11 September 2012 Last updated at 08:00 GMT China is the world's second biggest economy, its rising superpower, and is on the cusp of a once-in-a-decade leadership change, but the man expected to take over at the head of the Communist Party has vanished from view, and we don't know why. Is Xi Jinping sick? Has he had a mild heart attack? Did he hurt his back playing football or swimming? Is he extraordinarily busy preparing for the day, probably next month, when he will be elevated to take over from Hu Jintao as the head of China's Communist Party, or is there some more sinister power struggle happening? All have been suggested as explanations on China's buzzing social media sites. It has even been claimed he was injured in a car crash, which was maybe a plot against him. But that seems fanciful. However, nobody knows for certain because China's government is not saying, and that in itself is unsettling many. When Communist party figures disappear from view it sometimes sends a signal that they are in trouble. There is no evidence that is the case now but, without a simple explanation, rumours have been swirling and they have broken into the open..... full story: BBC News - Where is Xi Jinping?