YouTube has had quite a year. Today it announced that all told, the site saw more than one trillion playbacks in 2011. Awful videos are, of course, ubiquitous on YouTube (the #1 video on the site for the year that didn't come from a major music label was Rebecca Black's "Friday"), but the most-watched science videos of 2011 are, as you can see below, awesome.
Colorado is now well into its first year as the first state to legalize recreational marijuana. How's it going? James Hamblin visits Aspen.