We see a shy, introverted girl — handsome but not beautiful — blossom into an aggressive researcher. Physics was her life; Sime found no evidence that Meitner was ever involved in a romantic relationship. The Washington post
I will have nothing to do with a bomb. Lise Meitner
While professional jealousies only threatened to keep Marie Curie from receiving the Nobel Prize, they succeeded in denying Meitner the same recognition. With her name missing from the key experimental paper on nuclear fission (previously Meitner and Hahn always shared the credit on their joint efforts), Hahn alone received the 1944 prize for chemistry. Sime shines an insightful spotlight on the politics of science through this biography — how the idealistic quest for scientific knowledge can be sullied by a scientist’s obsessive watch over citations and credit. It is thus surprising to discover that Meitner remained loyal to Hahn throughout this turmoil. In fact, horrified by the bomb, fission’s offspring, she had mixed feelings about being linked in any way to its creation. WP
With the discovery of the neutron in the early 1930s, the scientific community began to speculate that it might be possible to create elements heavier than uranium in the lab. A race to confirm this began between Ernest Rutherford in Britain, Irene Joliot-Curie in France, Enrico Fermi in Italy and the Meitner-Hahn team in Berlin. The teams knew the winner would likely be honored with a Nobel Prize. Wired
Attention: un prix Nobel peut en cacher un autre !
Marcia Bartusiak
The Washington Post
March 17, 1996
In the history of modern physics there are names that perpetually resonate: Ernest Rutherford and Niels Bohr for unveiling the secrets of atomic structure, Erwin Schroedinger and Werner Heisenberg for establishing the rules of the quantum game, and Albert Einstein for recognizing that mass is frozen energy. In this company the name Lise Meitner has diminished to a footnote.
Yet in her day she had a reputation as one of Germany’s best experimentalists. Einstein fondly referred to her as « our Marie Curie. » Meitner’s perceptive realization that atomic nuclei can be split in half was the first step in a cascading set of discoveries that would relentlessly lead to the atomic bomb. But, in the midst of these revelations, Meitner had to flee from Nazi Germany, which cut her off from her laboratory and colleagues. While this exile saved her life, it cost her the Nobel Prize and a prominent niche in many annals of physics.
Fortunately, attention is gradually being refocused on this remarkable woman. Richard Rhodes devoted an appreciable section in The Making of the Atomic Bomb to Meitner’s work on nuclear fission. And now Ruth Lewin Sime, a chemist at Sacramento City College, has written the definitive scientific biography of Meitner, a riveting and masterful account of a scientist’s steadfast devotion to physics. Sims blends the science and history with seamless ease. Even though decades have passed since the collapse of the Third Reich, Sime’s extensive research offers fresh insights on the devastating legacy of Nazism’s distortion of the scientific truth.
Born in Vienna in 1878, Meitner was one of eight children; her father was among the first group of Jewish men to practice law in Austria. As with Curie (but rare for a woman at the turn of the century), the intellectual atmosphere that surrounded Meitner as a child nurtured her scientific proclivity. Only the second woman to obtain a doctoral degree in physics at the University of Vienna, she was soon drawn into the novel study of radioactivity.
In 1907 she moved to Berlin, the mecca of theoretical physics, where she was introduced to Einstein and Max Planck, the father of the quantum. More important, she met Otto Hahn, who became her closest collaborator and a valued friend. They were an interdisciplinary yin and yang: Hahn, the chemist, Meitner,the physicist. While he was methodical, she was bold. Together, in 1917, they discovered a new element, protactinium.
Despite the terrible gender discriminations of the time (especially in Germany), Meitner’s deft abilities could not be ignored. By 1917, still in her thirties, she was given her own physics section in the prestigious Kaiser Wilhelm Institute for Chemistry. In 1934 she convinced Hahn to join with her once again to investigate the very heart of the atom, its nucleus, and seek elements beyond uranium, then the heaviest atom known.
