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Bragging rights: celebrating the centenary of crystallography

Lawrence Bragg’s work in crystallography changed the way we see the world. orinoco14

Bragging rights: celebrating the centenary of crystallography

Lawrence Bragg’s work in crystallography changed the way we see the world. orinoco14

In April this year, media coverage of the 100th anniversary of the 1912 sinking of the Titanic blanketed the airwaves in Australia. But this year marks another centenary, one that has had a much deeper and longer-lasting impact – one that literally changed the way we view the world.

It also has more direct relevance to Australia, though it’s hardly rated a mention in our media: the centenary of crystallography.

Sorry, what’s crystallography?

As defined by the International Union of Crystallography, crystallography is “the branch of science devoted to the study of molecular and crystalline structure and properties, with far-reaching applications in mineralogy, chemistry, physics, mathematics, biology and materials science”.

Crystals of the substance being studied are prepared and then irradiated with X-rays. The resulting diffraction pattern is measured and interpreted, using Bragg’s Law and other mathematical formulae, to generate an electron density map of the crystal contents.

Insulin crystals. Wikimedia

The map reveals the structure of the atoms forming the crystal, and both the map and the crystal structure can be visualised with high-end computer graphics software and hardware. Solving a new crystal structure and seeing it in 3D for the first time provides a thrill of discovery like no other.

Crystallography allows us to see our world at the level of the atom, by generating crystal structures that can be analysed and probed, and then used to design new and improved molecules.

The Braggs – of Bragg’s Law fame – used crystallography to explain how sodium and chloride together form salt crystals and how carbon atoms interact to form diamond crystals. Others have used crystallography to discover how some materials repel water, how plants harvest light, how antibodies recognise pathogens, and how aspirin eases inflammation and pain.

Sorry, who was Bragg?

In 1912 Lawrence Bragg, a young Australian working in Cambridge, made a key discovery that helped establish the field of crystallography. But we need to go back a few more decades to reveal the full and fascinating story of this brilliant Australian.

Lawrence Bragg in 1915 Wikimedia Commons

In 1886, Lawrence’s father William Bragg, an Englishman educated at Trinity College Cambridge, took up the Professorship in Mathematics and Theoretical Physics at the University of Adelaide. He was 24 years old.

In Adelaide, he met and married a young Australian woman, Gwendolin Todd. Gwendolin herself came from a distinguished family because her parents were Charles and Alice Todd. Charles Todd directed the establishment of the overland telegraph between Adelaide and Darwin, a massive infrastructure and engineering undertaking that was the information superhighway of its day.

When completed in 1872, messages that in the past would have taken months to reach their recipients arrived in just 24 hours. Not surprisingly, Charles and Alice Todd were well-loved and highly respected members of the Australian community: their names have been commemorated in the city of Alice Springs and the River Todd.

Sir William Henry Bragg Wikimedia Commons

Lawrence Bragg was born into an extraordinary family in 1890, the eldest of three children to William and Gwendolin. He was exceptionally bright, finishing high school at St Peter’s College Adelaide aged 14, and completing the equivalent of an Hons degree in science at Adelaide University in three years.

In 1908, his father William Bragg accepted the position of Chair of Physics at Leeds University, and the family moved with him in 1909 to the UK. Lawrence, aged 19, studied at Trinity College Cambridge for a second undergraduate degree in Natural Sciences. He graduated with first class honours in June 1912, aged 22.

At around the same time in Germany, physicist Max von Laue discovered that when X-rays were shone through a crystal of copper sulphate, the crystal acted like a grating and produced a diffraction pattern that could be measured on photographic film.

The crystal structure of table salt. Wikimedia

Max von Laue was awarded the 1914 Nobel Prize in Physics for this discovery. The significance of his work was that the diffraction pattern held the key to understanding the structure of the atoms forming the crystal. If the relationship between diffraction pattern and the atomic structure could be established, the secrets to the structure of matter would be revealed.

Lawrence Bragg discussed von Laue’s work with his father in the European summer of 1912. Back in Cambridge, he derived the formula that underpins the field of crystallography, and presented his findings at the November 1912 meeting of the Cambridge Philosophical Society.

Subsequently, he and his father applied the formula - now known as Bragg’s Law - to solve the first crystal structures, rock salt (sodium chloride), diamond, potassium chloride and many others.

War and turmoil

In 1914 war broke out in Europe and scientific research was halted. In August 1915, Lawrence was posted to France where he developed sound ranging methods for pinpointing enemy artillery positions – work for which he was later awarded a military cross and an OBE.

Hemoglobin, alpha 1 Wikimedia

That same August, Lawrence’s younger brother Bob was posted to Gallipoli, where he died a few weeks later.

Barely two months after that, Lawrence - aged 25 - and his father William were awarded the 1915 Nobel Prize in Physics for their analysis of crystal structures. One can hardly imagine the emotions the family must have been going through at the time.

In 1938, Lawrence was appointed Cavendish Professor of Experimental Physics at Cambridge where he initiated studies on biological molecules.

He recruited Francis Harry Compton Crick and James Dewey Watson - later awarded the 1962 Nobel Prize in Physiology or Medicine for their discoveries relating to nucleic acids – and Max Ferdinand Perutz and John Cowdery Kendrew – awarded the 1962 Nobel Prize in Chemistry for determining the first protein crystal structures, those of haemoglobin and myoglobin.

Australia Post

In 1912, no-one could have imagined Lawrence’s discovery of Bragg’s Law and its application to crystal structure determination would one day lead to the structures of proteins, structure-based drug design and structural genomics, let alone to the crystal structures of challenging membrane proteins. Yet these are but a few of the many direct consequences of Bragg’s groundbreaking work a century ago.

Though few Australians know about this extraordinary man, our first Nobel Laureate, and the prize’s youngest ever recipient, momentum is building. A public symposium is planned in Adelaide for December this year. And before this, in August, Australia Post will release a series of five stamps honouring our early Nobel laureates. One of these – pictured above right – will feature Lawrence Bragg.

After reading this story, I hope you will be encouraged to buy Lawrence Bragg stamps and use them to send letters to all your friends and family so that you too can brag about Bragg.

Further reading:

William and Lawrence Bragg, Father and Son: the Most Extraordinary Collaboration in Science by John Jenkin, Oxford University Press, 2007.