Wikipedia

Lawrence Bragg

This article is about the Australian-born physicist. For his father and fellow Nobel Prize winner, seeWilliam Henry Bragg.

Sir William Lawrence Bragg(31 March 1890 – 1 July 1971) was an Australian-born BritishphysicistandX-ray crystallographer,discoverer (1912) ofBragg's law of X-ray diffraction,which is basic for the determination ofcrystal structure.He was joint recipient (with his father,William Henry Bragg) of theNobel Prize in Physicsin 1915, "For their services in the analysis ofcrystal structureby means ofX-rays";[4]an important step in the development of X-ray crystallography.[5]

Sir
Lawrence Bragg
CHOBEMCFRS
Bragg in 1915
Born
William Lawrence Bragg

(1890-03-31)31 March 1890
Adelaide,Colony of South Australia
(nowSouth Australia,Australia)
Died1 July 1971(1971-07-01)(aged 81)
Waldringfield,Suffolk,England
EducationSt Peter's College, Adelaide
Alma materUniversity of Adelaide
Trinity College, Cambridge
Known forX-ray diffraction
X-ray spectroscopy
X-ray microscopy
Bubble raft
Bragg's law
Bragg–Gray cavity theory
Bragg–Williams approximation
Spouse
Alice Hopkinson
​
(m.1921)​
Parents
RelativesCharles Todd(grandfather)
Awards
Scientific career
FieldsPhysics
Institutions
Academic advisorsJ. J. Thomson
William Henry Bragg
Doctoral students
Other notable studentsWilliam Cochran
3rdDirector of NPL
In office
1937–1938
Preceded byFrank Edward Smith(Acting)
Succeeded byCharles Galton Darwin
Portrait of William Lawrence Bragg taken when he was around 40 years old.

Bragg wasknightedin 1941.[4]As of 2024, he is the youngest everNobel laureatein physics, having received the award at the age of 25.[6]Bragg was the director of theCavendish Laboratory,Cambridge, when the discovery of the structure of DNA was reported byJames D. WatsonandFrancis Crickin February 1953.

Biography

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Early years

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Bragg was born inAdelaide,South Australia toSir William Henry Bragg(1862–1942),[7]ElderProfessor of Mathematics and Physics at theUniversity of Adelaide,and Gwendoline (1869–1929), daughter ofSir Charles Todd,government astronomer of South Australia

In 1900, Bragg was a student atQueen's School, North Adelaide,followed by five years atSt Peter's College, Adelaide.He went to the University of Adelaide at the age of 16 to study mathematics, chemistry and physics, graduating in 1908. In the same year his father accepted the Cavendish chair of physics at theUniversity of Leeds,and brought the family to England. Bragg enteredTrinity College, Cambridgein the autumn of 1909 and received a major scholarship in mathematics, despite taking the exam while in bed withpneumonia.After initially excelling in mathematics, he transferred to the physics course in the later years of his studies, and graduated with first class honours in 1911. In 1914 Bragg was elected to a Fellowship at Trinity College – a Fellowship at a Cambridge college involves the submission and defence of a thesis.[8][9]

Among Bragg's other interests wasshell collecting;his personal collection amounted to specimens from some 500 species; all personally collected from South Australia. He discovered a new species ofcuttlefish–Sepia braggi,named for him byJoseph Verco.[10]

Career

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X-rays and the Bragg equation

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The composition of X-rays was unknown, his father argued that X-rays are streams of particles, others argued that they are waves.Max von Lauedirected an X-ray beam at a crystal in front of a photographic plate; alongside of the spot where the beam struck there were additional spots from deflected rays – hence X-rays are waves.[11]In 1912, as a first-year research student at Cambridge, W. L. Bragg, while strolling by the river, had the insight that crystals made from parallel sheets of atoms would not diffract X-ray beams that struck their surface at most angles because X-rays deflected by collisions with atoms would be out of phase, cancelling one another out. However, when the X-ray beam struck at an angle at which the distances it passed between atomic sheets in the crystal equalled the X-ray's wavelength then those deflected would be in phase and produce a spot on a nearby film. From this insight he wrote the simpleBragg equationthat relates the wavelength of the X-ray and the distance between atomic sheets in a simple crystal to the angles at which an impinging X-ray beam would be reflected.

