How far away are we from a world where drones deliver packages? If Amazon is to be believed, not far at all. Others are not so sure: technical progress past this point isn’t merely a matter of invention; it’s a matter of public safety. Paul Misener, Amazon’s vice-president of global public policy, told a congressional hearing recently that his company would be ready as soon as all the rules were in place – but Misener gave no hints as to what that would look like beyond joking with a congressman that there was a basket of fresh fruit on the way to his doorstep to demonstrate the technology’s viability. The Federal Aviation Authority (FAA) will finally have regulations governing the commercial use of unmanned aircraft by June 2016. But the technology has a long way to go before then and larger machines aren’t airway-legal at all yet – only drones up to 25kg will be covered and the FAA points out in the proposed rules that, if you’re going to crowd the skies with radio-controlled flying robots, they had better all be using different radio frequencies that nobody can jam or hijack. Professor Sajiv Singh of Carnegie Mellon University Robotics Institute, who runs a “critical cargo delivery” company called NearEarth, said that piloting a state-of-the-art drone was a little more like leaving it a trail of breadcrumbs: go to this altitude, perform this short