It's also good to have a number of these things in the oven, because it's hard to predict when a sudden discontinuous leap might make practical in the short ter

It's also good to have a number of these things in the oven, because it's hard to predict when a sudden discontinuous leap might make practical in the short term something that previously seemed like a multi-generational project. I presume almost no one in 1920 could have imagined that anything approaching the output of fission energy would become common in their lifetime.