the ultimate battery

Just how densely can you pack energy in a recoverable and portable form? Really, really dense. No, I'm not talking "Mr. Fusion" (a la "Back To The Future" fusion blender). Think "black hole" instead.

There was a flap in the news last year about the new super collider producing black holes. When they're small, though, black holes are supposed to evaporate faster than they expand. As they evaporate, they release energy. This is the radiation that made Hawking famous. So what if you were able to harness that radiation for useful purpose? Somebody did the calculations. :)

"Using the formulae from the section above, we find that a black hole with a radius of a few attometers at least roughly meets the list of criteria (see Appendix). Such BHs would have mass of the order of 1,000,000 tonnes, and lifetimes ranging from decades to centuries. A high-efficiency square solar panel a few hundred km on each side, in a circular orbit about the sun at a distance of 1,000,000 km, would absorb enough energy in a year to produce one such BH."
- http://arxiv.org/pdf/0908.1803v1

In other words:

1. Build a massive solar cell array in space.
2. Collect the charge for a long time, a year or more.
3. Discharge the energy in one enormous flash through a sphere of gamma ray lasers.
4. Their beams converge at a single point to produce a small black hole with the mass of a million tons. (The reverse usage of the E=mc² reaction that produces nuclear bomb explosions.)
5. Transport the black hole to your starship.
6. Siphon the evaporation energy until the black hole finally disappears.
7. Alternatively, feed it mass to restore its potential energy.
8. Repeat as needed.

Their paper goes on to discuss the feasibility of producing the black hole, of producing the starship drive, of harnessing the black hole in a power plant, etc. Besides finding it feasible, they think it could surely be improved.

"A BH with a life span on the order of a century would emit enough energy to accelerate itself to relativistic velocity in a period of decades. If we could let it get smaller and hotter before feeding matter into it, we could get a better performance."

Moreover, they say that it's perfectly reasonable to think that other star-faring civilizations are already using such technology. Because this technology "would emit gravitational radiation at nuclear frequencies", they say that SETI projects should consider building new detectors that work in this range. We might be able to detect galactic neighbors already using such energy devices. (Once somebody on Earth builds any kind of gravity detector that works.)

I think the only appropriate word for it is:

WOW!