His father built anapparatusin which a crystal could be rotated to precise angles while measuring the energy of reflections. This enabled father and son to measure the distances between the atomic sheets in a number of simple crystals. They calculated the spacing of the atoms from the weight of the crystal and theAvogadro constant,which enabled them to measure the wavelengths of the X-rays produced by different metallic targets in the X-ray tubes. W. H. Bragg reported their results at meetings and in a paper, giving credit to "his son" (unnamed) for the equation, but not as a co-author, which gave his son "some heartaches", which he never overcame.[12]

Work on sound ranging

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Bragg was commissioned early inWorld War Iin theRoyal Horse Artilleryas asecond lieutenantof theLeicestershire battery.[13]In 1915 he was seconded to theRoyal Engineersto develop a method to localise enemy artillery from the boom of their firing.[14][15]On 2 September 1915 his brother was killed during theGallipoli Campaign.[16]Shortly afterwards, he and his father were awarded theNobel Prizein Physics. He was 25 years old and remains the youngest science laureate. The problem withsound rangingwas that the heavy guns boomed at too low a frequency to be detected by a microphone. After months of frustrating failure he and his group devised a hot wire air wave detector that solved the problem. In this work he was aided byCharles Galton Darwin,William Sansome Tucker,Harold Roper Robinson,Edward Andrade[17]and Henry Harold Hemming. British sound ranging was very effective; there was a unit in every British Army and their system was adopted by the Americans when they entered the war. For his work during the war he was awarded theMilitary Cross[18]and appointedOfficer of the Order of the British Empire.[19]He was alsoMentioned in Despatcheson 16 June 1916, 4 January 1917 and 7 July 1919.[20][21][22]

Hot wire sound ranging was used inWorld War IIduring which he served as a civilian adviser.[23]

Between the wars, from 1919 to 1937, he worked at theVictoria University of ManchesterasLangworthy Professorof Physics. He became the director of theNational Physical Laboratoryin Teddington in 1937.[24]

After World War II, Bragg returned to Cambridge, splitting theCavendish Laboratoryinto research groups. He believed that "the ideal research unit is one of six to twelve scientists and a few assistants".

University of Manchester (1919–1937)

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When demobilised he returned to crystallography at Cambridge. They had agreed that father would study organic crystals, son would investigate inorganic compounds.[1][4]In 1919 whenErnest Rutherford,a long-time family friend, moved to Cambridge, Lawrence Bragg replaced him as Langworthy Professor of Physics at theVictoria University of Manchester.He recruited an excellent faculty, including former sound rangers, but he believed that his knowledge of physics was weak and he had no classroom experience. The students, many veterans, were critical and rowdy. He was deeply shaken but with family support he pulled himself together and prevailed. He and R. W. James measured the absolute energy of reflected X-rays, which validated a formula derived by C. G. Darwin before the war.[25]Now they could determine the number of electrons in the reflecting targets, and they were able to decipher the structures of more complicated crystals like silicates. It was still difficult: requiring repeated guessing and retrying. In the late 1920s they eased the analysis by usingFourier transformson the data.

In 1930, he became deeply disturbed while weighing a job offer from Imperial College, London. His family rallied around and he recovered his balance while they spent 1931 in Munich, where he did research.

National Physical Laboratory (1937–1938)

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He became director of theNational Physical Laboratoryin Teddington in 1937,[24]bringing some co-workers along. However, administration and committees took much of his time away from the workbench.

University of Cambridge (1938–1954)

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Rutherford died and the search committee named Lawrence Bragg as next in the line of theCavendish Professorswho direct theCavendish Laboratory.The Laboratory had an eminent history in atomic physics and some members were wary of a crystallographer, which Bragg surmounted by even-handed administration. He worked on improving the interpretation of diffraction patterns. In the small crystallography group was a refugee research student without a mentor:Max Perutz.He showed Bragg X-ray diffraction data fromhaemoglobin,which suggested that the structure of giant biological molecules might be deciphered. Bragg appointed Perutz as his research assistant and within a few months obtained additional support with a grant from theRockefeller Foundation.The work was suspended during the Second World War when Perutz was interned as anenemy alienand then worked in military research.

During the war the Cavendish offered a shortened graduate course which emphasised the electronics needed forradar.Bragg worked on the structure of metals and consulted on sonar and sound ranging, for which the Tucker microphone was still used. Bragg was knighted and became Sir Lawrence in 1941. After his father died in 1942, Bragg served for six months as Scientific Liaison Officer to Canada. He also organised periodic conferences on X-ray analysis, which was widely used inmilitary research.

