Artificial Black Holes, and crazy amounts of renewable energy

[Remington]

Saw this on Digg today, and thought it was quite interesting.
http://io9.com/5391989/a-black-hole-engine-that-could-power-spaceships

Artificially generated black holes could provide us with the power to make inter-solar travel a possibility. New research shows how strapping a black hole to your starship might just give you the juice to get to Alpha Centauri.

Louis Crane and Shawn Westmoreland of Kansas State University propose a way to use black holes as fuel that is entirely within the bounds of physics and technology as we know them, but would take phenomenal amount of engineering.

The crux of their idea involves using using a laser to form a micro black hole, which could be used as an energy source. This would be a Schwarzschild, or non-rotating, black hole which outputs Hawking Radiation, and the smaller the black hole, the more energetic.

Of course, making a black hole isn't the world's most easy undertaking. It takes a huge amount of power to build one in the first place. To make one of these mini black holes, Crane and Westmoreland propose a 370km2 solar panel, at an orbit one million km from the surface of the sun, which, if perfectly efficient, would gather enough energy per year to make one black hole. This power would be fed to a spherically converging gamma laser, with a lasing mass of around 10^9 tonnes. However, after you make a few black holes, you can use them as a power source to make more.

According to the authors, a black hole to be used in space travel needs to meet five criteria:

   1. has a long enough lifespan to be useful,
   2. is powerful enough to accelerate itself up to a reasonable fraction of the speed of light in a reasonable amount of time,
   3. is small enough that we can access the energy to make it,
   4. is large enough that we can focus the energy to make it,
   5. has mass comparable to a starship.

Fortunately, black holes have a sweet spot in terms of size, power and lifespan which is almost ideal. If you take a trip to Alpha Centauri, with an acceleration of 1g to the half way point, and then decelerate at 1g for the remainder of the journey, the trip takes a relativistic 3.5 years. A black hole that would survive the entire trip would have a radius of 0.9 attometers, would have a mass of 606,000 tonnes, and a power output of 160 petawatts. The lifespan of the black hole could be extended by feeding it mass, too.

For longer trips, you could use larger but weaker holes, and smaller and more powerful ones for short trips.

Cool stuff, and it seems kinda plausible (from my limited understanding of physics). Could be a viable alternative once fusion proves insufficient... although I'm not quite sure how they plan to contain the thing.


Here's the report itself. The first two pages or so are pretty easy reading, then it breaks out the hardcore math.
http://arxiv.org/PS_cache/arxiv/pdf/0908/0908.1803v1.pdf

[Scribbly]

This is interesting...

I saw a documentary on the BBC this week which said that black holes are actually a point where our understanding of physics breaks down, because the centre of a black hole is a point where there is 'infinite' energy. The documentary was saying that we just don't understand practically anything at all about black holes, and they had a lot of scientists on it trying to explain that the theories we use to understand physics completely break down when applied to them.

I wonder how that ties in with this, because presumably these people are theorizing that they can measure the energy of black holes and come out with a number that ISN'T a sideways eight, or a recurring stream of sideways eights, which is what the documentary finished saying.

[Igor]

The physics breaks down inside the black hole. The area just outside it is understood pretty well. This idea seems to treat black holes as "black boxes" which basically give out energy. Which is true as far as anyone knows; Hawking Radiation is one of the few bits of quantum gravity that most people agree on.

The only problem I have with it (apart from the HUEG laser and solar panel) is that smaller black holes  -while giving off more energy-  "evaporate" faster. In fact, that's why they give off more energy. It seems difficult to power a spacecraft with something that has a small lifespan.
But then I read the article again and realised that they already took account of that. Yay! Free energy for everyone!

[Remington]

The physics breaks down inside the black hole. The area just outside it is understood pretty well. This idea seems to treat black holes as "black boxes" which basically give out energy. Which is true as far as anyone knows; Hawking Radiation is one of the few bits of quantum gravity that most people agree on.

The only problem I have with it (apart from the HUEG laser and solar panel) is that smaller black holes  -while giving off more energy-  "evaporate" faster. In fact, that's why they give off more energy. It seems difficult to power a spacecraft with something that has a small lifespan.
But then I read the article again and realised that they already took account of that. Yay! Free energy for everyone!