By bombarding uranium with neutron particles, the two researchers encountered a nightmarish jumble of radioactive species that could not be easily identified. For four long years, Hahn, the expert chemist, carefully separated and processed the radioactive materials; Meitner’s job was to explain the nuclear processes going on. Sime, so obviously at home with the periodic table of the chemical elements, dissects each and every one of Hahn and Meitner’s experiments to a degree that only a specialist can follow. Newcomers to this material would have been helped by some simple diagrams of atomic structure and an introductory overview of nuclear physics. Yet it is through such detail that the reader comes to appreciate Meitner’s originality of thought and creativity at the laboratory bench. We see a shy, introverted girl — handsome but not beautiful — blossom into an aggressive researcher. Physics was her life; Sime found no evidence that Meitner was ever involved in a romantic relationship.
Throughout these years Hitler was casting his long, dark shadow upon Europe. Sime’s engrossing narrative shows how easy it was for so-called « good » Germans to rationalize their compromises and look the other way. Dismissed from teaching, her name suppressed, Meitner hung on without protest, nervously hoping that the unpleasantness would be temporary. Although of Jewish descent, she had been baptized a Protestant and loved her country.
But as restrictions on « non-Aryan » academics tightened, Meitner at last slipped across the border with only a small valise carrying a few summer clothes. She was 59. Her mind as vigorous as ever, she continued to advise Hahn through letters from Sweden, which became her new home.
A breakthrough in their work came at the end of 1938, just months after Meitner fled Germany. At Meitner’s direction from afar, Hahn and his assistant Fritz Strassmann more closely analyzed the byproducts of the neutron-bombardment experiments. To their amazement, the elements weren’t heavier than uranium, but lighter. « Perhaps you can come up with some sort of fantastic explanation, » Hahn wrote Meitner. « We knew ourselves that [uranium] can’t actually burst apart into [barium]. »Within days, collaborating with her nephew Otto Robert Frisch, also a noted physicist, she worked out a theoretical model of nuclear fission.
Hahn published the chemical evidence for fission without listing Meitner as a co-author, a move she understood given the tinderbox that was Nazi Germany. In The Making of the Atomic Bomb Rhodes wrote that Hahn had always hoped to add Meitner’s name to this historic paper; Sime tells a different story. She builds a strong case that Hahn was distancing himself from his longtime collaborator even before Meitner escaped. More tragic was Hahn’s conduct after the war; he maintained the fiction (or convinced himself) that his chemical experiments verifying fission had never been inspired or guided by Meitner. And, over the years, this version of the tale lived on. Meitner, Hahn’s equal partner at the Institute for 30 years, came to be mistakenly known as his junior assistant.
While professional jealousies only threatened to keep Marie Currie from receiving the Nobel Prize, they succeeded in denying Meitner the same recognition. With her name missing from the key experimental paper on nuclear fission (previously Meitner and Hahn always shared the credit on their joint efforts), Hahn alone received the 1944 prize for chemistry. Sime shines an insightful spotlight on the politics of science through this biography — how the idealistic quest for scientific knowledge can be sullied by a scientist’s obsessive watch over citations and credit. It is thus surprising to discover that Meitner remained loyal to Hahn throughout this turmoil. In fact, horrified by the bomb, fission’s offspring, she had mixed feelings about being linked in any way to its creation.
But there is a happy ending yet. Though denied the coveted Nobel, Meitner will be rewarded with far more durable fame: a permanent abode on the periodic table. In 1994 an international commission agreed that element 109, artificially created in Germany by slamming bismuth with iron ions, will be named « meitnerium. »
Marcia Bartusiak regularly writes on astronomy and physics. The author of « Thursday’s Universe » and « Through a Universe Darkly, » she is an adjunct professor of science journalism at Boston University.
Voir aussi:
Feb, 11, 1939: Lise Meitner, ‘Our Madame Curie’
Beverly Hanly
Wired
February 11, 2010
1939: Austrian-born physicist Lise Meitner publishes her discovery that atomic nuclei split during some uranium reactions. Her research will be overlooked by the Nobel committee when it awards a prize for the work.
Meitner is a prominent example of a woman whose gender put her in the back seat when the top prize was given. The political climate in Nazi Germany contributed to her obscurity — as a Jew, she had to flee the country to survive, but leaving cost her the chance to publish with her colleagues. Plain old scientific jealousy also played a part in who got credit for discoveries that led to splitting the atom and, ultimately, the atomic bomb and nuclear power.
