Kind of cheap to quote from the first item in the article, but: While it could cost $10+ billion to build [...] scientists believe that carbon nanotube materia

Kind of cheap to quote from the first item in the article, but: While it could cost $10+ billion to build [...] scientists believe that carbon nanotube material could be the answer. Yeah, that's going to cost a lot more than $10 billion! There's plenty of fun tech and mega-structures in this book but I don't think it has anything interesting to say about the plausibility of any of it.