Why Elon Musk is wrong about nanotechnology

You might expect Elon Musk, the business magnate, engineer and serial entrepreneur would be a fan of all things techy. After all, his radical enterprises are built on pushing science to its limit. He's behind a raft of visionary projects ranging from Tesla's driverless electric cars and SpaceX's self-landing reusable rockets to plans for 1,000kph "hyperloop" trains. But it appears there is a size limit to Musk's technophilia. He recently tweeted that he thinks nanotechnology is "BS".