What's at the other end of a black hole?

[Gunhead]

Relative to whom

relative to an unladen swallow going at terminal velocity.

European or African swallow?

And what did the do to the coconut?

-Gunhead

[CJvR]

Where does the "light go" when you turn off your electricity?

Where does it go when you keep the electicity on?

[InnocentBystander]

Acutally... I think the light gets "stuck in orbit" so to speak. There is a picture in my old physics books, mabye I'llscan it tonight, doubtful. We are pretty sure that gravity bends light. In the case of a black hole the light gets bent very far... so far in fact that it would appear to be going in orbit around it. Mabye I can fish up the picture on google or altavista.
This should work. Those rays are lines.
Notice the red line in this one (the one flung into orbit, sucks for him, hehe) That should really be all you need to understand "where the light goes".

[aten_vs_ra]

Ask the astronmer. Scroll to the bottom, this is some good shit.

[Kuroneko]

Uh, OK, so the wormhole inside a black hole is a myth?

Sort of. The Schwarzschild solution is the classic simple black hole, and it does have a brief wormhole in its maximal analytic extension. What this means, roughly, is that the Schwarzschild solution is taken literally and extended it into the infinite past and future, then it looks like two asymptotically flat regions of spacetime briefly connected by a 'bridge'--a wormhole. The problem is that interpreting this as anything more than a mathematical curiosity is unjustified, since real black holes are formed by gravitational collapse of matter, and therefore simply do not exist in the infinite past (or, for that matter, infinite future either, as predicted by Hawking radiation).

This may sound like a stupid question, but since black holes can suck in light, where does that light go?

That depends. Relative to an external observer, the light ray never reaches the horizon in the first place, so in a sense it doesn't go anywhere. If we look at it from the light ray's viewpoint, the only reasonable answer seems to be that it is converted directly into spacetime curvature. Spacetime curvature is described by the four-dimensional rank-4 Riemann tensor. You can think of this beast as a kind of "4x4x4x4 matrix" instead of standard two-dimensional nxm matrices, although there are fundamental differences in how tensors behave (but they aren't important right now). Despite having 4^4 = 256 components, only twenty of them are actually independent. What the Einstein field equation says is that there is a relationship between the mass/energy contained in space (the stress-energy-momentum tensor) and the trace of the Riemann tensor, in the analogous manner that the trace operation is defined on matrices, except in this case it produces a rank-2 tensor called the Ricci curvature tensor. The Ricci tensor only determines ten of those twenty independent components--in other words, the Einstein field equation is actually ten equations in twenty unknowns. This obviously leads to an underdetermined solution, which is where black holes come in. Isolated black holes are actually all vacuum solutions--they have no matter content anywhere (stress-energy tensor vanishes), and have no Ricci curvature either (as they must by the Einstein field equation), but they do have nonzero Weyl curvature--roughly, those ten other components of the Riemann curvature. (This grossly oversimplifies matters, but it should be sufficient.)

[Kuroneko]

Acutally... I think the light gets "stuck in orbit" so to speak. There is a picture in my old physics books, mabye I'llscan it tonight, doubtful. We are pretty sure that gravity bends light. In the case of a black hole the light gets bent very far... so far in fact that it would appear to be going in orbit around it.

True, light lenses around a black hole, so much that what one would see is a distorted view of the stars on the other side of the black hole, but that does not not mean that light gets "stuck" around the block hole. The only place for light to get "stuck" would be at exactly three-halves of the black hole's Schwarzschild radius, but this condition is so unstable that any pertubation would destroy it. Not only are conditions never so perfect, but light itself has has physical size (the wavelength). This question has actually come up fairly recently here. Still, even if light gettings "stuck" is unrealistic, it may be interesting to see how many orbital revolutions are possible if pertubations are kept within a certain range.

[GrandMasterTerwynn]

You've been watching too much sci-fi.

Uh, OK, so the wormhole inside a black hole is a myth?

That would be putting it mildly. The thing inside a black hole is a singularity. You get close a black hole, you'll be ripped to shreds by tidal forces, then your shreds will be ripped to shreds, producing x-rays in the process, then you'll go into the black hole and fall onto the singularity, forever(*) disappearing from the universe.

* - Well, this is a lie. You'll eventually make it out again . . . just one or two particles at a time, due to Hawking radiation.

[Tommy J]

You've been watching too much sci-fi.

Uh, OK, so the wormhole inside a black hole is a myth?

That would be putting it mildly. The thing inside a black hole is a singularity. You get close a black hole, you'll be ripped to shreds by tidal forces, then your shreds will be ripped to shreds, producing x-rays in the process, then you'll go into the black hole and fall onto the singularity, forever(*) disappearing from the universe.

