Black HOLES

[midgetwars]

Out of curiosity

 

IS a black hole literally a hole and there is like a compartment behind it???

 

And What is behind a black hole considering that the black hole isn't literally a hole?

[Gilded]

A black hole will appear as a black, light bending sphere in three dimensional space due to it's event horizon (the region past which light can't escape):

 

 

I'd imagine the "hole" refers to how it looks when the spacetime bending effect is visualized like this:

 

http://wyp.dep.anl.gov/Story13-16/Husain_files/image004.jpg

Or I suppose it could just mean those cavity kind of holes like there are in Swiss cheese.

 

As to whether it has a "compartment" behind it, or what actually happens at the singularity, isn't known yet as understanding it requires a solid theory of quantum gravity.

 

A lot more info about black holes can be found at Wikipedia: http://en.wikipedia.org/wiki/Black_hole

Edited November 25, 2008 by Gilded

[midgetwars]

What do you people think is behind a black hole???

 

THEORETICALLY of course?

 

THANKS TO ALL ANSWERS

[RAJESHKUMAR110]

what is black hole? How it is formed.

[midgetwars]

I don't know the technical terms,

 

but in basics : A black hole is a hole that can suck anything into it, not even light can escape the hole.

 

CORRECT ME IF I'M WRONG

[Klaynos]

Have a look at my blog:

 

http://blogs.scienceforums.net/anewworld/2008/03/21/stellar-black-holes-some-myths/

 

"theoretically" has a very precise meaning in physics. The singularity at blackholes means the theories break down, and we don't know what's going on.

[midgetwars]

When I mean theoretically i mean what do you think??? NOT PRACTICAL

[Klaynos]

When I mean theoretically i mean what do you think??? NOT PRACTICAL

 

Then the word your looking for isn't theoretically, you're asking for people to speculate. And imo we don't have anything like the information required to speculate with any good chance of being correct.

[Edtharan]

A Black Hole is a region of space where the Gravitational Field is so strong, anything that comes within a certain distance from its centre will never escape.

 

For instance, if you compressed our sun to less than 3km across, then anything that came within that 3km region would never escape. However, outside this area, the gravity of the sun would not change. Earth would continue in its exact same orbit, just as if the sun had not been turned into a black hole.

 

The reason this occurs (well the most common reason we know of by far) is due to gravity. Gravity is the weakest of the 4 known forces, but it is universally attractive (where as the others have repulsive effects along with the attractive effects). Because Gravity is always attractive, it means that with enough mass, you can get truly "astronomical" forces.

 

To give you an idea how weak gravity is, you can take a small fridge magnet that weighs only a few grams and the attractive force between it an a piece of metal can hold it own weight against the entire gravitational force of the Earth that weighs around 5.9736×10^24 kg. However, you can get far force out of gravity because it always attracts where as magnets can also repel.

 

Gravity follows the Inverse Square law. This is the principle by which the strength of gravity is inversely related to the square of the distance from the centre of mass. The result is that if you double the distance, you get 1/4 the force, or if you halve the distance you get 4 times the force.

 

So if you were to cause the Earth to shrink to 1/2 its radius, then the strength of gravity at the surface will be 4 times (4g) what it is now. Or if you expanded the Earth up so that the radius was 2 times the radius, then gravity would only be 1/4 of what it is today.

 

According to Relativity, gravity is caused by the warping of Space Time. This is a bit hard to imagine and many attempts to do so suffer from oversimplification (like using the analogy of a rubber sheet) and so aren't exactly correct (so don't assume that because you understand the analogy that you understand what is being demonstrated by the analogy).

 

To understand it better you need to understand Geodesics. Put simply a Geodesic is the shortest path between two points that follow the surface. On a flat surface this is a Straight line. On a curved surface a straight line is called a Geodesic.

 

In a vacuum, light follows the Geodesic (always takes the shortest path between two points). If space is curved, then light will appear to curve.

 

Near a black hole, the amount that light will curve will cause it to always curve back in towards the black hole if it is within the "Event Horizon", for the Sun, as I said earlier, is around 3km from the centre of its mass (but as the sun is far bigger than this the sun won't turn into a black hole).

 

If you were to draw the geodesics for this region of space, inside the Event horizon, then the lines would form a sort of spiral in towards the "Singularity" (centre of the black hole).