LOS ANGELES (AP) — The concept sounds like something from the comic books that billionaire entrepreneur Elon Musk read religiously as a boy: a capsule that speeds along as fast as sound, carrying people between major cities, never troubled by bad weather or turbulence. "Short of figuring out real teleportation, which would of course be awesome (someone please do this), the only option for super fast travel is to build a tube over or under the ground that contains a special environment," Musk wrote in his proposal, which was posted online at http://www.spacex.com/hyperloop . In a written statement, California High-Speed Rail Authority Chairman Dan Richard suggested that Musk was oversimplifying the challenges. "If and when Mr.