object enters, it can never come out.

Answer 4

A black hole is a region of spacetime from which nothing can escape, even light.

To see why this happens, imagine throwing a tennis ball into the air. The harder you throw the tennis ball, the faster it is travelling when it leaves your hand and the higher the ball will go before turning back. If you throw it hard enough it will never return, the gravitational attraction will not be able to pull it back down. The velocity the ball must have to escape is known as the escape velocity and for the earth is about 7 miles a second.

As a body is crushed into a smaller and smaller volume, the gravitational attraction increases, and hence the escape velocity gets bigger. Things have to be thrown harder and harder to escape. Eventually a point is reached when even light, which travels at 186 thousand miles a second, is not travelling fast enough to escape. At this point, nothing can get out as nothing can travel faster than light. This is a black hole.

Answer 5

A void or a drain in the space.. prof. stephen Hawkings says black holes could be the door to another universe(baby universes)..
It comes into existence when a very large star(100 times the size of sun) burns out all its Hydrogen and Helium in the core and fails to equalize the tremendous forces of gravitation and pressure in its core... It collapses under its own gravity to an extent that it becomes virtually nothing..the enormous mass of the star is compressed in a very small space..(the entire nature of space and time gets modified)
The enormous gravitational force causes the escape velocity to increase to an extent that even light can't escape it..(black holes
can be "identified" by it's effect on other celestial bodies)
The extent of the influence of the black can be found from Chandreshekar's limit formula..
Remember " the bigger they are, the harder they fall"
Read stephan Hawkings works for more insight..

Answer 6

that's obtainable that there are blackholes wandering around between the stars of the Milky way, and that one in each and every of them might collide with the Earth or solar and wreck it. Such activities could be fairly uncommon, although, using fact they are relatively lively and if this form of factor had got here approximately to any of the trillion different stars interior the Milky way interior the previous few a protracted time, we probable might have seen it. all the black holes that we certainly understand approximately (interior the galactic center, Cygnus X-a million) are so distant that any interplay between us and them is hundreds of hundreds of thousands of years interior the destiny, and not going even then.

Answer 7

It is now believed that at the center of each galaxy there is a super-massive black hole that is millions to billions of times heavier than our sun. The massive black hole captures nearby stars and drags them into a swirling accretion disk. A "torus" in the inner accretion shields the black hole in those systems that are viewed edge on (which is probably the case for our galactic center). In many of these systems (which are called AGN = active galactic nucleus), a jet is ejected perpendicular to the disk and is seen in the optical and radio wavebands. In the very central regions the disk becomes so hot (tens of millions of degrees) that the emission is in the X-ray and Gamma-ray bands. This animation shows an artist's impression of the view from an approaching spaceship. The HEASARC data archives contain many observations of these systems made with orbiting X-ray and Gamma-ray observatories.

Answer 8

a black hole is a sun that has collapsed in on itself and is barely 5% of its old size but its mass is great. so great that its gravity does not let even light escape and it can also distort space around it.

imagine taking our sun and crushing it down to the size of a soccer ball yet have all the same matter there but crushed together as tight as it can go. once you do that you have a blackhole.

Answer 9

It's a dead star, very much like the sun, only it's on another galaxy. when a sun is dying, it goes true many steps, then at last it forms a blockhole. It has strong gravity pull so it sucks everything in it. One day our own sun will too!

Answer 10

Black Hole is a high gravity area which is formed after the death of a very huge star. Black Hole rarely forms but when it forms its results are devasting.Black Hole's is very small but its density and gravity is so much higher.Black Hole's gravitational pull is so much high that even light cannot escape from there.Thus its name become black hole.