Anyway, there's a crucial difference between "financially impossible" and "politically feasible." It's important to distinguish this because what's politically

Anyway, there's a crucial difference between "financially impossible" and "politically feasible." It's important to distinguish this because what's politically feasible can shift over time; it's not interesting to talk about whether we can agree to build a perpetual motion machine but it might be interesting to talk about whether we should send a manned mission to Mars.