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Rulato
07-10-2005, 04:15 AM
Hi,
I need information on how black holes work and if it would be plausible to use one as a sort of transportation device through space?

robeiae
07-10-2005, 05:40 AM
This has actually been suggested by scientists, in a way. A black hole is a star that has collpsed inward upon itself...gravity so strong, not even light can escape. But no one has ever been inside a blackhole. What happens at the center? It has been suggested that the center could be some kind of "rip" in the space-time continuum. Now this is off the top of my head, so you more knowledgable AWers can correct me if I am in error. Still, I think that you could find some real science to back up your idea. I take it you're doing hard Sci-Fi?

Here's a good link with the basics:

http://www.damtp.cam.ac.uk/user/gr/public/bh_home.html

Rob :)

Meantime
07-11-2005, 05:16 PM
At the center of a black hole is thought to be a singularity, a point where space-time becomes infinite and the laws of physics break down.

I remember reading essays by Hawking and others that obliquely discussed the possibility of traveling back in time due to the effects of a singularity - read Hawking's theories and work your way back, there's a good deal of mathematics involved which I can't adequately describe, or even grasp sometimes.

MadScientistMatt
07-11-2005, 05:44 PM
"A black hole is where God divided by zero." - Anonymous

Short version of what a black hole is: A black hole is a massive, dense object whose escape velocity is higher than the speed of light, and that's really all that you need to establish that it is a black hole.

More details. The black hole has what is known as an event horizon, the boundry where the gravity is so intense that not even light can escape. Outside of the event horizon, a black hole's gravity behaves just like the gravity of any other object, like stars or planets. If you replaced the sun with a black hole of the same mass, the planets would still orbit it in exactly the same way. In order to get sucked into a sun-"sized" black hole, an object would have to be on the same sort of trajectory that would cause it to get sucked into the sun. The same goes for black holes of other size - if you had a miniature black hole with the same mass as a comet, only objects that came close enough to be captured by a comet would be captured by the black hole.

The event horizon is located at a distance from the center of the hole called the Schwartzchild radius. This radius is found from the formula for an escape velocity (I could post that here if you're interested). The Schwartzchild radius is the distance where the escape velocity is greater than the speed of light. Consequently, nothing in known physics can get out once it passes the event horizon. If you're inventing newly discovered physics for you book, a ship with a faster than light propulsion system might be able to activate that system from inside the event horizon and escape. This would depend on how the system worked and whether the ship could survive the tidal forces.

Even though it would probably be possible to take a spaceship on a course that would come close to the event horizon without getting sucked in, this still would not be a good idea due to an effect called tidal forces. Gravity follows an inverse square law, diminishing with the square of the radius. A ship flying past the event horizon would experience a much higher level of gravity at the side closest to the black hole than the side furthest from it. The difference in gravity would create very large stresses on the ship's structure, basically stretching it parallel to the gravitational field. These stresses are pretty high and can tear a ship in two. Or the crew members, for that matter. Note that very large black holes would not have such extreme tidal forces until you get inside the event horizon.

There have been some speculations that since the space-time continuum is so heavily distorted around a black hole, the black hole may be an actual hole in the space-time contiuum, leading to another part of space. However, using it as a transportation system would be rather risky. For one thing, it would probably exit at another black hole, so you wouldn't be able to escape the exit. Second, the tidal forces would be so severe that it is unlikely for the ship to survive even approaching the black hole. And to top it off, any theory that the hole might "go somewhere" is pure speculation.

There's a lot more about these that I could post if you're interested.

Rulato
07-14-2005, 07:19 PM
Thanks everyone for the info. I would like to know more Matt if at all possible including any formulas that could apply.

Janice

Meantime
07-15-2005, 11:20 PM
Janice, you may also want to study "naked singularities". These are singularities not hidden within a black hole's event horizon, which may make your time-travel scenario more realistic than approaching a black hole, figuratively speaking. Shapiro and Teukolsky used a computer simulation to show their possible existence in 1991. There is still no theory governing what a "naked" singularity would appear like, so you can use your imagination, nobody can prove you wrong.

mschannon
08-31-2005, 10:43 PM
You've gotten a lot of good responses from a scientific POV, but remember that, according to modern physics it's impossible to travel faster than the speed of light (well, it's more complex...but no one can conceive of how to get a spaceship to fly faster than the speed of light) but it's been a standard of science fiction since E.E. Doc Smith!

So enjoy and create some scientific breakthrough that allows someone to use blackholes as transport stations. It probably would be stretching it too much to use them to transport anywhere--unless your new technology had a "focusing" device that harnessed the energy in a black hole and spit you out at whatever coordinates you put in. Good luck.