"I’m going to assume (generously, I think) that the minimum size for a successful colony is 10 000. The only experience we have is the Apollo program, which transported 12 astronauts to the Moon (a distance of 1 light second) at a cost of $100 billion or so (current values). So, assuming linear scaling (again, very generously), that’s a cost of around $10 trillion per light-second for 10 000 people."My question is - how in the world is linear scaling of pricing "very generous"?!?!
Apollo was the first time we transported people to another world. We usually think that the cost of doing something highly complex like sending people to another world drops precipitously as it is done over and over again. It's called "learning by doing". The average cost savings from going from a moon program to an interstellar program are going to be tremendous (although of course you need to do some "doing" to get "learning by doing" between now and then!).
It seems highly ironic that the author of Zombie Economics is using increasing marginal costs assumptions to call linear cost projections "very generous" when I thought we moved past that sort of thinking in these cases many, many decades ago.
I'm not saying we should be working on an interstellar trip right now. We should be working on Mars, and just pay a few theoretical physicists to bend the cost curve on interstellar travel for the time being. But nobody - certainly no economist - should be under the misapprehension that learning by doing isn't going to apply in space exploration.