well even if nothing went past the event horizon, the gravitational pull would still continue to grow because matter DOES get closer and closer to the event horizon, so the effects would be similar

Could there possibly be a star that exists in the universe that has such an immense mass, that it could behave in the same characteristics as a black hole? Or does a black hole simply come into existence after the explosion of a star, and there is nothing else in the universe with characteristics like a black hole? I'm just extremely curious and intrigued by this conversation. I know there are brown dwarf stars, which do not have any sort of luminosity, but immense amounts of mass, simply extinguished stars, not stars that have exploded. These massive dull stars must have some sort of immense gravitational force?

Also when matter is sucked into a black hole, is it compressed into a singularity? Or is there another process?

This post was edited by Jazz_Thing on Mar 30 2009 05:48pm

brown dwarf stars are stars that were not massive enough to form a neutron star, however it was not massive enough to become a neutron star and has stopped fusion. it is like to already have exploded, and the remant star is simply the remaining matter that was not ejected during a nova. as one of the guys above have said, we do not know what happens once matter has gone passed the event horizon (if it does at all) since it is completely unobservable

as for your first question:
the reason black holes exist is because the density of the singularity. a super massive star that becomes a black after it explodes, does not exhibit black hole characteristics because of the distribution of matter. a black hole has one single point of mass meaning ALL the gravitational attraction is directed from that point, where as a sun has the mass distributed throughout the entire sphere, so the gravity within the volume of the star largely negates itself which prevents an event horizon. without proper knowledge in physics regarding vector forces this concept becomes exceptionally hard to grasp, and even more so over the interwebs

this brings up an interesting question. no there isnt fusion like in a star taking place, but what happens to the matter that collapses and becomes the singularity? what kind of processes could be going on in there? this will probably only be discovered (if at all) on paper.

Kam, you have an extensive knowledge of black holes, I'd like to ask one last question what exactly is a singularity? And what is its role in the universe?

Also, is space itself mass distributed about a universe? This is startling to ask because that would imply that the universe is finite, I'd also like to hear what you think or what you know about the universe being finite or infinite, thank you for contributing to this thread.

a singularity is essentially mass that does not occupy volume. quite litterally, a singularity such as on in a black hole, occupies 0 volume. thats why the gravitiational pull is infinite at certain lengths. (the "black" part of the black hole) due to the gravitational force equation (G*m1*m2/r^2) as the density (or distance between the objects in a black hole) shrinks down to 0 the gravitational force explodes into infinity. eventually at a certain distance from the black hole, the equation returns to normal and no longer becomes infinite. this distance is the radius of the event horizon. now, why it stops at a certain length, or how does it theoretically occupy no volume? im not sure, ive just read several scientific articles saying it does. as for its "role" in the universe: im not sure i get what you mean. what it does in the universe, or how it affects it, well it warps space-time in such a way that it is second to none.

this picture might help
http://nrumiano.free.fr/Images/bh_warp1_E.gif
note how the neutron star bends the "fabric" much more steeply. essentially a black hole bends it vertically, such that its slope is "infinite" and thus nothing but an unstoppable force could overcome it. eventually it evens out just like the two in the picture, and the event horizon ends.

and i dont quite undertsand your last question



by the way, NO star fuses any element heavier than iron. heavier elements REQUIRE energy in order to fuse, rather than release energy in fusion like the lighter elements do. this is why we use fission of large elements and fusion of hydrogen to release energy . for instance, the atomic bomb of ww2 was a fission bomb: a large element like uranium is shot with neutrons under extreme conditions and undergoes a decay to barium and i believe kryptonium. because the very heavy uranium underwent fission it released roughly the energy required to fuse barium and kryptonium.
in a hydrogen bomb however, the energy of a fission reaction is used to create the temperatures and pressures similar to the core of a sun, and produces a fusion reaction of hydrogen. this fusion releases a MUCH greater amount of energy roughly equal to the amount of energy needed to break helium into hydrogen.

heavier elements in the universe are created by the novas of various stars. since the temperatures and pressures are far greater than the core of the star (even if for a small while) it creates enough energy required to overcome the activation energy of fusion of the heavier elements.
in essence, it takes energy to break small atoms, and combine large ones.
and releases energy to fuse small atoms, and break large ones

This post was edited by Kamikizzle on Mar 30 2009 10:20pm

That is incredible i enjoyed every bit

some people like to look at gravity in a different way just to help grasp the concept.

have you ever seen those planes of lines that cross over one another? its supposed to look flat, and the heavier the object placed on it the larger the distortion it makes

Exactly, what is the fabric of space time made of? I'm talking about to the extreme subatomic level, do we have the knowledge to even grasp that sort of information? Is it strings or what?

Also, what is the role of star nurseries, and could possibly a black hole come into existence out of these nurseries, i.e a star instantly becomes a black hole out of its formation? I know I'm just chock full of questions, but this is so intriguing!

Here is a picture of a star nursery:

star nurseries are like galaxy sized chucks of largely hydrogen and helium gas. after millions of years gravity attracts the gas together until theres solar system size clouds of the stuff, and eventually forms a disk of gas circling about a center. when the center is massive enough the heat and pressure begin fusion and a star is born. blackholes dont form in here without the collapse of a star because they start fusion much earlier than they have the time to grow large enough to collapse on itself. note that during this process, the star can begin fusion and still have a large disk of gas around it. so it can still grow much larger even after its ignited

http://www.whatsnextnetwork.com/technology/media/star_formation_02.jpg

this is an illistration of the center (the infant star) with gas circling about it