The technologists claim that if everything works [in a nuclear fission reactor] according to their blueprints, fission energy will be a safe and very attractive solution to the energy needs of the world. ... The real issue is whether their blueprints will work in the real world and not only in a "technological paradise."... Opponents of fission energy point out a number of differences between the real world and the "technological paradise." ... No acts of God can be permitted.