what do you expect to be in the center of a black hole?
440519
I believe that everything (not even light can escape; that's how strong the gravity of a black hole is) that is sucked into a black hole turns into "singularity" which has an unimaginable mass.
762962
no, but i can tell you what we think it is:\n\nit is a star whose gravity is too great for the nuclear fusion in its core to negate.  it collapses in on itself and goes supernova.  then it is a neutron star.  if the gravity is still too great, it collapses some more and becomes a black hole.  its gravity is so strong that light itself cannot escape it (thus it is 'black').  they are suspected to be at the center of many galaxies, especially quasars and other active galaxies.  one is believed to be at the center of our own galaxy, the milky way.\n\nonce again, no one has really seen one, just the indirect evidence that one exists (strange star orbits, gas being sucked into nothing, strange bursts of some kind of rays (can't remember what kind) coming out of the poles, etc.\n\neverybody is pretty convinced that they exist.  its just kinda hard to prove.\n\nps the idiot down there who said black holes are dead galaxies has no clue what he is talking about. please ignore him.  and its not the size of an atom, its an infinitely small point, the swartzchild point.
358053
Intense gravity. It just sucks everything nearby up. If you went into a black hole gravity would be stronger at your feet than at your head. You sould be stretched out like a piece of spaghetti and broken in two. Then the same thing would happen to the pieces of you. The bottom of the pieces would break off untill you're just a bunch of little tiny pieces.
555330
Travel close to the speed of light or get really close to the event horizon of a black hole.\n(Well, you DID ask it in the physics forum!)\n\nIf you just want to relax, why not spend some time on Yahoo! Answers!!!!! It's fun.\n\n\n:)
573101
Small black holes will have larger tidal forces. They also have have a larger amount of Hawking radiation. The radius of a black hole is determined by the mass of the black hole. Larger black holes are typically at the centers of galaxies. Smaller black holes are more randomly positioned.
571912
Good, very good!!\nJaxon is very right.\n\nAdd few things:\n\n1. Black holes are the least understood entities and by nature human beings perfer to know about unknown.\n\n2. Neutron stars and black holes are closely related, they differ in amount of gravitational pull.However neutrn stars are visible and so are being reffered as a paddestal to understand black holes.\n\n3. As jaxon pointed out black hole may indicate end of univers: be clear, end of universe in terms of time not boundries or limits.\n\n4. Generally Black holes are present in the centre of glaxies so they help in understanding the creation of glaxies.\n\n5. As referred by jaxson about light: Be clear that the gravitational pull of black holes is so great that light can not escape out of a black hole.\n\n6. The postulate in the theory of relativity regarding deflection of light path under the influence of greavity is is witness near Neutron stars and black holes.
752294
The event horizon of a Black Hole is spherical.\n\nThe circumference is 2 pi times the radius, where the radius here means something rather different than "the distance to the center", since space is so warped.\n\nThe radius is proportional to the mass of the black hole (not the cube root of the mass, as you might at first think).  The radius is about 10 kilometers for the mass of the Sun, so 20 kilometers for twice the mass of the Sun, etc.
486631
Assuming this is possible the end positioned inside the event horizon would be broken down into it's individual atoms and would cease to exist.  However some scientists (me being one of them) think black holes are only one end of a worm hole and that when you reach the event horizon you are expelled out of a white hole into another universe.  Think of a white hole as the polar opposite of a black hole, instead of consuming every thing it expels everything
474017
An event horizon is the theoretical visible edge of a black hole.  A black hole is a mass so dense that its gravity will allow nothing to escape, not even an object travelling at the speed of light, not even light itself.  An event horizon is the boundary of a black hole at which light can still escape.  Therefore we could see everything that happens up to an event horizon, in theory.  Beyond this boundary, light is drawn back into the super-dense mass and nothing can be seen.
989306
A very good question but one that we don't know the answer to yet.  It is a hypothetical situation that could create a wormhole or perhaps the center of a blackhole is where this kind of phenomenon occurs.  The bottom line is that there is no hard evidence of this but it seems possible according to mathematical models.
