[tesseractive]

Suppose we set a goal to build a dirigible the size of a small town that could float up in the air and people could live on it and it would have an expected lifespan of at least 30 years? It would be enormously expensive and I have little doubt that some new technologies would have to be pioneered to produce something so audacious. But at the end of the day, it's still reasonable to ask why that's a goal we should spend so much to achieve, and the fact that we would invent a bunch of cool technology along the way seems insufficient as a response. There are lots and lots of things that we could spend tons of money on that would produce a bunch of spin-off technology -- how would we decide which of these things we should dump truckloads of money into, and which ones we shouldn't?