Black Hole Spewing Energy

dragoness.ai points to this story at space.com about some exciting news for black hole enthusiasts, writing "The scientists had a chance for the first time in history to observe energy coming out of a black hole."

Comments

Advanced civilizations

[PD]

Some people have theorized that advanced civilizations might use black holes as a power source. Technological civilizations are always looking for something hotter to run their toys off of, and few things make as much heat as a massive black hole. Getting energy out of that much heat is easy, except for the problem of the huge gravity gradient and materials that can stand the temperature.

Re:Advanced civilizations

[coyote-san]

You have that backwards - smaller black holes have a steeper gravity gradient near the event horizon and they emit "hotter" radiation.

But I thought that the real way an advanced civilization would use black holes to produce energy involved putting a matter stream into the "ergosphere," to transfer some of its rotational energy to the matter stream.

original NASA press release

[rakerman]

The original NASA science news release has way cooler video and audio about the black hole.

Re:Hawking

[Yazeran]

You are absolutely right, but Hawking radiation cannot transfer huge energies over short time. The effect of Hawking radiation is also scales inversely with the mass of the black hole, as the gravitational gradient is steeper near a small black hole than near a big one.

Comparing Hawking radiation and this new magnetically induced energy transfer (if it exsists) is like comparing a candle light to the sun, Both create light but with different effect.

Having discovered this method of energy transfer in the space close to a black hole might also be the key to explaining the huge energy jets observed from the centers of some galaxies (This is also mentioned in the original NASA article).

Yours Yazeran

Plan: To go to Mars one day with a hammer.

Re:Hawking

[krlynch]

Except for Hawking radiation

Actually, no. The quote was: "Never before have we seen energy extracted from a black hole". Since we have never seen the Hawking radiation emitted by any known black hole, this statement is true (we've also never seen energy extraction occur by the Penrose process); the Hawking temperature of any black hole currently observable would be lower than the cosmic background radiation temperature, and certainly orders of magnitude below the black hole's local thermal environment, that we would never have a prayer to observe the HR.

OK, what's the coupling mechanism?

[Max Hyre]

My dilettante's knowledge of black holes says nothing comes out except some radiation whose name I forget, but which is generated by the simple expedient of having a pair of virtual particles generated near the event horizon, and one falls in while the other doesn't. Since the two can't then recombine to disappear, we get a spontaneously-generated random particle.

(This is why one commentator maintains that causality fails near the event horizon. You could just as well get a desk [or a sperm whale] show up as some alpha particles. Of course, this is very roughly of the same probability as all the air molecules in your cube all moving to the left half for a second, leaving you in a vacuum. I wouldn't worry about it myself.)

Anyway, since photons don't get out of a black hole, how is the alleged magnetism applied from within the dingus? Do space-time geodesics extend across the event horizon? (You know, all those neat graph lines in the diagrams showing how gravity warps space.) Does the spinning hole then drag them around, making it all work?

I'd appreciate it if Carl Sagan's successor would speak up on this subject; thanks.