Elon Musk wants to build a pneumatic tube transportation system capable of whisking people from San Francisco to Los Angeles in 30 minutes. (Xeni told you about this back in July.)
Technologically speaking, it's a perfectly possible thing to do, writes Tim Fernholtz at Quartz. The problem is the high cost of infrastructure development, something have everybody (whether they want to built a train, a highway, or a futuristic hyperloop) tends to underestimate. That's particularly a problem given the fact that whole idea behind Musk's hyperloop is that it could be a cheaper replacement for an expensive high-speed rail line already under development.