Other honors would come late in life to Meitner. Einstein even called her “our Marie Curie.”
Meitner was born in Austria in 1878 to Jewish parents. Women were not allowed to attend institutions of higher learning in those days, so she had to study privately to earn a doctoral degree in physics in 1905 at the University of Vienna. Meitner was only the second woman to do so.
She went to Berlin, where she met Einstein and attended lectures by Max Planck. Planck had previously refused to teach women, but after a year, she became his assistant and teamed up with chemist Otto Hahn. They discovered several new isotopes, and in 1909 she presented two papers on beta radiation.
When Meitner and Hahn moved to the new Kaiser Wilhelm Institute in Berlin in 1912, she worked unpaid in Hahn’s department of Radiochemistry. She got a paid position at the institute in 1913, only after being offered an assistant professorship in Prague. She was given her own physics section at the prestigious academy in 1917.
She and Hahn were a productive team. They discovered the first long-lived isotope of the element protactinium. Meitner isolated the cause of the emission from atomic surfaces of electrons with “signature” energies in 1923, but the French scientist Pierre Auger made the same discovery independently in 1925 and his name was attached to the phenomenon. It’s been known thereafter as the “Auger effect.”
With the discovery of the neutron in the early 1930s, the scientific community began to speculate that it might be possible to create elements heavier than uranium in the lab. A race to confirm this began between Ernest Rutherford in Britain, Irene Joliot-Curie in France, Enrico Fermi in Italy and the Meitner-Hahn team in Berlin. The teams knew the winner would likely be honored with a Nobel Prize.
When Adolf Hitler came to power in 1933, Meitner was acting director of the Institute for Chemistry. Her Austrian citizenship protected her, but other Jewish scientists — including her nephew Otto Frisch, Fritz Haber, Leó Szilárd and many others — lost their posts and most left Germany.
Meitner buried herself in her work, but when Austria was annexed by the Nazi regime, she had to flee. Dutch physicists helped her escape to Holland in July 1938. She was 59 when she landed in Sweden, where she worked with Niels Bohr and corresponded with Hahn and other German scientists. Later that year, she met Hahn secretly in Copenhagen to plan a new series of experiments.
Now, it gets tricky. Hahn performed the experiments that isolated the evidence for nuclear fission, finding that neutron bombardment produced elements that were lighter than uranium. But he was mystified by those results.
“Perhaps you can come up with some sort of fantastic explanation,” Hahn wrote Meitner. “We knew ourselves that [uranium] can’t actually burst apart into [barium].”
Meitner and Frisch quickly came up with a theory that explained nuclear fission, resolving Hahn’s key problem. “Hahn published the chemical evidence for fission without listing Meitner as a co-author,” writes The Washington Post in a review of a Meitner biography. “[It was] a move she understood, given the tinderbox that was Nazi Germany.”
A letter from Bohr documents her inspiration in December 1938. Although some historians say that Hahn hoped he would be able to add her name later, others report that he maintained the fiction that Meitner functioned as a junior assistant. Whatever his intention, her insights were key to his discoveries — and to the developments in radioactivity and nuclear processes that changed the world.
Meitner and Frisch made other key discoveries. They explained why no stable elements beyond uranium existed naturally. And she was the first to see that Einstein’s E = mc2 explained the source of the tremendous releases of energy in atomic decay, by the conversion of the mass into energy.
The aunt and nephew coined the term “nuclear fission” when they published “Disintegration of Uranium by Neutrons: A New Type of Nuclear Reaction” in the journal Nature on Feb. 11, 1939. Instrumental as they were in the discovery (.pdf), they were still overlooked when it came to awarding the 1944 Nobel Prize in Chemistry. It was Hahn alone who received the prize.
Meitner’s realization that nuclear fission made possible a chain reaction of huge explosive power had meanwhile galvanized members of the scientific community to act. Knowing German scientists had the knowledge, Leo Szilard, Edward Teller and Eugene Wigner convinced Albert Einstein to use his celebrity and warn President Franklin D. Roosevelt. The result was the Manhattan Project.
Meitner was invited to work on the Manhattan project at Los Alamos, but categorically declined: “I will have nothing to do with a bomb.”