After the war Bragg led in the formation of theInternational Union of Crystallographyand was elected its first president. He reorganised the Cavendish into units to reflect his conviction that "the ideal research unit is one of six to twelve scientists and a few assistants, helped by one or more first-class instrument mechanics and a workshop in which the general run of apparatus can be constructed."[26]Senior members of staff now had offices, telephones, and secretarial support. The scope of the department was enlarged with a new unit on radio astronomy. Bragg's own work focused on the structure of metals, using both X-rays and theelectron microscope.In 1947 he persuaded theMedical Research Council(MRC) to support what he described as the "gallant attempt"[27]to determine protein structure as theLaboratory of Molecular Biology,initially consisting of Perutz,John Kendrewand two assistants. Bragg worked with them and by 1960 they had resolved the structure ofmyoglobinto the atomic level.[28]After this Bragg was less involved; their analysis ofhaemoglobinwas easier after they incorporated two mercury atoms as markers in each molecule. The first monumental triumph of the MRC was decoding the structure of DNA byJames WatsonandFrancis Crick.Bragg announced the discovery at aSolvay conferenceon proteins in Belgium on 8 April 1953, though it went unreported by the press. He then gave a talk atGuy's Hospital Medical Schoolin London on Thursday, 14 May 1953, which resulted in an article byRitchie Calderin theNews Chronicleof London on Friday, 15 May 1953, entitled "Why You Are You. Nearer Secret of Life". Bragg nominated Crick, Watson andMaurice Wilkinsfor the 1962 Nobel Prize in Physiology or Medicine; Wilkins' share recognised the contribution of X-ray crystallographers atKing's College London.[29]Among them wasRosalind Franklin,whose "photograph 51"showed that DNA was a doublehelix,not the triple helix thatLinus Paulinghad proposed. Franklin died before the prize (which only goes to living people) was awarded.

The Royal Institution (1954–1971)

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In 1953 the Braggs moved into the elegant flat for the Resident Professor in theRoyal Institutionin London, the position his father had occupied when he died. In 1934 and 1961 Lawrence had delivered theRoyal Institution Christmas Lectureand since 1938 he had been Professor of Natural Philosophy in the Institution, delivering an annual lecture. His father's successors had weakened the Institution, so Bragg had to rebuild it. He bolstered finances by enlisting corporate sponsors, the traditional Friday Evening Discourses were followed by a dinner party for the speaker and carefully selected possible patrons, more than 120 of them each year. "Two of these Discourses in 1965 gave him particular pleasure. On 7 May, Lady Bragg, who had been a member of the Royal Commission on Marriage and Divorce (1951–55) and was Chairman of theNational Marriage Guidance Council,lectured on 'Changing patterns in marriage and divorce'; and on 15 November, Bragg listened with evident pride to the Discourse on 'Oscillations and noise in jet engines' given by his engineer-sonStephen,who was then Chief Scientist at Rolls-Royce Ltd and later became Vice-Chancellor ofBrunel University."[30]He also introduced a programme of highly regarded Schools' Lectures, enlivened by the elaborate demonstrations that were a hallmark of the Institution. He gave three of these lectures on "electricity".[31]

He continued research in the Institution by recruiting a small group to work in the Davy-Faraday Laboratory in the basement and in the adjoining house, supported by grants he obtained. A visitor to the laboratory succeeded in inserting heavy metals into the enzymelysozyme;the structure of its crystal was solved in 1965 at the Royal Institution byD. C. Phillipsand his coworkers, with the computations on the 9,040 reflections performed on the digital computer at the University of London, which greatly facilitated the work.[32]Two of the illustrations of the positioning of amino acids in the chain were drawn by Bragg. Unlike myoglobin, in which nearly 80 per cent of the amino-acid residues are in thealpha-helixconformation, in lysozyme the alpha-helix content is only about 40 per cent of the amino-acid residues found in four main stretches. Other stretches are of the310helix,a conformation that they had proposed earlier.[33]In this conformation, every third peptide is hydrogen-bonded back to the first peptide, thus forming a ring containing ten atoms. They had the complete structure of an enzyme in time for Bragg's 75th birthday. He became Professor Emeritus in 1966.

X-ray analysis of protein structure flourished in subsequent years, determining the structures of scores of proteins in laboratories around the world. Twenty eight Nobel Prizes have been awarded for work using X-ray analysis. The disadvantage of the method is that it must be done on crystals, which precludes seeing changes in shape when enzymes bind substrates and the like. This problem was solved by the development of another line Bragg had initiated, using modified electron microscopes to image single frozen molecules:cryo-electron microscopy.[34]

In his long association with theRoyal Institutionhe was:

Personal life

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In 1921 he married Alice Hopkinson (1899–1989), a cousin of a friend who had been killed in the war. They had four children, the engineerStephen Lawrence(1923–2014), David William (1926–2005), Margaret Alice (1931–2022) (who married the diplomatMark Heath), and Patience Mary (1935–2020). Alice was on the staff atWithington Girls' Schooluntil Bragg was appointed director of the National Physical Laboratory in 1937.[24]She was active in a number of public bodies and served asMayor of Cambridgefrom 1945 to 1946.

