black holes?

Question

how big are they? can you get white holes and whats a worm tunnel?

Answer 1

Black Holes or Wormholes?
The nature of black holes, or even whether they exist, is a rich area of speculation among physicists. In a New Scientist exclusive article, physicists from Germany & France reveal that their recent study has shown that a wormhole - a spacetime distortion that connects different areas through a "shortcut" - would in fact mimic black holes so precisely as to make it virtually impossible to tell them apart.
This isn't necessarily that surprising, given that the first formal explanation of a wormhole-like structure was the Einstein-Rosen bridge, which formed with a black hole that was connected to a distant white hole which expelled the matter pulled into the black hole. Such models were found to be unstable, however, unless there is introduced some other element, such as negative energy or matter, as a stabilizing force within the hole itself.

Many of the factors that have been normally used to classify an observed astronomical object as a black hole, according to the new study, would actually manifest essentially the same for either of the two objects. Even physicists who believe the current objects are black holes seem to indicate that, with current technology, it's a practical impossibility to tell between them for certain.

About the only way to know for sure is to send a probe into one, but due to the spatial distortions of both phenomena receiving transmissions from such a probe would be problematic ... meaning that, for now, the truth will have to remain ambiguous.

Answer 2

A black hole is a point of massive gravity, so large that even light cannot escape its pull thus "black" hole.

They come in varying sizes.
There is a supermassive black hole at the centre of most galaxies generally constituting about 0.5% the mass of the entire galaxy.
It is believed that there is a relation between the size of a galaxy and the mass of the supermassive black hole at its centre.
There can also be smaller black holes inside the galaxy or anywhere else.
They are generally formed when a star collapses in on top of itself.

White holes are not a theoretically accepted phenomeon.

Assuming by worm tunnel you mean worm hole:
A worm hole is a rip in space and time.
It connects two different points in space and possibly time together.
A worm hole is a thoeretical phenomenon and has not been observed in nature.

Answer 3

If a black hole could exist it would have no limit to size.
A black hole would eventually accrete all the matter in the universe and sit forever doing nothing.
You could never get rid of a universe if a black hole could exist. The universe is a finite entity.
A worm hole requires a singularity and a singularity needs a black hole so neither one is a viable entity.

Answer 4

The singularity inside a black hole has zero size. The event horizon surrounding the singularity can be enourmous.