Questions no one knows the answers to. Larry Smith: Why you will fail to have a great career. Derek Sivers: Keep your goals to yourself. Reggie Watts disorients you in the most entertaining way. Nathan Wolfe: What's left to explore? Michael McDaniel: Cheap, effective shelter for disaster relief. Tali Sharot: The optimism bias. Carl Schoonover: How to look inside the brain. David MacKay: A reality check on renewables. William Noel: Revealing the lost codex of Archimedes. Jonathan Foley: The other inconvenient truth. Rory Sutherland: Perspective is everything.