Bragg's hobbies included drawing – family letters were illustrated with lively sketches – painting, literature and a lifelong interest in gardening.[35]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.[36]He died at a hospital near his home atWaldringfield,Ipswich,Suffolk. He was buried inTrinity College, Cambridge;his son David is buried in theParish of the Ascension Burial Groundin Cambridge, where Bragg's friend, who had he survived would have been his brother-in-law, Rudolph Cecil Hopkinson is also buried.

In August 2013, Bragg's relative, the broadcasterMelvyn Bragg,presented a BBC Radio 4 programme ( "Bragg on the Braggs" ) on the 1915 Nobel Prize in Physics winners.[37][38]

Honours and awards

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Bragg Family Blue Plaque Leeds

Bragg was elected aFellow of the Royal Society (FRS) in 1921[1]– "a qualification that makes other ones irrelevant".[39]He wasknightedbyKing George VIin the 1941 New Year Honours,[40]and received both theCopley Medaland theRoyal Medalof theRoyal Society.Although Graeme Hunter, in his book on BraggLight is a Messenger,argued that he was more a crystallographer than a physicist, Bragg's lifelong activity showed otherwise—he was more of a physicist than anything else. Thus, from 1939 to 1943, he served as President of theInstitute of Physics,London.[8]In the1967 New Year Honourshe was appointedMember of the Order of the Companions of HonourbyQueen Elizabeth II.[41]

Since 1967 theInstitute of Physicshas awarded theLawrence Bragg Medal and Prize.Additionally since 1992, theAustralian Institute of Physicshas awarded the Bragg Gold Medal for Excellence in Physics[42]to commemorate Lawrence Bragg (in front on the medal) and his father, William Bragg, for the best PhD thesis by a student at anAustralian university.

TheElectoral district of Bragg,in theSouth Australian House of Assembly,was created in 1970, and was named after both William and Lawrence Bragg.

