The Most Beautiful Experiment in Physics

There is often much debate in scientific circles as to which experiments or lecture-demonstrations are the most instructive, or spectacular. This chapter deals with several candidates, several of them having been carried out at the RI. One of these is the so-called two-slit experiment performed by Thomas Young in 1801. Others include the experiments and insights of Sir Lawrence Bragg, in connection with his interpretation of X-ray diffraction; Humphry Davy’s lecture-demonstration of the reality of the decrease of resistance of a metallic wire when its temperature is decreased. There is also a candidate from pre-Christian times, namely the determination of the circumference of the Earth done by Eratosthenes in Alexandria in the second century BC.