Scientific Modelling and Make-Believe

Models are crucial to the scientific endeavour because many investigations are carried out on models rather than on reality itself: we can learn about the motion of planets, the dynamics of populations and the growth of an economy by studying their respective models. Some models are material objects. The aerodynamic properties of a car are investigated by putting a scale model in a wind tunnel; the spatial structure of molecule can be understood by looking at a ball-and-stick model of it; features of cell division are explored through model organisms like worm Caenorhabditis elegans; and the reaction of an economy to tax increases can be studied by observing how water flows through a tailor-made system of pipes and reservoirs.