Observer: In his recent book Ten Billion, Stephen Emmott posed an intriguing question: what would happen if humanity discovered tomorrow that there was an asteroid on a collision course with Earth, one that would bring calamity on a precise date several decades in the future? An event like that could result in the eradication of a large chunk of life on Earth and would surely galvanise the planet, argued Emmott. Every scientist, engineer, university and business leader would be enlisted to find ways to deflect...