Re: Not quite magic physics [was Re: Quantum Computers]

Doug Jones (
Sun, 22 Aug 1999 23:08:13 -0700

Eugene Leitl wrote:
> Speculations of manufacturing miniature black holes by focusing the
> output of e.g. Dyson sphere lasers on a small region of space have
> been discussed here before.
> Iirc Sol is losing about 2 MT/s mass (though probably mostly to
> protons which go out as solar wind).

Not protons, photons- 1 AU is 150E6 km = 1.5E11 m, sunlight is 1350 W/m2 at earth, so total power out = 4piR^2(1350) = 3.8E26 W. E=MC^2, so

P = MdotC^2 and Mdot = P/C^2 = 4.2E9 kg/s = 4.2 MT/s

Four million tonnes of energy per second is one hell of a lot of power. Current total human power usage is around 10 terawatts, give or take an order of magnitude... or about 0.01 g/s.

Total insolation on Earth is about 1.7E17 W, or about 1.9 kg/s.

Four million tonnes of energy per second is one HELL of a lot of power.

With a really *big* chirped diffraction grating (tens of lightseconds on a side) you could create attosecond pulses with megatonne mass. Colliding these pulses[*] should create tidy little black holes. It may require hundreds or thousands of seconds of the sun's output to make black holes that have evaporative lifetimes of at least a few years, so that they can be trapped and used. The energy in the beams must all reach the target volume in less time than it takes for a photon to traverse the "width" of the hole. Yoctosecond timing?

About the best use of black holes is the fact that they don't conserve baryon number, so you can turn any old mass (even iron) into energy. The very high temperature of a black hole would allow very high carnot efficiency.

Doug Jones, Freelance Rocket Plumber
[*] to avoid the circular firing squad's dilemma, more than two beams are
needed so that missed pulses don't fry the opposite launch optics. Four
beams originating at the corners of a tetrahedron should work... but more
would produce a smoother implosion.  Asymmetries in the implosion will
cause the resultant hole the shoot off in the opposite direction.  Thus two
beams meeting at right angles could create a hole shooting off at .7 c