Assuming einstien is correct, which he seems to be batting 1000, it is useful to think of it as a tear in time space yes they can very in size, whether or not a singularity is possible is beyond human comprehension and also beyond that of mathmatics. Blackholes in therory do not contradict the law of entropy due to hawking radiation, and seem an inevitable product with the current understanding of the laws governing the forces of the universe. Thik of your bath tub anaolgy, if there is more water in the tub aka matter to fall into the black hole than you could say the black hole is larger just as the drain will extend a larger votex, as to what happens on the other side is not known.

I think for the most part its an analogy to understand the incomprehensible. Its obvious that space is indeed bent by gravity as astronomy has shown as well as the effects on time which have to be accouted for the differnces of a satelite orbiting the earth to have them work correctly. It has been demonstrated that a cloak on top of a water tower and one at ground level disagree.

Ain't it the truth, Brothah!

Dark matter mapped.
http://www.youtube.com/watch?v=gCgTJ6ID6ZA&feature=related
Dark matter Ring.
http://www.youtube.com/watch?v=EJtJ7Q0cV34

I Just took a quick glance at the things being said on here, I would tend to think that almost all of this black whole thing is speculation. Has anyone ever seen one?

A singularity is tough to define. In gr, the theory breaks down there at those points, where the theory is said not to be applicable. It's not really that they say that black holes exist, but when matter gets dense enough in this regime, infinities become apparent in the equations. When dealing with gravitation fields, this means that the light reaches a point where it can't escape, but this is a conclusion from the result of calculations that are the weak points of the thoery from a mathermatical-modeling point. The same thing happens in sr when a body is not able to reach the speed of light; a body gains more and more mass, and resists acceleration more and more, so that as it approaches, but never reaches, c, and as it does so time grinds to a halt, just like a black hole, and sr is just a special case of the general theory. So one could also say that black holes are entities that the theory of relativity just doesn't know about, doesn't talk about, and hardly concerns itself with. But that the point that these solutions are valid in the fact that they predict what we see in nature, to a degree, can be seen as experimental confirmation. In nature there appear to be these regions that have behavior like the things we don't know about in our leading gravitional theory.

Your expample of a sewer drain is very interesting, mostly because the water does go somewhere. Inforamtion is expressed as staying on the surface of a black hole, but the commonly held opnion is that things of matter do actually fall into a bb, and when they do they increase it's mass and behave like normal systems. They have heat content, and also radiate energy. The most interesting thing, I think, about bb's is that the possibility, in thought at least, of them having two sides is now on the dabating table. They could be periods of time in which the laws of nature re-adjust. One option espoused by physists is that quantum fluctuations bounce the or a universe at each contraction and expansion event. This has math and is in the literature. Another possible option is that the blackholes are naturally selected. That is, in a given universe, only such and such conditions allow for bb's to form, and the only thing taken from evolution in this scheme is that universes that have batter conditions for having more bb's will have come from one that had a lot in it too. This actually limits the size of bb to about two solar masses, a result that has not been contridicted by experiment.

But what is so bad about speculation. Where math is absent, and no one is talking about the math or landscape of the area inside a black hole yet, there is plenty of room for thinking about new options. One could say one hasn't seen an atom yet either, though I think I remember a blurry picture that was color treated to show some blurry and bumpy regions that was a photograph at atomic level. Black holes are established enough as an identity, if a bit of unknown one or enigma, that science must begin to offer more satisfactory grounds for their explanation. An idea that avoided singularities or horizons or boundaries would be most appealing! But as yet such is not present, so thinking caps must be dawned.

Bb's represent in my mind an occurence when the development of physical laws change more rapidly than otherwise. I see a region before our big bang, but it is not one readily expressible in maths or even a quantitative way common of thinking scientifically. If laws develop and are set into place in condensed gravity situations, there should then be some trace to follow. Perhaps mass changes with time, and then the optical effects of excited electrons would show different intesities if they had different orbital properties, or tests such as that which look for things being different in the past that are still observable today.

The main problem with black holes is that our current science views them as curious anomalies. When we understand spacetime better, which I think should be done away with, I'd imagine that blackholes will have been explained in a new light as well. But they do offer a class of new thinkers a very intriguing opportunity for new ideas, which must also bear the weight of experimental testing. You could try to do away with black holes, prove them impossible, but what would that really say, that things which we have good evidence and reason to believe are in reality are not explained by our current qm theory? The whole issue of the singularity and gravitational collapse beckons at one thing, and that is a deeper underatanding of fundamental physics.