what do u mean by black hole?what does it contain?
596967
A black hole is a concentration of mass great enough that the force of gravity prevents anything past its event horizon from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). The gravitational field is so strong that the escape velocity past its event horizon exceeds the speed of light. This implies that nothing, not even light, inside the event horizon can escape its gravity. It is, however, theorized that wormholes can let one exit a black hole. The term "black hole" is widespread, even though it does not refer to a hole in the usual sense, but rather a region of space from which nothing can return.\n\nThe 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.
437749
Most astronomers believe that the Milky Way Galaxy -- the galaxy in which our solar system is located -- contains millions of black holes. Scientists have found a number of black holes in the Milky Way. These objects are in binary stars that give off X rays. A binary star is a pair of stars that orbit each other. \n\nhttp://www.nasa.gov/worldbook/blackhole_worldbook.html
711640
Sorry to Sun of Samsa.  I meant to give you a thumbs up!  The Black Hole Singularity is infinitely small (infinite density and ZERO volume).  The effects of the hole can be miles or light years across!
63870
Not much is known about black holes. What is known is only an estimate of how it might work.
417072
Let me ask you something.  Since density is defined as the mass divided by the volume, how did you determine the mass of a black hole to be 10^13 kg/m^3?  Since the volume of a black hole is 0 (a singularity is a 0 dimentional point with no volume), then the mass divided by the volume (0) equals infinity.  Therefore, a black hole has an infinite volume, which is a heck of a lot larger than 10^17kg/m^3.\n\nPS Densiest isn't a word, and even if it were, you'd be spelling it wrong.  Grow a brain before you start talking down to people.
128460
It might be, or it might be a neutron star. We do not really know. \n\nThere are some other objects in the sky which are much more certainly black holes, from their masses and other properties.
396678
first of all, what u consider as dark matter is wrong. dark matter is not some hi-fi stuff which is highly radioactive or has some special properties. its just ordinary matter which cant be seen. secondly to ur question.. the outer limit of a black hole is called schwarzchild radius. when any matter approaches this limit, it cant escape whatsoever. ok, now our matter is in the black hole. first of all, 50% of the mass of the material gets converted into x-rays and other high energy radiation. of the remaining half, some part is used up in the fusion process, while the remaning part is used up in the expansion of the black hole. \nand because black hole is just an ordinary star with extraordinary high density, there is no such thing as a whilte hole. if u meant to say something like blackhole made up of antimatter which attracts matter and mutually anhilates, then may be ur question (2) makes sense.
85056
Search black hole in the internet.
503211
The X-ray source in the constellation Cygnus, aptly named Cygnus X-1, is the best candidate for a black hole that we know of. Most Scientists now agree that it is a black hole. Stephen Hawking won a nobel prize for demonstrating that black holes do not in fact absorb everything that comes near them, as was previously thought, they can and do emit some particles from near their 'event horizons'. This is known as Hawking radiation.
661081
A black hole is a concentration of mass great enough that the force of gravity prevents anything past its event horizon from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). The gravitational field is so strong that the escape velocity past its event horizon exceeds the speed of light. This implies that nothing, not even light, inside the event horizon can escape its gravity. It is, however, theorized that wormholes can provide an exit path for energy or matter. The term "black hole" is widespread, even though it does not refer to a hole in the usual sense, but rather a region of space from which nothing can return.
755373
Black holes are a concept in cosmology and theoretical physics.  The idea of going into one doesn't really fit in with the science. \n\nUsing a mechanical model of the universe, black holes are extremely dense concentrations of matter with such a high gravitational force that everything (including light) is sucked in and cannot escape.  If you went near a black hole, you would be broken down into subatomic particles and crammed into the lump of compressed matter at the centre.\n\nHowever, quantum physics gives an alternative theory.  Black holes could be the ways in and out of shortcuts across the universe so that something sucked into one could be spat out of another.  This is probably something best not tried at home.
790112
A black hole is an object predicted by general relativity with a gravitational field so strong that nothing can escape it — not even light.\n\nA 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 physical, just an imaginary boundary. Nothing can move from inside the event horizon to the outside, even briefly.\n\nThe 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. \n\nHistory\n\nThe concept of a body so massive that even light could not escape was put forward by the English geologist John Michell in a 1784 paper sent to the Royal Society. At that time, the Newtonian theory of gravity and the concept of escape velocity were well known. Michell computed that a body with 500 times the radius of the Sun and of the same density would have, at its surface, an escape velocity equal to the speed of light, and therefore would be invisible. In his words:
21273
I've heard some call black matter a blackhole. The honest truth is we just dont know. Its a theory nothing more. A human concept to TRY to understand something. \n\nLike the notion of "time". We measure that based on our small experiences within our solar system. For all we know there could be a larger, grander universal measurement.
473830
A Black hole is a Quantum Singularity in which so much matter energy, be it solid, liquid, gas, or particle matter evaporated states are attracted to it through the quantum gravitational attraction, and once they enter into the singularity those states are crunched into a quantum compressed state in which matter energy will exist with absolutely no function, and the quantum gravity state is so strong nothing at all, not even light quanta can escape this state so long as it remains stable.\n\nAlso nothing at all can travel through a Black hole it is a supper solid mass, which will crunch any, and everything which enters it, if you here that it is a gateway to another universe, or you can pass through it, the person telling you this is probably watching to many Disney movies.\n\nA worm hole is completely different state of function, and actually folds space with respect to an energy vortex which I believe occurs naturally under specific conditions, and can also be created, however no person has created one to my knowledge at this time, with respect to this time line which we are now living in, and observing, although if they have then I feel positive that it would be labeled top secret, and we would know be the wiser to that knowledge.
554770
A black hole is believed to be a neutron star that collapsed in itself because of extreme gravity. The gravity would get so strong that it forces even time and space into itself including light (that's why it's called black). Also associated with a "wormhole" and figured to be a portal to parallel universes or looped back to this universe in a different time, after the theory of the Einstein-Rosen-Bridge.\nI don't know if someone tried to measure the value of the gravity or if there is even a speculated formula but I don't think so.
1171217
hmmmmm\na chirstian in a black hole wielding a black hole\n\nha ha ha
761120
try this   http://uk.wrs.yahoo.com/_ylt=A0geuljFJktF2mIBr3FLBQx.;_ylu=X3oDMTE5ZTFiZDM5BGNvbG8DZQRsA1dTMQRwb3MDMQRzZWMDc3IEdnRpZANVSzAyNTVfMjU1/SIG=123f2f7rt/EXP=1162639429/**http%3A//curious.astro.cornell.edu/blackholes.php