Last April I posted about how the earth had improved since the first Earth Day. At the end of the post is a poll about whether, after reading the post, the reader was optimistic, pessimistic, or ambivalent about the future. Overwhelmingly, people were (and apparently, are) pessimistic about the future of the earth. Matt Ridley, a former science writer for the Economist, has written a book, The Rational Optimist, saying that this overwrought litany of doom is misplaced because our ideas “have sex.”