Black holes violate the laws of thermodynamics?

[Solus]

I was watching a show on NOVA the other day about giant black holes being in the center all galaxies and it got me thinking.

Wouldn’t the existence of a black hole violate the laws of thermodynamics? The thought crossed my mind that a black hole could be used to create energy. Since a black hole is a giant vacuum, I think a device could be created that would be able to harness that pulling power. So in essence that would be unlimited energy. Where have I gone wrong? Aside from the fact that it would take to tremendous technology to even dream of reaching a black hole.

I’m guessing it would be possible for a black holes to be used to violate the laws of thermodynamics because black holes are beyond physics; they are beyond the rules.But doesn't that also throw the laws of thermodynamics completely off track because it would be theoretically possible to violate them?

I must add I'm not one of those woo-woos who dreams of perpetual motion machines (I know JREF gets a lot of those). I'm wondering about this in a scientific sense.

[Schneibster]

Mmmmmm. No, the problem is, to use the gravitational energy, you have to enter the gravitational field- and the deeper you go, the more potential energy you lose. If you were right, we could get free energy from the Earth's gravitational field as well. You can't, because any way you try to get the energy back out of the gravity field you have to buck the gravity field to extract it, and when you do, the amount of energy you get at the top end is reduced by that much. For example, electrons in a wire would slow down, which would reduce the amperage at the output. For example, photons in any kind of transmitted-power setup would be redshifted by the gravity enough to reduce their energy just as much as was gained by whatever you did to generate them.

Can't be done. Interesting idea, though- I suggest you poke around and look up "Hawking radiation." Stephen Hawking solved the exactly opposite problem, which is that entropy could be dumped into a black hole and could never return; which is just as much a violation of the laws of thermodynamics as what you are proposing is.

[Foster Zygote]

Well, black holes have gravity just like any other mass. If you compressed our sun into a singularity it would still have the same gravity it does now. The planets would continue in their orbits unchanged. So any device that utilized the "pulling" force of a singularity would also work around any mass. The only difference would be the concentration of gravity as you got near to the singularity. Black holes do emit energy in a sense. As gas from a companion star spirals in toward the event horizon it accelerates so rapidly that it emits powerful bursts of X-ray radiation. But using that as a source of energy would be many orders of magnitude worse than using a hydrogen bomb to heat your microwave burrito. The place where physics gets all wonky is at the event horizon, and anything that goes in there ain't comin' out anytime soon.*

*Hawking has hypothesized that black holes may, in a sense, "evaporate" over time. But this would take a very very very very very very very very very very very very very very very very very very very very very very very long time.

[DanishDynamite]

Black holes don't violate any of the laws of physics that we have been able to work out. The only thing they violate, as far as I know, is my personal Law of Esthetics.

[Dark Jaguar]

You don't like the way they look or something? Personally I find the universe a lot livelier with super gravity demons floating around.

[DanishDynamite]

You don't like the way they look or something? Personally I find the universe a lot livelier with super gravity demons floating around.
I love the way they don't look! Such non-colors, such non-flamboyance, such....uh....anyone ever read The Emperor's New Clothes?

To get back for a moment to my Law of Esthetics, the only reason I have something against Black Holes is that they incorporate too many uses of Infinity.

I'm not against infinity as such. I find its use in mathematics to be absolutely wonderful, useful and essential.

But attributing a physical object with this attribute?

[Solus]

How stupid of me!:covereyes A black hole is nothing more than a lot of gravity. Who needs a black hole? The earth could be used just the same. I just visualized a black hole as a giant vaccum cleaner, I didn't think of it in terms of gravity.

I remember some science fiction book I read years ago by Arthur C Clark. The aliens gave a gift of a black hole on the moon to humans. The point was that it was an unlimited source of energy. That's probably where my silly idea came from.

[Solus]

But I get the last word, inside a black hole the laws of thermodynamics and physics are a moot point. Give me D in math highschool math teacher Hah!

1+2x=0 the answer past the event horizion = 1. I challenge anyone to disprove that ;).

Shoot, the burden of proof is on me!

[ponderingturtle]

I was watching a show on NOVA the other day about giant black holes being in the center all galaxies and it got me thinking.

Wouldn’t the existence of a black hole violate the laws of thermodynamics? The thought crossed my mind that a black hole could be used to create energy. Since a black hole is a giant vacuum, I think a device could be created that would be able to harness that pulling power. So in essence that would be unlimited energy. Where have I gone wrong? Aside from the fact that it would take to tremendous technology to even dream of reaching a black hole.

I’m guessing it would be possible for a black holes to be used to violate the laws of thermodynamics because black holes are beyond physics; they are beyond the rules.But doesn't that also throw the laws of thermodynamics completely off track because it would be theoretically possible to violate them?

I must add I'm not one of those woo-woos who dreams of perpetual motion machines (I know JREF gets a lot of those). I'm wondering about this in a scientific sense.

THis does nothing to thermo dynamics. Sure the acreation disc can emmit a significant percentage of the items rest mass as energy, but that is just things rolling down hill.

Also neutron stars can emite up to about 10% of in falling matters mass as energy becuase of the loss of gravitational potential.

[Foster Zygote]

How stupid of me!

Far from it. You asked a question and learned something. That's the opposite of stupid.

[Schneibster]

I agree with Foster.

AFA a black hole being a source of energy, there is a way to get energy out of a black hole, but there are two caveats. First, it will cost matter, so it's not free. Second, because you're putting matter into it, it gets bigger which eventually could turn out to be a problem, depending on where you are keeping it.

If you dump matter into a black hole, you can arrange things so that it doesn't just fall straight in- it orbits it a while first. Black holes make enormous tides, ultimately exerting forces that no material object we know of can resist. All objects therefore are eventually torn apart into atoms. When this happens, the atoms swirl around the black hole, bumping into one another, and experiencing friction. This heats them enough to turn them into plasma, by stripping off some electrons; it can heat the plasma enough that it will emit X rays or even gamma rays, and it also emits a lot of heat, light, and ultraviolet. You can use this output of energy. But it's not free, and you really wouldn't want to be very close to the black hole while all of this was going on; you'd be fried alive, or die of radiation sickness.

[Schneibster]

To get back for a moment to my Law of Esthetics, the only reason I have something against Black Holes is that they incorporate too many uses of Infinity.

I'm not against infinity as such. I find its use in mathematics to be absolutely wonderful, useful and essential.

But attributing a physical object with this attribute?Well, actually, astrophysicists don't think that there are any infinities involved. Most think that those infinities are relativity telling us that it can't describe what happens inside the hole; and since the inside of a black hole is inaccessible from our spacetime, there's not only no way to tell, but no need to know, other than curiosity. Nothing that happens inside the event horizon can ever affect anything outside the event horizon.

[DanishDynamite]

Well, actually, astrophysicists don't think that there are any infinities involved. Most think that those infinities are relativity telling us that it can't describe what happens inside the hole...
Contradicting yourself in two connected sentences? Is that a record? ;)

Seriously, I'm well aware that the last word has by no means been said regarding black holes. Hence the feverish search for a theory which incorporates general relativity and quantum theory.

My initial response on this thread was mostly a joke.