Doomsday warnings seem to come and go, but each time they are sounded we can't help but take heed. There is always a possibility that this time could be real. Ever since the Large Hadron Collider - Cern's record-breaking atom smasher began operations, many have voiced concerns over what would happen if the particle accelerator managed to inadvertently create a black hole here on Earth. In "The Future: Prospects for Humanity", Lord Rees has outlined several existential threats to our planet ranging from an asteroid strike to a super-advanced artificial intelligence. In one chapter, several doomsday scenarios involving the Large Hadron Collider are described. via Yahoo News: Earth could be reduced to a dense mass measuring just 330 feet across if particle accelerators set off a catastrophic chain of events, the astronomer royal has warned. In his latest book, On The Future: Prospects for Humanity, Prof Lord Martin Rees, outlines the existential threats facing the planet,