what is a black hole?

Question

I have alwas been interested in astronomy and would like a complete detail information on it. Please anwer the question OR refer to a website.
Thank You

Answer 1

Any mass contained in a radius smaller than its schwarzschild radius,

r_s = (2GM/c^2) with

c= the speed of light, G = the gravitational constant and M is the mass of the object.

The schwarzschild radius scales linearally with mass (an object twice as massive will have twice the schwarzschild radius) and to get you started, an object the mass of the sun (2x10^30kg) has a Schwarzschild radius of 3 km. In otherwords, if you jammed the sun into a sphere 6km across, it would be a black hole. The schwarzschild radius indicates a volume of space where the escape velocity from the mass in question is the speed of light or greater. Using the linear scaling, an object the mass of the earth (6(?)x10^24 kg would have a schwarzschild radius of about 1/300,000 of 3km, or 1 cm.

Black holes have some peculiar properties, such as evaporation, extremely strong tidal forces near their central singularity (but weak tidal forces at the schwarzschild radius of a supermassive black hole). Things can happen inside of the schwarzschild radius too. For instance, if our universe was closed (not expanding enough to continue expanding forever) it is technically inside of its own schwarzschild radius (we would be living inside a huge black hole.)

It is called a black hole because no light that crosses the schwarzschild radius can completely escape the mass to an infinite distance. (This does mean that if you are just outside the schwarzschild radius yourself, you CAN see light that is emitted from within it, or passes within it as long as it is not too close; only an observer at d= infinity cannot.) Thus this volume of space appears "black." You can read more about black holes on wikipedia at http://en.wikipedia.org/wiki/Black_hole.

The concept of an object with gravity so great was first conceived by a little known geologist named John Michell. The better known Simon Laplace took the idea and ran with it in a book years later and so is often credited with coming up with the idea.

Answer 2

A black hole is a hole in the universe that is black. Well this description is not so helpfull after all since almost of the whole universe is black with many stars on it. The method used by astronomers to find a black hole is indirect. X-ray observations of certain parts of the universe show that some objects radiate X-rays around them but in the middle they are black. The space telescope to do extensive observation in x-ray activity in the universe is called the Chandra observatory. The image that we is from the pictures coming from the Chandra are in the range of light that our eyes can't see it. We are able to see only the visible spectrum from about 400 nm to 700 nm of wavelength light. The computer generates an image so that we can see the pictures of Chandra. So the theory of a black hole is as follow: a giant star undergoes fission just like our sun, resulting in a bulging sun that eventually collapses on its self. The reason that the star collapses on itself is related to center of gravity being in the center of the star. When the particles fall back and are forced to accumulate in a very dense much smaller diameter than the star itself. Imagine taking the size of the whole earth and forcing it to fit in a area as big as a football field. The disk is so dense that the gravity reaches almost infinity. Then here it is where the weird/cool thing happens. The light traveling close to such an object is sucked in. The X-rays that we see in the images from chandra observatory are the trails of gas and particles being sucked in the black hole at great speeds. The black hole will eat up any mass that is close to it. There are more intriging things that happen at this point but I am not so sure about it. And a final black hole is a gate believed to lead to another universe. The hypothesis is that if you go close to a big, stable black hole, you can go through its "eye" and in the other side of this "tornado", you have time and space flipped where you are able to go to any point in time but in only one direction, towards the opening of the black hole. .

Answer 3

A Black Hole is an object with a mass great enough to have an escape velocity in excess of the speed of light. The gravitational field is so strong that it can suck light into it, thus the blackness.

Answer 4

at the center of all galaxies there is a sphere shaped area that has a density and gravitational field so strong that it even holds the electromagnetic energy waves of light, it spews out material from it's "poles" at near light speed (a weird one is that all the stars and solar systems that rotate around it revolve at the same speed, usually things spin faster as they get closer to the center; but not when it comes to galaxies)

Answer 5

No one can say. There are of course the usual theories: A gate way to Parallel Universes. The gate way to Hell. The world may never know.

Answer 6

no one has even been close enough to definitively say if they even exist or do anything. It's all speculation and probably bull$hit.