Politics: Barack Obama's apparent choice for Energy secretary is physicist Steven Chu. While there's no question about Chu's brilliance, his political activism is not what the country needs.Chu is a Nobel Prize winner. He's also a tree sitter. Not the kind who literally goes out on a limb in a childish fit of civil disobedience in order to stop loggers or developers from cutting down a tree. But Chu did plop himself on a California buckeye tree last year to pose for a photo for Vanity Fair's special "green" issue. The tree could be passed off as a meaningless prop...