How cats find their way back to their former homes, the science of self-winding watches, why sunlight triggers sneezes, the basis of lightning and does an open window deter a strike, how fast gravity propagates, is it better to turn off the hot water in the daytime and why do thunderstorms cause powercuts? Join Dr Chris for the answers in this week's brain-expanding episode of Ask! Like this podcast? Please help us by supporting the Naked Scientists