I quote myself: >A few plausible ways around the problem (requiring extensions >of physics, however) come to mind: > > 2. Discover some ultra-cheap source of energy > (cold fusion?). Note that 1 cubic mile of (sea) water contains enough deuterium to provide about 5,400 USEs from the fusion reaction(s)-- D + D + D --> He4 + n + p + 21.6 MeV . Rex