See also

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References

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  1. ^abcPhillips, D.(1979). "William Lawrence Bragg. 31 March 1890 – 1 July 1971".Biographical Memoirs of Fellows of the Royal Society.25:74–143.doi:10.1098/rsbm.1979.0003.JSTOR769842.
  2. ^"Alexander Stokes".The Telegraph.28 February 2003.Retrieved16 January2016.
  3. ^"National Library of Wales: From Warfare to Welfare 1939–59".Archived fromthe originalon 18 November 2015.Retrieved17 November2015.
  4. ^abc"The Nobel Prize in Physics 1915".Nobel Foundation.Retrieved26 April2018.
  5. ^Stoddart, Charlotte (1 March 2022)."Structural biology: How proteins got their close-up".Knowable Magazine.doi:10.1146/knowable-022822-1.Retrieved25 March2022.
  6. ^"Facts on the Nobel Prize in Physics".Nobel Foundation.Retrieved16 January2016.
  7. ^Matthew, H. C. G.; Harrison, B., eds. (23 September 2004)."The Oxford Dictionary of National Biography".Oxford Dictionary of National Biography(online ed.). Oxford University Press. pp. ref:odnb/30845.doi:10.1093/ref:odnb/30845.Retrieved29 December2019.(Subscription orUK public library membershiprequired.)
  8. ^ab"Cambridge Physicists - William Lawrence Bragg".Cambridge Physics.Cavendish Laboratory.Retrieved26 April2018.
  9. ^SeeFred Hoyle's remarks regarding Hutchinson in 1965Galaxies, Nuclei and Quasarsp. 38 London: Heinemann; and R. J. N. Phillips 1987, "Some Words from a Former Student", inTribute to Paul Dirac,Bristol: Adam Hilger, p. 31.
  10. ^Jenkin, JohnWilliam and Lawrence Bragg; Father and Son.Oxford University Press 2008ISBN978 0 19 923520 9
  11. ^Laue, Max von."Concerning the Detection of X-ray Interferences".Nobel Prizes.Retrieved3 January2018.
  12. ^Van der Kloot, William (2014).Great Scientists wage the Great War.Stroud: Fonthill. p. 129.
  13. ^"No. 28879".The London Gazette.25 August 1914. p. 6702.
  14. ^William Van der Kloot,Lawrence Bragg's role in the development of sound-ranging in World War I,Notes and Records of the Royal Society,22 September 2005, vol. 59, no. 3, pp. 273–284.
  15. ^Van der Kloot 2014, pp. 129–161.
  16. ^"Casualty Details: Bragg, Robert Charles".Commonwealth War Graves Commission.Retrieved3 September2010.
  17. ^Cottrell, A.(1972)."Edward Neville da Costa Andrade. 1887-1971".Biographical Memoirs of Fellows of the Royal Society.18:1–20.doi:10.1098/rsbm.1972.0001.
  18. ^"No. 30450".The London Gazette(Supplement). 1 January 1918. p. 32.MC
  19. ^"No. 30576".The London Gazette(Supplement). 15 March 1918. p. 3289.OBE
  20. ^"No. 29623".The London Gazette(Supplement). 13 June 1916. p. 5930.mid
  21. ^"No. 29890".The London Gazette(Supplement). 2 January 1917. p. 207.mid
  22. ^"No. 31437".The London Gazette(Supplement). 4 July 1919. p. 8523.mid
  23. ^Van der Kloot 2014, pp. 207–208.
  24. ^abcNewsletter 1936-1937.Withington Girls' School. 1937.
  25. ^Bragg, W. Lawrence (1965)."Reginald William James. 1891–1964".Biographical Memoirs of Fellows of the Royal Society.11:114–125.doi:10.1098/rsbm.1965.0007.JSTOR769264.
  26. ^Phillips 1979, p. 117.
  27. ^Phillips 1979, p.118
  28. ^Bragg, Sir Lawrence; J. C. Kendrew; M. F. Perutz (1950). "Polypeptide chain configurations in crystalline proteins".Proc. R. Soc. Lond. A.203(1074): 321–357.Bibcode:1950RSPSA.203..321B.doi:10.1098/rspa.1950.0142.S2CID93804323.
  29. ^"Maurice Wilkins – Facts".Nobel Prize.Nobel Foundation.Retrieved26 April2018.
  30. ^Phillips 1979,p.126.
  31. ^"William Lawrence Bragg (1890-1971)".
  32. ^Blake, C. C. F.; D. F. Koenig; G. A. Mair; A. C. T. North; D. C. Phillips; V. R. Sarma (1965). "Structure of egg-white lysozome".Nature.206(4986): 757–761.Bibcode:1965Natur.206..757B.doi:10.1038/206757a0.PMID5891407.S2CID4161467.
  33. ^Bragg et al. 1950.
  34. ^"The Nobel Prize in Chemistry 2017".
  35. ^Thomson, Patience (2013)."A tribute to W. L. Bragg by his younger daughter"(PDF).Acta Crystallographica Section A.A69(Pt 1): 5–7.Bibcode:2013AcCrA..69....5T.doi:10.1107/S0108767312047514.PMID23250053.Retrieved24 December2012.
  36. ^Crick, Francis (1989).What Mad Pursuit.Weidenfeld & Nicolson. p. 53.ISBN978-0140119732.
  37. ^"Bragg on the Braggs".2 March 2017.
  38. ^"BBC Radio 4 - Bragg on the Braggs".
  39. ^G. K. Hunter 2004Light is a MessengerOxford: OUP.
  40. ^"No. 35029".The London Gazette(Supplement). 31 December 1940. p. 1.Knight bachelor
  41. ^"No. 44210".The London Gazette(Supplement). 30 December 1966. p. 26.CH
  42. ^Bragg Gold Medal for Excellence in PhysicsArchived14 July 2014 at theWayback Machine

Further reading

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  • Hunter, Graeme (2004).Light Is A Messenger, the Life and Science of William Lawrence Bragg.Oxford: Oxford University Press.ISBN0-19-852921-X.
  • Finch, John (2008).A Nobel Fellow On Every Floor.Medical Research Council.ISBN978-1-84046-940-0.(This book is about the MRC Laboratory of Molecular Biology, Cambridge.)
  • Ridley, Matt(2006).Francis Crick: Discoverer of the Genetic Code.Eminent Lives. HarperCollins.ISBN0-06-082333-X.
  • Jenkin, John (2008).William and Lawrence Bragg, Father and Son: The Most Extraordinary Collaboration in Science.Oxford: Oxford University Press.
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Academic offices
Preceded by Langworthy Professorat theUniversity of Manchester
1919–37 		Succeeded by
Preceded by Cavendish Professor of Experimental Physics,University of Cambridge
1938-1953 		Succeeded by
Professional and academic associations
Preceded by
Herbert Levinstein
 President of theManchester Literary and Philosophical Society
1927–29 		Succeeded by
Charles Edmond Stromeyer
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