[ExI] Double-Earth (Was: kepler study says 8.8e9 earthlike planets)

[Eugen Leitl]

On Wed, Nov 27, 2013 at 12:42:00PM +0000, Anders Sandberg wrote:
> On 2013-11-27 07:26, Eugen Leitl wrote:
> >If yield is effectively infinite you no longer can make
> >assumptions about optimal placement, and just watch the hotspots.
> 
> Shovelling lithium deuteride is not that easy. The bottlenecks have

Lithium deuteride is easy to make, and even Li-6 enrichment is
a simple wet (COLEX) process. I've worked with lithium hydride,
not difficult at all.

> always been getting access to isotopes (and to some extent high

The actual bottleneck is availability of fissible for the primary.
HEU might be hard to get, but Pu by PUREX is easy in the age
of industrial automation, and really old nuclear waste. Reactor-grade
Pu merely lowers the yield.

> precision explosive control), never access to optimal placement.

Placement is everything if you dial up to 300 kT vs 3 kT.
 
> Still, even if you have a ridiculous amount of fusable material
> thinking about where to put the charge matters. You cannot easily
> make up for distance to the target by upping the yield. (You need to
> quadruple your power to go twice as far, roughly speaking)

Look at Manhattan in Google Earth while thinking about being really
yield-constrained. Than dial up to 300 kT. See the difference
in ground zero placement sensitivity? You can watch a few penthouses,
you can't watch everything.