Apparently BHs are pretty efficient at converting matter to energy. Best of all, unlike nuclear fusion it really doesn't matter what you feed them.

[Chief Uwachiquen]

Apparently BHs are pretty efficient at converting matter to energy. Best of all, unlike nuclear fusion it really doesn't matter what you feed them.

This got me thinking and I may just be an idiot when I say this so feel free to shake the crime stick at me -but- if you can feed them just any old matter then it makes me wonder if we can't use it to cull the heaping landfills we've got to "burn" as a "fuel". Just a thought.

[Rumckle]

That'd work if we had it on land, such as a power generator on earth based on such a principle. For a space ship, that'd probably start in space (and we'd shuttle up to it) it may be too expensive. Though, in that case a lot of space junk that is in orbit already could be used.

[Triple Zero]

But they're holes in space. You're basically burning up and sacrificing the geometry of our reality for energy. This can't be good.

Where's the catch. There shall be a catch.

And even if there's no catch, the catch will be that monkeys shouldn't be allowed to play with those amounts of energy.



About the trash, as soon as we can economically get our trash up there, shooting it in random directions into space works just as well. You don't really need a black hole. Space is pretty big. Just make sure it doesn't stick in our orbit.

[Rumckle]

But they're holes in space. You're basically burning up and sacrificing the geometry of our reality for energy. This can't be good.

Where's the catch. There shall be a catch.

And even if there's no catch, the catch will be that monkeys shouldn't be allowed to play with those amounts of energy.

Well, blackholes already exist, this would just be a synthetic one.

Plus the paper noted that you didn't have to feed them stuff, only if you want to increase their lifetimes.

[Chief Uwachiquen]

That'd work if we had it on land, such as a power generator on earth based on such a principle. For a space ship, that'd probably start in space (and we'd shuttle up to it) it may be too expensive. Though, in that case a lot of space junk that is in orbit already could be used.

Yeah, I wasn't too clear on my thinking. I was meaning if we were to use it for some sort of energy down on the earth. If it pumped out as much energy as they're thinking it could power a large chunk of a city, maybe? Hell, I don't know. All I know is I'd pay handsomely* for someone to write on the apparatus that you used to feed the black hole "Mr. Fusion" A'La Back to the Future.

* Provided I actually had money.

[Triple Zero]

Plus the paper noted that you didn't have to feed them stuff, only if you want to increase their lifetimes.

Yeah but why does it have to be virgins? it always has to be virgins.

And don't get me started on what happens when you feed them after midnight...

[Remington]

That'd work if we had it on land, such as a power generator on earth based on such a principle. For a space ship, that'd probably start in space (and we'd shuttle up to it) it may be too expensive. Though, in that case a lot of space junk that is in orbit already could be used.

Yeah, I wasn't too clear on my thinking. I was meaning if we were to use it for some sort of energy down on the earth. If it pumped out as much energy as they're thinking it could power a large chunk of a city, maybe? Hell, I don't know. All I know is I'd pay handsomely* for someone to write on the apparatus that you used to feed the black hole "Mr. Fusion" A'La Back to the Future.

* Provided I actually had money.

Thefuck? A part of a city?

A black hole that would survive the entire trip would have a radius of 0.9 attometers, would have a mass of 606,000 tonnes, and a power output of 160 petawatts. The lifespan of the black hole could be extended by feeding it mass, too.

165 Petawatts. That's enough to power all of the civilizations on our entire planet 11,000 times over. That's about the same amount of energy as Earth's energy budget, for Erissakes. Also, I don't even want to go into how bad of an idea an earth-based one would be. The Hawking radiation those things throw out takes the form of gamma radiation, which has a well-deserved reputation for killing everything it touches. You probably don't want to be within several million miles of the thing when it finally detonates.

[Remington]

Plus the paper noted that you didn't have to feed them stuff, only if you want to increase their lifetimes.

Yeah but why does it have to be virgins? it always has to be virgins.

And don't get me started on what happens when you feed them after midnight...

We must appease it. If it says it prefers virginal atomic matter, then who are we to argue?

[Triple Zero]

We should feed it virgin kittens and virgin baby seals. I hear that pisses off those PETAwatts to no end.

[rong]

and extra virgin olive oil.

[Cain]

We could just burn accountants and bankers.  They created a giant black hole in our economy, so its basically the same thing.

Edit: burn academic economists, too.