When will the Sun destroy the Earth? How do plagues spread? Those are only two of the cheerful questions asked and answered by Mary and John Gribbin in Big Numbers, their latest buoyant compilation of brief explanations of mathematical and scientific ideas. Sometimes, the scale of thinking is literally universal, as we contemplate the size of infinity or the distance to remote galaxies. Elsewhere, it is infinitesimal, directing us to sub-atomic theories. There are many dimensions in between, featuring bacteria, cells, computers and planets, all clearly expounded in lively child-friendly prose. Big Numbers costs Pounds 4.99 from Wizard Books.