William Lawrence Bragg

Sir William Lawrence Bragg CH, FRS, (31 March 1890 – 1 July 1971) was an Australian physicist who shared the Nobel Prize in Physics in 1915 with his father Sir William Henry Bragg. He was the director of the Cavendish Laboratory, Cambridge when the epochal discovery of the structure of DNA was made by James Watson and Francis Crick in February 1953.

Biography
Bragg was born in North Adelaide, South Australia. He was an impressionable boy and showed an early interest in science and mathematics. His father, William Henry Bragg, was Professor of Mathematics and Physics at the University of Adelaide. Shortly after starting school aged 5, William Lawrence Bragg fell from his tricycle and broke his arm. His father had recently read about Röntgen's experiments in Europe and used the newly discovered X-rays to examine the broken arm. This is the first recorded surgical use of X-rays in Australia.

Bragg was a very able student. After beginning his studies at St Peter's College, in 1904 he went to the University of Adelaide at age 14 to study mathematics, chemistry and physics, graduating in 1908. In the same year his father accepted a job at the University of Leeds, and brought the family back to England. Bragg entered Trinity College, Cambridge in the autumn of 1909 and received a major scholarship in mathematics, despite taking the exam while in bed with pneumonia. After initially excelling in mathematics, he transferred to the physics course in the later years of his studies, and graduated in 1911.

Bragg is most famous for his law on the diffraction of X-rays by crystals. Bragg's law makes it possible to calculate the positions of the atoms within a crystal from the way in which an X-ray beam is diffracted by the crystal lattice. He made this discovery in 1912, during his first year as a research student in Cambridge. He discussed his ideas with his father, who developed the X-ray spectrometer in Leeds. This tool allowed many different types of crystals to be analysed. The collaboration between father and son led many people to believe that the father had initiated the research, a fact that upset the son.

Bragg's research work was interrupted by both World War I and World War II. During both wars he worked on sound ranging methods for locating enemy guns, in this work he was aided by William Sansome Tucker. In autumn 1915 his brother was killed at Gallipoli. At about the same time, William Lawrence Bragg received the news that he received the Nobel Prize in Physics, aged 25, making him the youngest ever winner of a Nobel Prize. Between the wars, from 1919 to 1937, he worked at the Victoria University of Manchester as Langworthy Professor of Physics. He married Alice Hopkinson in 1921. He was knighted in 1941.

After World War II, he returned to Cambridge, splitting the Cavendish Laboratory into research groups. He believed that 'the ideal research unit is one of six to twelve scientists and a few assistants'. In 1948 Bragg became interested in the structure of proteins and was partly responsible for creating a group that used physics to solve biological problems. He played a major part in the 1953 discovery of the structure of DNA, in that he provided support to Francis Crick and James D. Watson who worked under his aegis at the Cavendish. Bragg was gratified to see that the X-ray method that he developed forty years before was at the heart of this profound insight into the nature of life itself. At the same time at the Cavendish Max Perutz was also doing his Nobel Prize winning work on the structure of haemoglobin. Bragg subsequently successfully lobbied for and nominated Crick, Watson and Maurice Wilkins for the 1962 Nobel Prize in Physiology or Medicine; Wilkins' share recognised the contribution made by researchers (using X-ray crystallography) at King's College London to the determination of the structure of DNA.

In April 1953 Bragg accepted the job of Resident Professor (Fullerian Professor of Chemistry) at the Royal Institution in London. He proposed that the Royal Institution should perform some form of public service, and suggested a series of lectures to show experiments to schoolchildren. This idea was met with an enthusiastic response, and by 1965 20,000 schoolchildren were attending these lectures each year. He worked at the Royal Institution until his retirement in September 1966.

William Lawrence Bragg's hobbies included painting, literature and a life-long interest in gardening. When he moved to London, he missed having a garden and so worked as a part-time gardener, unrecognised by his employer, until a guest at the house expressed surprise at seeing him there.

Bragg received both the Copley Medal and the Royal Medal of the Royal Society, and in 1967 was made a Companion of Honour by the Queen. He died at a hospital near his home at Waldringfield on 1 July 1971.

Since 1992 the Australian Institute of Physics has awarded the Bragg Gold Medal for Excellence in Physics to commemorate Sir Lawrence Bragg (in front on the medal) and his father Sir William Bragg for the best PhD thesis by a student at an Australian university.

Timeline

 * Victoria University of Manchester (1919–37)
 * Cambridge University (1938–53)

Prizes

 * Nobel Prize (1915)
 * Matteucci Medal (1915)
 * Hughes Medal (1931)
 * Royal Medal (1946)
 * Copley Medal (1966)

Family

 * spouse = Alice Hopkinson (m. 1921)
 * children = Stephen Lawrence, David William, Margaret Alice, Patience Mary