54 years ago today, July 1, 1971 (May 9, 1971 in the lunar calendar), British physicist William Lawrence Prague passed away. William Lawrence Bragg (March 31, 1890-July 1, 1971) was a British physicist. He and his father, William Henry Bragg, studied X-ray spectroscopy, proposed the theory of crystal diffraction, established the Bragg formula, and improved the X-ray spectrometer. The father and son jointly won the 1915 Nobel Prize in Physics. After Rutherford's death in 1937, Prague succeeded him as director of the Cavendish Laboratory. After taking office, Prague gave up the nuclear physics that the laboratory was originally good at, vigorously supported solid state physics, and encouraged the development of fringe disciplines such as biophysics and astrophysics, opening up new research directions for the laboratory. He is an honorary member of many groups in the UK, an honorary academician of the Academy of Sciences of the United States, France, Sweden, China, the Netherlands, Belgium and other countries, and an honorary member of the French Minerals and Crystallography Society. Received the Hughes Medal of the Royal Society, the Royal Medal, and the Roeblin Medal of the American Mineral Society. Lawrence Prague won the Nobel Prize when he was only 25 years old and is the youngest recipient of the Nobel Prize in Physics in history.