* - Well, this is a lie. You'll eventually make it out again . . . just one or two particles at a time, due to Hawking radiation.

So a question from a non-science type guy: The Romulans are depicted in ST as using a quantum singularity as a power source. With enough shielding is this even possible? Or more technobabble?

[SirNitram]

So a question from a non-science type guy: The Romulans are depicted in ST as using a quantum singularity as a power source. With enough shielding is this even possible? Or more technobabble?

Hawking radiation, as he mentioned, means, a black hole will emit energy.

Of course, this requires a means to shield against the shape of spacetime, which is fucking absurd. Not to mention the weight issues.

[InnocentBystander]

info?

[Sriad]

... (there's an equation somewhere to estimate how long into the future, but it's a ridiculously large amount of time) ...

For an order of magnitude guestimate, you can use the equation t=(m^3)/(1000) where t is how long it will take the black hole to evaporate in seconds and m is the black hole's mass in megagrams (1000 kilograms, about a ton.). This assums it doesn't get any more matter added in.

So a question from a non-science type guy: The Romulans are depicted in ST as using a quantum singularity as a power source. With enough shielding is this even possible? Or more technobabble?

Hawking radiation, as he mentioned, means, a black hole will emit energy.

Of course, this requires a means to shield against the shape of spacetime, which is fucking absurd. Not to mention the weight issues.

...what the OoM equation tells us is that the smaller a black hole is, the faster it sheds energy, to the point where a million kilo black hole will turn into very hard radiation in about one second. When a black hole gets quite small it's gravity is fairly trivial (stand next to a mountain. Did you fall over? Right.) except when you get close, where it goes from noticable to insane quickly, and will have very rediculous tidal forces.

The benifits to using a quantum black hole are: 100% matter->energy conversion with no anti-matter to blow you up.

The disadvantages are: You have to carry around about a gigaton of black hole, you can't readily change the energy output, and you have to shoot more matter into the black hole (which will be very, very small) to compensate for the energy it gives you, otherwise it will evaporate and you'll have to cope with a few thousand tons of matter turning into energy in a couple seconds, which is not something Star Trek's ships can readily do. As for carrying the thing, you need to give it an EM charge (easy enough) and then suspend it using an opposite charge; this would cause problems with other electrical equipment and computer systems on the ship. (<-understatement)

It's a cool idea, but kind of impractical.

Of course the intense gravity would kill you long before time dilation kicks in but why be picky.

I've read some theories that postulated that in the case of a sufficiently large black hole - such as the one at the center of the galaxy - you could pass through the event horizon and not even notice.

True, but a black hole where you wouldn't notice the tidal forces even as you passed through the event horizon would need to be thousands of times more massive than What'sitsname, the Milky Way core black hole.

[Sriad]

As for carrying the thing, you need to give it an EM charge (easy enough) and then suspend it using an opposite charge; this would cause problems with other electrical equipment and computer systems on the ship. (<-understatement)

Before anyone points it out, yes you need EM shielding on antimatter type fuel, but with a black hole you're storing a looooot more mass. Also the energy collection has to happen withing the EM container, or both be the same device. Also you can never turn it off; with anti-matter if you don't have fuel in the container it doesn't need to be on, so if there's a problem you can repair it when there's nothing inside.

[Galvatron]

Don't listen to these guys! It's quite clear that a black hole is a portal to either Heaven or Hell and I have pics to prove it...

This is a black hole. Note the spaceship being sucked into it...

This and this are where you'll end up if you're a prick and get sucked in. Hell looks like a depressing place...

This is the hallway of glass you'll enter on your way to Heaven. If you're lucky, you might even see this angelic apparition leading the way. Finally, if it's not your time to die, the hallway will lead to the other end of the black hole (a white hole)...

And this is what the while hole looks like from the outside...

I hope I've helped.

[Agent Fisher]

Don't listen to these guys! It's quite clear that a black hole is a portal to either Heaven or Hell and I have pics to prove it...

This is a black hole. Note the spaceship being sucked into it...

This and this are where you'll end up if you're a prick and get sucked in. Hell looks like a depressing place...

This is the hallway of glass you'll enter on your way to Heaven. If you're lucky, you might even see this angelic apparition leading the way. Finally, if it's not your time to die, the hallway will lead to the other end of the black hole (a white hole)...

And this is what the while hole looks like from the outside...

I hope I've helped.

What are those pics from?

[Drooling Iguana]

Black holes suck.

What? Somebody had to say it.

[DaveJB]

What are those pics from?

While I can't say for certain (the links don't work), it sounds like they're from Disney's 1979 flop The Black Hole.

