<p>Obvious questions do not always have obvious answers.<br><br>John Gribbin is known for giving us simple explanations of big concepts in science. But there is another way to probe the mysteries of the Universe and our place in it. Faced with persistent enquiries from his grandchildren, Gribbin realised that simple questions, such as 'Why is the sky blue?', sometimes require big answers, understandable in straightforward language.<br><...