The world of tomorrow holds many new dangers that will threaten our lives: population explosion will stretch our natural resources, creating food and water shortages on a global scale; terrorism will reach new levels that will test our security systems like never before; and even technology designed to help us could end up hurting us, when machines reach human intelligence levels and begin to think for themselves. From robot revolutions to asteroid attacks, we'll need a whole new arsenal of smart tools and strategies to battle these deadly threats. Technology is already evolving to address our most terrifying future fears.