[Slartibartfast]

What are those pics from?

While I can't say for certain (the links don't work), it sounds like they're from Disney's 1979 flop The Black Hole.

Doubtful, in TBH there are no pics of heaven or hell and definitely no pic of a ship coming out of a white hole.

[Galvatron]

Doubtful, in TBH there are no pics of heaven or hell and definitely no pic of a ship coming out of a white hole.

Wrong.

[Sharpshooter]

No, that's definetily The Black Hole. Take a look at the first Hell image, and look at the figure standing near the top - it's that head robot on that guy's station (which he is later shown to be trapped inside of in a close-up shot sometime around then) The ship in that first image is also the same, as well as the one from the last, that one designed for traversing the hole.

You should've shown the effect of traversing the hole as well as its interior - the second anyone sees that stupid robot, they'll definetily know it's The Black Hole (cripes, that damn robot, I'm willing to bet, is the most remarkable and recognised thing about the film).

[Galvatron]

Indeed.

Here's another pic of a black hole from a distance, with two spaceships in the foreground for perspective.

Here's a close-up pic as the bigger ship is being sucked in. And another one as the smaller ship plunges into it. Note that the black hole actually looks red up close.

Finally, here's one of the interior of the black hole as the tiny ships zooms through the vortex at incredible speeds.

[GrandMasterTerwynn]

Uh, OK, so the wormhole inside a black hole is a myth?

That would be putting it mildly. The thing inside a black hole is a singularity. You get close a black hole, you'll be ripped to shreds by tidal forces, then your shreds will be ripped to shreds, producing x-rays in the process, then you'll go into the black hole and fall onto the singularity, forever(*) disappearing from the universe.

* - Well, this is a lie. You'll eventually make it out again . . . just one or two particles at a time, due to Hawking radiation.

So a question from a non-science type guy: The Romulans are depicted in ST as using a quantum singularity as a power source. With enough shielding is this even possible? Or more technobabble?

A) Yes, it is possible. Though it's less of a power source than an incredibly inefficient battery. (To use a black hole for a power source requires that you first be able to create them in the first place, and that takes a phenomenal amount of energy. Though you could "recharge" the battery, at least . . . and it's not very particular about what you're shoveling into it. Sortof like Mr. Fusion from Back to the Future.)

B) You have to shield against hard radiation, yes. Of course, this ignores the problem of how you'd move a ship around with the mass of a large mountain. And worse, how you accelerate the black hole at the exact same rate that you accelerate the starship (lest the black hole wander into the walls of its containment chamber due to it's incredible inertia . . . which would probably solve your maneuvering problems really quickly, while introducing a whole host of new ones (namely a hole in the side of your ship, and the fact that you are now out of power.)

[Junghalli]

And worse, how you accelerate the black hole at the exact same rate that you accelerate the starship (lest the black hole wander into the walls of its containment chamber due to it's incredible inertia . . . which would probably solve your maneuvering problems really quickly, while introducing a whole host of new ones (namely a hole in the side of your ship, and the fact that you are now out of power.)

Mount the black hole in the front of the ship and you could actually use it as your drive. Just let the ship fall toward the black hole while pushing the black hole in front of it as it moves, and use manuevering thrusters when you want to change direction.
Didn't somebody once speculate that the Death Star was powered by a black hole power plant?

[Hardy]

Mount the black hole in the front of the ship and you could actually use it as your drive. Just let the ship fall toward the black hole while pushing the black hole in front of it as it moves, and use manuevering thrusters when you want to change direction.

That's a violation of Conservation of Momentum. The force required to keep the black hole ahead of the ship would be equal to the force that the black hole is exerting on the ship, thus producing no net motion.

[GrandMasterTerwynn]

And worse, how you accelerate the black hole at the exact same rate that you accelerate the starship (lest the black hole wander into the walls of its containment chamber due to it's incredible inertia . . . which would probably solve your maneuvering problems really quickly, while introducing a whole host of new ones (namely a hole in the side of your ship, and the fact that you are now out of power.)

Mount the black hole in the front of the ship and you could actually use it as your drive. Just let the ship fall toward the black hole while pushing the black hole in front of it as it moves, and use manuevering thrusters when you want to change direction.
Didn't somebody once speculate that the Death Star was powered by a black hole power plant?

Wrong, wrong, wrong. Two big problems:

A) The black hole would only have the gravitational pull of its mass. A black hole with a mountain's worth of mass isn't going to be able to impart much acceleration on an object at all.

B) You still haven't solved the problem of how you're going to move your mountain of mass.

[Molyneux]

I don't know what the other end of a black hole looks like...but it sounds a whole lot like "SQUISH".