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11 de Maig   2017
Ressenya Dr. XAVIER ROQUÉ

Ressenya amb anglès

Meitner, Lise (1878-1968), physicist

by Xavier Roqué

© Oxford University Press 2004 All rights reserved
Meitner, Lise (1878-1968), physicist, was born on 7 November 1878 at 27 Kaiser Josefstrasse, Vienna, thethird of the eight children of Philipp Meitner (d. 1910), a lawyer, and his wife, Hedwig Skovran (1850–1924). Both parents were of Jewish descent, yet Meitner accepted baptism as a protestant in 1908. As awoman scientist, Lise Meitner had to struggle to launch a career. She trained as a French teacher yet,crucially, her family backed her decision to pursue a higher education when in 1897 women were granted access to the philosophical faculties of Austrian universities. After training privately to take the required examination she entered the University of Vienna in 1901. She studied physics and mathematics with the renowned Ludwig Boltzmann, and in 1906 took her PhD under Franz Exner, on heat conduction in inhomogeneous solids. She then turned to the new field of radioactivity, to which she was to devote her scientific work.
The study of radioactivity thrived in Vienna yet chances to get a position were slim. In 1907, with herfamily’s continued financial support, Meitner moved to Berlin. She attended Max Planck’s lectures at theuniversity and met an assistant at Emil Fischer’s chemistry institute, Otto Hahn, an early advocate of radioactivity in Germany. In the years leading to the First World War Meitner collaborated with Hahn on the identification and separation of new radioactive substances, and entered the German academic system: in 1912, at thirty-five, she obtained her first paid position, as Planck’s assistant, and that same year shemoved with Hahn to the radioactive section of the new Kaiser Wilhelm Institut für Chemie, one in a series of research centres funded by German industrialists. In 1913 she became an associate at the institute, and in 1917, after a year serving as an X-ray nurse–technician with the Austrian army, she was appointed director of its physics section. During the war she managed to complete, with Hahn’s occasional assistance when on leave, the search for the precursor of actinium—protactinium (Pa, element 91). Meitner secured the necessary pitchblende residues from the chemical firm Buchler’s industrial laboratory in Brunswick, where part of the treatment was also carried out. Meitner built her prestige as a physicist during the Weimar years (1918–33)—her best both professionally and personally. In 1922 she received the venia legendi , which qualified her for teaching at the university,and in 1926 she was appointed extraordinary professor. The human and material resources of her laboratory at the Kaiser Wilhelm Institut grew steadily after temporary setbacks during the 1922–3 inflation, making it, together with Hahn’s chemical section, Germany’s most important radioactive research centre.
During this period Meitner studied the relationship between beta and gamma rays, with important implications for nuclear structure. In the context of a long-standing controversy with C. D. Ellis, from the Cavendish Laboratory in Cambridge, she established in 1925 that gamma-ray emission followed, rather than triggered, radioactive transformations, though she later confirmed Ellis and W. A. Wooster’s result that the primary beta-spectrum was continuous. Beginning in 1929, a substantial mesothorium (228Ra) and radiothorium (228Th) loan from the Kaiser Wilhelm Gesellschaft allowed her and her co-workers to study the absorption of high-energy gamma rays in matter—a topic of relevance for the physics of the nucleus and cosmic rays. In these experiments Meitner used the newly developed Geiger-Müller counter; as with the cloud chamber before, she was quick in adapting new instruments. By virtue of its technical expertise and its stock of radioactive sources Meitner’s section also played a substantial role in the study of the new particles of the early 1930s, the neutron and the positron.
As an Austrian citizen and non-state employee, Meitner was spared the Nazis’ first racial laws (introduced
Oxford DNB article: Meitner, Lise 18/06/10 17:15
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in 1933). She considered leaving Germany at the time, yet the excellent work conditions at the institute prevailed. The removal of her venia legendi and increasing isolation may have conditioned her resuming collaborative work with Hahn. For four years, with a younger researcher, Fritz Strassmann, they studied the radioactive elements formed in the bombardment of uranium nuclei by neutrons, some of which were presumed to be heavier than uranium itself (to have an atomic number over 92).In July 1938, three months after the annexation of Austria by the Reich, Meitner fled Germany. From herexile in Sweden she learned firsthand of Hahn and Strassmann’s result that barium (an element about half the atomic weight of uranium) was among the products of the collision of a neutron with an uranium nucleus. This seemed very implausible physically. Her nephew, the physicist Otto Robert Frisch, was visiting; over Christmas they arrived at an explanation in terms of the excessive electric charge of the nucleus, and estimated the energy released in the process, for which Frisch proposed the term ‘fission’.m Meitner spent twenty years in Sweden, becoming a Swedish citizen in 1949. During the war she tried to pursue fission research at Magne Siegbahn’s research institute in Stockholm. Her situation improved in 1947, when together with Sigvard Ecklund she was assigned the creation of a nuclear physics section at the Swedish Royal Institute of Technology. She retired in 1954, was elected a fellow of the Royal Society of London the following year, and in 1960 moved to Cambridge, where Frisch lived. She died at Cambridge on 27 October 1968 and was buried at Bramley in Hampshire. Meitner’s share in the discovery of fission continues to dominate judgements of her stature as a scientist. In 1945 Hahn alone was controversially awarded the 1944 chemistry Nobel prize for this discovery. Recent work has made clear that Meitner contributed decisively to the discovery, that the Nobel committee’s decision was characteristically open to question, and that Hahn did not do much to clarify Meitner’s role.The historiographical dominance of this issue has unfortunately prevented many from arriving at abalanced view of Meitner’s achievements as a physicist, particularly with regard to her prominent role in the development of radioactivity and the rise of nuclear physics in Germany.

