In 2007 the leading online forum for scientists and thinkers, www.edge.org, issued its third annual question: 'What are you optimistic about, and why?' As with its predecessors -- 'What do you believe to be true but cannot prove?' and 'What is your dangerous idea?' -- the question created an instant media storm, with global reaction to the answers posted by some of the world's most eminent scientists and thinkers. WHAT ARE YOU OPTIMISTIC ABOUT is the third collection of answers to the Edge question. Featuring responses from Richard Dawkins, Brian Eno, Steven Pinker, Sir Martin Rees and Matt Ridley, and covering topics as diverse as the decline of violence, the path to enlightenment and mankind's enduring ability to solve problems, this collection is guaranteed to make you look on the bright side. Global warming, the war on terror and rampant consumerism getting you down? Lighten up! And read some of the world's brightest brains on their reasons to be cheerful.