what is a blackhole?

Answer 1

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Answer 2

A blackhole is a that thing tat has great gravitational force that not even light can escape it, usually as what scientists say, when you enter a blackhole your molecules something like breaks apart, like the nuclear force isnt present inside a black hole and other scientist say that its similar to a worm hole, which is a shortcut to a really far place, like most probably Milky Way has a worm hole to Andromeda and when you pass that worm hole you only take up 10000 light years but if you travel the longer way, from the Milky Way itself then it may take like a bilion light years or something

Answer 3

Blackhole is the last stage in the life of a star...the gravity in a blackhole will be so high that even light gets trapped in it...

Answer 4

A black hole is a (hypothetical) 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.

Answer 5

A black hole is a (hypothetical) 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 also been hypothesised that black holes radiate energy due to quantum mechanical effects known as Hawking radiation.

Answer 6

Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. Since our best theory of gravity at the moment is Einstein's general theory of relativity, we have to delve into some results of this theory to understand black holes in detail, but let's start of slow, by thinking about gravity under fairly simple circumstances

There is no limit in principle to how much or how little mass a black hole can have. Any amount of mass at all can in principle be made to form a black hole if you compress it to a high enough density. We suspect that most of the black holes that are actually out there were produced in the deaths of massive stars, and so we expect those black holes to weigh about as much as a massive star. A typical mass for such a stellar black hole would be about 10 times the mass of the Sun,
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Answer 7

a blackhole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.the gravitational field is so strong that escape velocity near it exceeds the speed of light.

Answer 8

A star that has passed the red star expansion phase and collapsed in on itself. It coalesces into a super dense ball of matter where a spoonfull could weigh as much as planets and it exerts tremendous gravitational pull such that even light cannot escape, thereby rendering it invisible. You gauge the existence of a black hole by the effect it has on nearby matter/ objects.

Answer 9

What is a black hole?

A black hole is an object that is so compact (in other words, has enough mass in a small enough volume) that its gravitational force is strong enough to prevent light or anything else from escaping.

The existence of black holes was first proposed in the 18th century, based on the known laws of gravity. The more massive an object, or the smaller its size, the larger the gravitational force felt on its surface. John Michell and Pierre-Simon Laplace both independently argued that if an object were either extremely massive or extremely small, it might not be possible at all to escape its gravity. Even light could be forever captured.

The name "black hole" was introduced by John Archibald Wheeler in 1967. It stuck, and has even become a common term for any type of mysterious bottomless pit. Physicists and mathematicians have found that space and time near black holes have many unusual properties. Because of this, black holes have become a favorite topic for science fiction writers. However, black holes are not fiction. They form whenever massive but otherwise normal stars die. We cannot see black holes, but we can detect material falling into black holes and being attracted by black holes. In this way, astronomers have identified and measured the mass of many black holes in the Universe through careful observations of the sky. We now know that our Universe is quite literally filled with billions of black holes.

How big is a black hole?

All matter in a black hole is squeezed into a region of infinitely small volume, called the central singularity. The event horizon is an imaginary sphere that measures how close to the singularity you can safely get. Once you have passed the event horizon, it becomes impossible to escape: you will be drawn in by the black hole's gravitational pull and squashed into the singularity.

The size of the event horizon (called the Schwarzschild radius, after the German physicist who discovered it while fighting in the first World War) is proportional to the mass of the black hole. Astronomers have found black holes with event horizons ranging from 6 miles to the size of our solar system. But in principle, black holes can exist with even smaller or larger horizons. By comparison, the Schwarzschild radius of the Earth is about the size of a marble. This is how much you would have to compress the Earth to turn it into a black hole. A black hole doesn't have to be very massive, but it does need to be very compact!

Some black holes spin around an axis, and their situation is more complicated. The surrounding space is then dragged around, creating a cosmic whirlpool. The singularity is an infinitely thin ring instead of a point. The event horizon is composed of two, instead of one, imaginary spheres. And there is a region called the ergosphere, bounded by the static limit, where you are forced to rotate in the same sense as the black hole although you can still escape.

How are black holes born?

A black hole is born when an object becomes unable to withstand the compressing force of its own gravity. Many objects (including our Earth and Sun) will never become black holes. Their gravity is not sufficient to overpower the atomic and nuclear forces of their interiors, which resist compression. But in more massive objects, gravity ultimately wins.

Stellar-mass black holes are born with a bang. They form when a very massive star (at least 25 times heavier than our Sun) runs out of nuclear fuel. The star then explodes as a supernova. What remains is a black hole, usually only a few times heavier than our Sun since the explosion has blown much of the stellar material away.

We know less about the birth of supermassive black holes, which are much heavier than stellar-mass black holes and live in the centers of galaxies. One possibility is that supernova explosions of massive stars in the early Universe formed stellar-mass black holes that, over billions of years, grew supermassive. A single stellar-mass black hole can grow rapidly by consuming nearby stars and gas, often in plentiful supply near the galaxy center. The black hole may also grow through mergers with other black holes that drift to the galactic center during collisions with other galaxies. Astronomers are actively investigating these and other scenarios through observations and computer simulations.

Answer 10

To make it simple and clear to all , without much of scientific knowledge , the black hole refers to one of the stages in the life cycle of a star..it is the final stage that he star reaches on exhaustion of the fuel that is burning in it. All the materthat is burning in a star is converted into gaseous material and the expand in volume immensely. juust as thedying flame of a n oil lamp that swells befroe it dies out . You know that the bodies of big mass have a force of attraction and the expanded star exerts an immense force of attraction on all that galactic matter around it and pulling them into itself while collopsing due to the exhaustiion (conversion ) of its fuel. even while burning nothing like smoke or the gasescould escape and get out of the atmospher of the star because of its gravitational pull. when tall the galactic matter around the star also get pulled inside they fall into the star like the the water falling into the swirling eddy forming in a river in floods and fallinto the star which grows in mass and acquires an enormous force of gravity wiithhigh intensity that even light is pulled inside and is unable to escpe from the collopsing star . since light does not escape fromthe star , the star becomes invisible and so it is known as a black hole . because of the intense nuclear reaction thereseems to be some radiation by which the presence of the star in located. The star as a black hole is in a stage of re-creation and will again develop into a star or may set off a big Bang to create a new steelar system. This should prove that matter is indestructible and that it can only changed from one to anotheer and that nature is capable of recycling everything incessantly. The universe and all th matter in it will never cease to exist , but will be continuing to change from one to another .The processe of change may take millions and billions of years ; but will never cease to exist . Nothing woud destroy the Universe .and nothing could stop the changes too. Wonderful universe and undying universe.

Answer 11

another definition of BLACKHOLE

Blackhole is a C program designed to stop spam and prevent unwanted senders from sending you email. It is put in the .qmail file and will divert spam and viruses to separate files which can be checked with an IMAP client if configured to do so.

http://sourceforge.net/projects/blackholespam/

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http://www.wisegeek.com/what-is-a-black-hole.htm

In its simplest sense, a black hole is an area of space wherein there is no way for an object to escape its gravitational pull. Do black holes exist? Astronomers certainly believe they do, though confirmation of black holes can not currently be made by direct evidence. Items contained in a black hole will remain there for an infinite period of time.