XAVIER ROQUÉ

Sources

  1. L. Sime, Lise Meitner: a life in physics (1996) · O. R. Frisch, Memoirs FRS, 16 (1970), 405–20 · E. Crawford, R. L. Sime, and M. Walker, ‘A Nobel tale of wartime injustice’, Nature, 382 (1996), 393–5 · S. Ernst, ed., Lise Meitner an Otto Hahn: Briefe aus den Jahren 1912 bis 1914 (1992) · CGPLA Eng. & Wales (1969) · E. Scheich, ‘Science, politics, and morality: the relationship of Lise Meitner and Elizabeth Schiemann’, Osiris, 2nd ser., 12 (1997), 143–68

Archives

CAC Cam., personal and scientific papers | Archiv zur Geschichte der Max-Planck-Gesellschaft, Berlin, O. Hahn Nachlass · Archiv zur Geschichte der Max-Planck-Gesellschaft, Berlin, Kaiser-Wilhelm-Institut für Chemie · Royal Swedish Academy of Sciences, Stockholm, Nobel archives · Trinity Cam., O. R. Frisch collection · University of Chicago, Joseph Regenstein Library, James Franck MSS

FILM

BBC Archive, London · CAC Cam., Meitner Collection

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Ressenya en Català

La història de Lise Meitner és, des del principi, una aventura de superació. Va estudiar física i es va convertir en la segona dona a graduar-se en la Universitat de Viena el 1905, quan no era gens comú que les dones accedissin a cicles superiors. Tot i que pocs professors acceptaven la seva presència, va viatjar a Berlín i allà va seguir atenent a classes fins que un professor la va acollir com el seu assistent.

En aquesta època, va conèixer al químic Otto Hahn, amb qui formaria una parella professional que anava a allargar-se en el temps. Però era un equip desigual. Aquells eren temps especialment durs per a les dones i, fins que no va complir 35 anys, no va començar a treballar sota una remuneració econòmica. No era el primer escull que es trobava, però tampoc anava a ser l’últim.

Les grans guerres

La primera Guerra Mundial va esclatar i allà estava Meitner, que va servir com a infermera al front. Quan va tornar als seus estudis, en certa manera se sentia avergonyida de reprendre les seves investigacions en una època en què les víctimes de la guerra seguien patint. Aquesta marca del seu caràcter no l’abandonaria mai.

En anys successius, els seus descobriments (energia nuclear) en el camp de la química van començar a ser reconeguts i, el 1926, es va convertir en la primera professora de Física a Alemanya, a la Universitat de Berlín. Albert Einstein es va referir a ella com la Marie Curie alemanya.

Quan Adolf Hitler va ascendir al poder, Meitner va abandonar Alemanya. Com tants altres, ho va fer oculta, amb l’ajuda de dos companys holandesos amb els que va creuar la frontera. Va reprendre la seva activitat científica a Estocolm, després d’abandonar els Països Baixos. Ja des de Dinamarca, va seguir en contacte amb el seu company Hahn i amb altres investigadors alemanys, amb qui va mantenir la col·laboració.

Durant els anys trenta, els avanços en física i química conduirien fins a la terrorífica construcció de les devastadores armes nuclears. Però en aquelles primeres investigacions no es tenia ni tan sols sospita d’això.

Meitner i el seu nebot, també investigador, van ser els primers a desenvolupar una teoria sobre com els nuclis d’un àtom podien trencar-se en parts més petites, una idea que feia temps que rondant però que no havia estat confirmada. També va ser ella la primera a adonar-se que la famosa equació d’Einstein, E = mc2, explicava per què en la fissió nuclear s’alliberava tanta quantitat d’energia … i també que tota aquesta energia podia ser utilitzada per construir armes.

Quan aquesta possibilitat es va fer coneguda en el món científic, i sabent que els alemanys tenien la informació en el seu poder, algunes personalitats d’aquest àmbit van intentar fer veure als governants el perillós d’aplicar els seus descobriments a la indústria armamentista. A Meitner van arribar a oferir-li treballar en el projecte americà, però ella ho va rebutjar. Sempre es va oposar a aquest ús de l’energia nuclear.

El Nobel que mai va arribar

Va passar al novembre de 1945. La Reial Acadèmia de les Ciències de Suècia va anunciar que Otto Hahn, el col·lega de Lise Meitner, havia de ser guardonat amb el Premi Nobel de Química pels seus descobriments en fissió nuclear.Meitner havia estat una peça fonamental en totes les investigacions i, en canvi, no es va prestar atenció a la seva figura. Sovint, se cita aquesta científica com un dels casos més clars en els quals els màxims reconeixements han passat de llarg.

En anys posteriors, altres premis si la van tenir en compte. Fins i tot en 1997 es va cridar a un element de la taula periòdica, el nombre 109, en el seu honor: meitneri . Però cap de la magnitud del Nobel.

Durant els seus últims anys, va seguir involucrada en el món de la ciència, com a investigadora i també com a professora. Lise Meitner va ser una de les científiques més importants del segle XX. Tot i les dificultats que va viure al llarg de la seva vida, al règim nazi o al poc reconeixement del seu treball, va estar sempre entregada a la investigació i al progrés.

Carme Mas – ASCV

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