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View Full Version : Anatomy of a black hole



jst5150
03-24-2008, 10:05 PM
Some great animation here. Some words misspelled, too, but still done well.

http://www.thinktechnologies.com/portfolio/demos/Blackhole.swf

DeaconBlu
03-25-2008, 08:43 AM
Hey that's pretty cool. If the wormhole theory is correct, wouldn't we see alien life just on the cusp of getting sucked in to the wormhole? Like a couple competing refueling stations, maybe five or ten different alien fast food joints and at least two 24 hour breakfast joints. There'd have to be a couple different size and shape restrooms. Maybe even some skanky alien prostitutes?

Just spitballin' a buddy story.

lpetrich
04-04-2008, 12:20 AM
Somewhat oversimplified, but broadly correct. I'm familiar with general relativity and some black-hole physics, so I'm in a good position to judge. :)

Stellar evolution is much more complicated than what it described, but it would be hard to squeeze very much detail into a few frames. Maybe instead of just saying "hydrogen", say "hydrogen, then helium, then carbon and oxygen, then silicon and the like, then iron", but even that starts getting long-winded. Perhaps "hydrogen, then other materials, then iron."

It gets right that an infalling object observed from the outside would seem to take forever to reach the black hole's event horizon, as it's called. It would get very redshifted and dim over a timescale that's approximately the infall timescale at the event horizon, however. This is about 10 microseconds for a solar-mass black hole, and it is proportional to the object's mass.

The first and most straightforward possibility is falling into the black hole's singularity. It's called that because in classical-mechanics gravity, it's expected to be infinitely dense. However, collapse to it will run into quantum-gravitational effects at Planck size scales, about 10^(-35) m, and those aren't very well understood at all. In fact, quantum gravity in general isn't very well understood.

The second one, being shot out the other side, I haven't heard of, but it may be possible. An important question is how much an object would be squeezed as it passes through.

The third one, going through a wormhole, is rather intriguing, but there are two questions for using one to travel. Will it be stable? Will its tidal forces be tolerable? If a wormhole must be stabilized by quantum-gravitational effects, then it will have Planck size scales, meaning that all structure of an object passing through will be crushed -- all macroscopic structure, all atomic structure, all nuclear structure, and all hadronic structure will be crushed out of existence.

Melisande
04-05-2008, 02:17 AM
The second one, being shot out the other side, I haven't heard of, but it may be possible. An important question is how much an object would be squeezed as it passes through.



I might sound really ignorant here, but I wonder how anything can pass through something that is so dense that not even light can escape it.

I mean, if I were to enter the atmosphere of Jupiter I would get crushed by Jupiter's gravity. And if I were to approach a black hole, I am quite convinced that I would be equally crushed, only further out, and of course not in an 'atmosphere'. And how could I escape "on the other side" if I was already crushed, dissolved, obliterated, had gone up in atoms?


The third one, going through a wormhole, is rather intriguing, but there are two questions for using one to travel. Will it be stable? Will its tidal forces be tolerable? If a wormhole must be stabilized by quantum-gravitational effects, then it will have Planck size scales, meaning that all structure of an object passing through will be crushed -- all macroscopic structure, all atomic structure, all nuclear structure, and all hadronic structure will be crushed out of existence.

Again, how can something so massive act as a door, or gateway? The little I know (though I don't really know as in being educated to know) about wormholes is that they can actually be found almost anywhere, but the energy needed to open them is immense, far beyond anything we can produce to send even a couple of atoms through. Isn't it more feasible to speculate about using the radiation from a black hole as an energy source? From a safe distance, of course.

Ruv Draba
04-08-2008, 03:46 AM
I might sound really ignorant here, but I wonder how anything can pass through something that is so dense that not even light can escape it.

Melisande, there are some interesting links on wormholes here (http://casa.colorado.edu/~ajsh/schww.html)and here (http://en.wikipedia.org/wiki/Wormhole). My days of actively reading in physics are long over, but I understand them to be speculative artifacts of mathematical models. Unlike black holes which can be verified, wormholes have not been verified to exist. And even if they exist they may not be travellable - you could die or be trapped in their middles - but you might be able to see light from two different universes before you went.

Hope this helps.

kullervo
04-11-2008, 04:48 AM
Wormholes and black holes are best separated somewhat. Wormholes are the theoretical connections between remote sections of spacetime. Unfortunately the term has been used to describe the 3D illustrative projection of the descent into a black hole as though it were in a 2D universe. Like the funnel-shaped bend of a flexible fabric supporting a weight.

Unfortunately, what you find as you approach a black hole is that what you fall into isn't empty. True, you pass beyond the boundaries of normal physical laws as you pass within the event horizon, but at the end of your rather nasty journey is a very dense object: the collapsed star. So rather than popping out again somewhere else, you are ripped apart limb-by-limb and atom-by-atom before colliding with the object within.

If wormholes exist, black holes may have something to do with their formation. But I'm not going down one.

Bad trip.