Refusing to move back to Germany, even when it was safe for her to do so, she worked in Stockholm doing research into her late 80s. She conducted atomic research, including work on R1, Sweden’s first nuclear reactor.
Meitner received many awards later in her lifetime. Element 109, meitnerium, is named in her honor, and her picture appeared on an Austrian stamp. She received many honorary doctorates and lectured at Princeton, Harvard and other U.S. universities. In 1946, she was named “Woman of the Year” by the National Press Club at a dinner with President Harry Truman.
The German Physics Society gave her the Max Planck Medal in 1949. Hahn, Meitner and Fritz Strassmann won the Enrico Fermi Award in 1966.
Meitner died in 1968, a few weeks shy of her 90th birthday. She had mixed feelings about being associated with work that led to the A-bomb, so perhaps the fact that her role in discovering nuclear fission was not widely known is a kind of blessing.
Voir également:
Il y a 75 ans, le Nobel de physique récompensait… une incroyable erreur
Passeur de sciences
Pierre Barthélémy
6 octobre 2013
Lundi 7 octobre s’ouvre la grande parade annuelle des prix Nobel, avec la catégorie « physiologie ou médecine ». Suivront la physique (le 8 octobre), la chimie (le 9), la paix (le 11), les sciences économiques (le 14) et la littérature à une date qui n’est pas encore déterminée. 2013 est l’occasion d’un curieux anniversaire puisqu’on fête cette année les 75 ans de ce qu’on peut appeler le prix Nobel de l’erreur et ce dans le domaine qui est censé être le plus précis de tous ceux que cette récompense recouvre, à savoir la physique.
En 1938, c’est l’immense chercheur italien Enrico Fermi qui reçoit la distinction suprême pour, je cite, « sa découverte de nouveaux éléments radioactifs, développés par l’irradiation des neutrons, et sa découverte à ce propos des réactions de noyaux, effectuées au moyen des neutrons lents ». Le communiqué explicite cette découverte ainsi : “Fermi a en effet réussi à produire deux nouveaux éléments, dont les numéros d’ordre sont 93 et 94, éléments auxquels il a donné le nom d’ausénium et d’hespérium.” Seulement voilà, d’ausénium et d’hespérium il n’y avait en réalité point dans l’expérience du savant transalpin. Fermi s’était trompé dans son interprétation et il avait néanmoins eu le prix Nobel pour la découverte de deux éléments imaginaires…
Pour comprendre cette erreur, il faut replonger dans les années 1930, ère des pionniers du noyau atomique. L’histoire illustre à merveille la manière dont la science se trompe, se corrige et, ce faisant, s’améliore. Que fait Enrico Fermi dans l’expérience qui lui vaut ce Nobel, relatée en 1934 dans Nature ? A l’époque, on ne connaît pas d’élément chimique dont le noyau contienne davantage de protons que l’uranium (92) et le chercheur italien se demande s’il est possible de synthétiser des éléments plus lourds. Son idée est de profiter de la radioactivité bêta qu’il vient de modéliser et grâce à laquelle un neutron peut se transformer en proton (ou le contraire). Pour son expérience, Fermi part de l’idée qu’en bombardant de neutrons des noyaux d’uranium, ceux-ci vont finir par absorber un neutron qui, sous l’effet la radioactivité bêta, se transformera en proton. Le noyau aura finalement gagné un proton, ce qui aura « transmuté » l’uranium à 92 protons en élément nouveau à 93 protons (que Fermi appellera ausénium). Après une nouvelle étape, celui-ci se métamorphosera en élément à 94 protons (nommé hespérium). La difficulté de l’expérience consiste à détecter la présence de ces nouveaux éléments. Fermi ne les identifie pas chimiquement : il se contente de constater que l’expérience produit deux « choses » radioactives dont les caractéristiques sont inconnues. Pour lui, c’est la preuve, certes indirecte, mais la preuve quand même, qu’il a synthétisé deux nouveaux éléments.
