Introduction

‘The principle of science, the definition almost, is the following:The test of all knowledge is experiment. Experiment is thesole judge of scientific “truth”’.

So wrote Richard Feynman, famous scientist and Nobel Prize winner, noted for hiscontributions to physics.

It is possible that when Feynman wrote these words he had in mind elaborateexperiments devised to reveal the‘secrets of the Universe’, suchas those involving the creation of new particles during high energy collisionsin particle accelerators or others to determine the structure of DNA.Experimentation encompasses an enormous range of more humble (but extremelyimportant) activities such as testing the temperature of a baby's bathwater by immersing an elbow into the water, or pressing on a bicycle tyre toestablish whether it needs inflating. The absence of numerical measures ofquantities distinguishes these experiments from those normally performed byscientists.