Why do pinecones have two series of spirals made up of exactly eight or 13 scales? Why do sunflowers have two series of spirals of 21 and 34 petals respectively, or of 34 and 55, or more, depending on their width — and why are these pairs of figures always two consecutive numbers in a sequence of Fibonnaci numbers (obtained by a mathematical formula by which each term is found by adding the two terms immediately preceding)?
Why is the sky blue during the day and black at night? How are light particles, the atoms of solids, or the drops that make up liquids arranged in a strict order to produce such amazing results as laser, superconductivity or superfluidity?
Sébastien Balibar answers these and many more questions about our everyday environment in his own lively style, which always succeeds in making physics astonishing and fun.

Sébastien Balibar is a physicist and research director at the Centre National de la Recherche Scientifique (CNRS), in the laboratory for statistical physics of the Ecole Normal Supérieure. He was recently awarded the Fritz London Memorial Prize, the highest international award in his field. He is one of the contributors to Demain la physique, 2004.