From: Billy Brown (bbrown@conemsco.com)
Date: Mon Jan 25 1999 - 11:47:20 MST
mark@unicorn.com wrote:
> I was talking about nuclear energy in the more general sense;
> not neccesarily controlled use. Personally I find the idea of a mosquito
> flying through my window carrying a multi-ton-yield fusion bomb rather
more
> scary than a nanobot running off a miniature nuclear reactor. People had
> previously assumed that any hostile nanobot would be limited to chemical
energy
> levels rather than nuclear..
Ah. I see your point.
I think, however, that we are still safe. There are some formidable
problems with nano-scale (or even micro-scale) nuclear devices, and they
seem to be more a matter of fundamental physics than simple engineering
constrains.
First, there is a size requirement for the fuel. A fusion reaction releases
most of its energy in the form of hard x-rays, which are then absorbed by
the rest of the fuel, which produces the heat that sustains the chain
reaction. If you make the device too small the x-rays aren't captured, and
you can't produce a chain reaction. Even with nanotech, its hard to see how
you could make a device less than a few inches in diameter without this
problem being fatal.
Second, there is a power storage problem. Current bomb designs use a small
fission bomb to produce the energy that starts their fusion reaction. A
laser ignition system would need a similar amount of power, but it has to
get it from a non-nuclear source. That means you need a capacitor system
much bigger than the bomb itself - and we've already seen that the bomb has
a minimum size.
Third, as you noted, there is a diminishing yield problem. Even nuclear
weapons only produce so much bang per pound, and if you start measuring the
bomb size in micrograms it gets pretty puny. A robot mosquito might carry
as much punch as a truck bomb, if you could make a bomb that small - but
that's no big deal with reasonably advanced nanotech. Anything much smaller
than that won't even produce an explosion - it will simply produce a flash
of radiation when it detonates.
Billy Brown, MCSE+I
bbrown@conemsco.com
This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 15:02:55 MST