557703
Black holes are huge concentrations of mass in a very small area.  So small that it is too small to contain conventional matter as we understand it.  There is a perimeter around a black hole known as the event horizon.  Beyond this point, nothing, not even light can escape the gravitational pull of a black hole.  If you were to be able to stand on the event horizon and have telescopic vision like Superman, looking tangent to the event horizon, you would see the back of your head.
1169308
It's a planet.  Planets are too small to be blackholes.  I will ignore the second part of your question.
359590
The short answer is that whenever we take a good hard look at any given galaxy, we find good evidence that there is, or could be, a black hole at it's core.\n\nThe long answer is:\nIt is not so much a theory as something being increasingly noticed. Because black holes are the latest and coolest thing in astronomy (just look how many questions about them appear here!), everyone is always looking for them. They are not so easy to find because, well, they are black. You can't see one directly. One way to tell if there is a black hole there is by the effects of it's gravity on nearby matter. So far, the biggest effect observed on nearby matter has been high energy radiation caused by the rapid acceleration of that matter as it falls into the black hole. Some galaxies show that in their core, indicating a massive black hole there.\nAnother effect is that stars could orbit the black hole, just like the Earth orbits our Sun. We have known for a long time that all stars in a galaxy are orbiting around the center of that galaxy. IN the past it was assumed that there were enough regular stars and dust and gas in the center of the galaxy to make a mass big enough to orbit around. But recently observations with more powerful telescopes of stars closer and closer to the center of our Milky Way galaxy have shown stars VERY close to the center of the galaxy orbiting VERY fast. In that case it is easy to calculate the mass of whatever it is that they are orbiting, just like we can calculate the mass of the Sun by knowing how fast the Earth orbits it. Those calculations show the mass is millions of times more than the sun. Now we know all that mass has to be in an area smaller than the orbits of those stars, and the size of those orbits is measured as being quite small, so we know the volume far too small to be a big star cluster or other ordinary concentration of mass. The only known way to get so much mass in such a small volume is a black hole.\n\nI recall many years ago, when computers were just becoming powerful enough to do big simulations, that someone tried to simulate a globular star cluster by programming a few thousand stars to orbit in a big ball with no mass other than the stars themselves. It didn't work. The stars kind of just all dispersed at random and did not stay in a nice ball shaped globular cluster. Now it should be obvious that if there was a massive black hole in the center of the globular cluster, then all the stars could orbit it like the planets do the Sun, only not all in one plane like the planets do. And I believe some evidence of medium large black holes has been found in some globular clusters recently by the same method of using powerful telescopes to look at the orbits of stars very close to the core. And after all, what is a globular cluster but a really small galaxy.\n\nSo giant telescopes, some of them is space, are providing data never before available that just makes it more and more reasonable to assume that all galaxies have a massive black hole at the core.
767654
that's one theory.a black hole was the result of the big bang in every universe.it eventually swallowed other black holes to expand the universe.every known universe has a black hole in the center.if they become active they could destroy the universes around them as well as the universe they reside in.this would include our own universe.
138345
Just about all astronomers agree that at the center of our Milky Way Galaxy (and probably at the center of most other galaxies) lies a supermassive black hole. It probably has a mass at least 2-million times that of our Sun, and is approximately 96-million miles in diameter.\n\nThese figures come from careful observation and measurment of the motions of other objects near the galactic center.\n\nThis page has more info, plus a photo ---\nhttp://antwrp.gsfc.nasa.gov/apod/ap021018.html
960972
The denser the black hole, the larger it's event horizon would be.\n\nApplying the Einstein Field Equations to collapsing stars, German astrophysicist Kurt Schwarzschild deduced the critical radius for a given mass at which matter would collapse into an infinitely dense state known as a singularity. For a black hole whose mass equals 10 suns, this radius is about 30 kilometers or 19 miles, which translates into a critical circumference of 189 kilometers or 118 miles.
790352
click here:http://en.wikipedia.org/wiki/Rotating_black_hole