'You either have nasty physics and nice mathematics, or nice physics and nasty mathematics.' [1]'These results of course showed the immensely greater power of the spectrometer for analysing crystals. I was very much teased at the time for upsetting my father's theory! But you will see how much my father's work at Leeds, and mine at Cambridge, were interwoven at that early time ...' [2]
William Lawrence Bragg was born in Adelaide, South Australia, in 1890. He was the eldest child of William Henry and Gwendoline Bragg. He had a brother, Bob, who was one year younger than him, and a sister Gwendolen who was seventeen years his junior.
'Billy' was a dreamy, quiet child, preferring solitary pursuits such as shell collecting, which he did on family holidays at the sea side. He even discovered a new cuttlefish, which was named Sepia Braggii after him. Academically, Lawrence was always ahead of his age group at school, yet was not very good at games and social activities. He once said to his sister Gwendolen: 'You and I find things easier than people, Gwendy.' [3]
Lawrence was only fifteen years old when he commenced study at the University of Adelaide, and he graduated with a first-class honours degree in mathematics in 1908 .
In 1909, Lawrence travelled to England to study at Cambridge University. This move coincided with the family's move to Leeds, England. He entered Trinity College, intending to become a mathematician. However, during his second year, his father, William, encouraged him to change his focus to physics.
Lawrence graduated from Cambridge University with first class honours in 1912. After finishing his studies, he stayed on to work at the Cavendish Laboratory, Cambridge University. At this time there was a long-standing debate going on over the nature of x-rays: were they waves or particles?
Over the 1912 summer, Lawrence had many conversations about x-rays and crystals with his father, William Bragg. In the autumn, he began investigating van Laue x-ray patterns, which led to a sudden and brilliant inspiration which solved the riddle. Lawrence identified that x-rays were explained in part as waves, and also as particles, and from this insight he developed Bragg's Law. He published his first paper on the subject in November 1912.
The mutual scientific interest Lawrence and his father shared was very enjoyable for both of them. Over the next two years they collaborated in the study of crystal structure using x-rays, and published a joint book X Rays and Crystal Structure in 1915.
Together the Braggs showed that crystals of such substances as Sodium Chloride (NaCl or common salt) contain no actual molecules of NaCl, but simply Sodium ion and Chloride ion arranged in geometric regularity. This discovery revolutionised theoretical chemistry. Lawrence would analyse the arrangements of atoms within the crystals, while his father designed an x-ray spectrometer, and further explored x-ray radiation. Together they created the new science of x-ray crystallography. This was a most exciting and wonderful time for them both: 'like looking for gold and finding nuggets lying around everywhere.' [4] This work jointly earned Lawrence Bragg and his father, William, the Nobel Prize for Physics in 1915, 'for their services in the analysis of crystal structure by means of X-rays'. At twenty-five years old, Lawrence Bragg was the youngest ever Nobel Laureate.
The First World War saw Lawrence serving as Technical Advisor on Sound Ranging at the Map Section, General HQ France. During the war, his younger brother, Bob, was killed in action. Lawrence heard about his Nobel Prize while on duty in France.
Unfortunately some difficulties arose between Lawrence and his father when the general public did not directly credit Lawrence with his contributions to their discoveries. Lawrence desperately wanted to make his own name in research, but he felt the triumph of their discoveries passing to his father, as the senior man. William tried his best to remedy the situation, always pointing out which aspects of their work were his son's ideas; however, much of their work was in the form of joint papers, which made the situation more difficult. Sadly, they never discussed the problems, and the trouble lingered for many years.
After the war the close collaboration between father and son ended, but it was natural that their work would continue to overlap. They decided to divide up the available work, and agreed to stick to separate areas of x-ray crystallography. Lawrence was to focus on inorganic compounds, metals and silicates; William was to focus on organic compounds.
In 1919 Lawrence was made Langworthy Professor of Physics at the Victoria University, Manchester, where he remained until 1937. He married Alice Grace Hopkinson in 1921 and they had four children: Stephen, David, Margaret and Patience. Stephen became the third generation of Braggs to study mathemetics at Cambridge University.
In later years Lawrence turned his research focus to other fields, 'especially where his keen perception of geometric relations could stimulate progress'. [5] He was interested in the structure of silicates, silicate chemistry, metallurgy, and especially protein chemistry. In 1954 Lawrence established an independent team of researchers at the Royal Institution to study protein problems and undertake x-ray analysis of the structure of protein molecules.
An excellent lecturer and efficient organiser, Lawrence was well-liked and respected in his field. After the Second World War he helped organise the International Union of Crystallography, and was its Inaugural President. Like his father, Lawrence was concerned with science education and regularly gave lectures for children at the Royal Institution.
Lawrence Bragg was also Director, National Physical Laboratory, Teddington 1937-38; Cavendish Professor of Experimental Physics, Cambridge 1938-54; and Director of the Royal Institution, 1954-66. He was knighted in 1941 and made a Companion of Honour 1967. He was awarded the Hughes, Royal and Copley Medals, Royal Society of London.
Lawrence Bragg died in 1971, aged 81.
[1]
Caroe, G.M. [Lawrence Bragg's sister/William Bragg's daughter], William Henry Bragg, 1862-1942: man and scientist, Cambridge University Press, 1978, p. 70.
[2]
Ibid., p. 191.
[3]
Ibid., p. 39.
[4]
Ibid., p. 75.
[5]
Weber, Robert L., Pioneers of Science: Nobel Prize winners in physics, Institute of Physics, 1980, p. 55.
