Billy Brown wrote:
>
>
> 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.
Lessee, you can make a 10 kiloton weapon these days to fit in a suitcase, lets say, generously that that suitcase still weighs in at 100 kilos., so 100 kilogram devices can produce 10 million kilograms of TNT levels of explosive power. A ratio of 100,000 to 1. If a microgram nuke device is proportionate in capability, if there is not a steep falloff in capability, then it should produce the equivalent of 100 grams of TNT of explosive force. This is far from a trivial amount if a robotic bug can deliver it into your eardrum.....its equal to a good fraction of a stick of dynamite blowing up in your ear.... Whatever is left gets fried from radiation...
Mike Lorrey