Comme l’explique Martin Quack, chercheur à l’Ecole polytechnique fédérale de Zurich, dans l’article qu’il a récemment consacré à cette histoire (publié par Angewandte Chemie International Edition), Enrico Fermi est au départ plutôt prudent dans sa formulation. Mais les années passant et rien ne venant contredire cette interprétation, cette prudence s’estompe et l’on considère le résultat comme acquis, d’autant que la stature scientifique de l’Italien est immense. La chimiste allemande Ida Noddack tente bien d’avancer que le niveau de preuve n’est pas suffisant, mais personne ne tient vraiment compte de ses objections. Un magnifique cas d’école de l’aveuglement des experts.
Tout se précipite à la fin 1938, comme dans un thriller scientifique où le temps se condense et s’accélère. Le 12 décembre, Enrico Fermi reçoit à Stockholm son prix Nobel des mains du roi de Suède. Il en profite pour fuir aux Etats-Unis, la situation de son épouse, qui est juive, étant de plus en plus précaire dans l’Italie mussolinienne. Une semaine plus tard, le 19, le chimiste allemand Otto Hahn, qui a, avec Fritz Strassmann, reproduit l’expérience de Fermi, envoie ses résultats à sa consœur Lise Meitner : les produits de l’expérience ne sont pas des éléments superlourds. Au contraire, cela ressemble à des isotopes inconnus d’éléments plus légers, notamment du baryum (56 protons). Mais comment diable de l’uranium peut-il donner du baryum ? Pendant les vacances de Noël, Lise Meitner discute avec son neveu, Otto Frisch de la possibilité théorique qu’un noyau d’uranium se brise pour donner des noyaux plus légers. Ils écrivent un article en ce sens qui sera publié en février 1939. Ce qu’avait réalisé Enrico Fermi sans le comprendre, c’était la première expérience de fission nucléaire !
Le coupable était dans l’uranium. Le minerai naturel d’uranium contient deux isotopes de cet élément. Le premier, l’uranium 238 (92 protons + 146 neutrons) est de très loin le plus courant puisqu’il représente plus de 99 % du minerai. Le second, l’uranium 235 (92 protons + 143 neutrons) est beaucoup plus rare (0,7 %) au point qu’on peut le considérer comme une impureté. C’est lui qui est fissile et que l’on emploie dans de nombreux réacteurs nucléaires. Et c’est aussi lui qui se trouvait dans la bombe atomique d’Hiroshima. Dans l’expérience de Fermi, le bombardement de neutrons n’a, contrairement à ce qu’espérait le savant italien, rien fait aux atomes d’uranium 238. En revanche, il a provoqué la fission des noyaux d’uranium 235. Les produits nouveaux qu’a détectés l’Italien étaient des produits de fission, des éléments plus légers, inconnus sous cette forme radioactive, comme le baryum 140.
Enrico Fermi méritait sans doute un Nobel et il est dommage qu’il l’ait reçu pour une expérience mal interprétée et pas assez approfondie. Dès qu’il apprit la découverte de Hahn et Strassmann, début 1939, il modifia son discours de réception du prix pour intégrer ce nouveau résultat, preuve d’une grande honnêteté intellectuelle. Les deux chercheurs allemands reçurent le Nobel de chimie 1944 pour la fission nucléaire (Lise Meitner étant scandaleusement oubliée dans l’histoire) et, d’une certaine manière, pour avoir corrigé l’erreur de Fermi. Ce dernier réalisa, en collaboration avec Leo Szilard, la première pile atomique en 1942, c’est-à-dire la première réaction nucléaire en chaîne contrôlée de l’histoire. Et, bien sûr, Fermi travailla pour le projet Manhattan qui mena à la bombe atomique. Quant aux éléments 93 et 94, le neptunium et le plutonium, ils furent bel et bien produits selon le processus qu’avait prévu Fermi. En 1951, on donna donc de nouveau un prix Nobel (de chimie) à ceux qui les avaient mis en évidence, mais cette fois-ci pour de vrai : Glenn Seaborg et Edwin McMillan.
Trois-quarts de siècle après le Nobel de l’erreur, l’histoire vient rappeler que la science a deux versants inséparables, le côté créatif et le côté critique. Comme le souligne Martin Quack dans son article, « la composante créative s’engage dans de nouvelles idées et dans des avenues inexplorées (…). Elle se vend bien grâce au terme chic de « nouveau ». Cependant, la composante critique est tout aussi importante que la composante créative. Elle interroge le résultat « nouveau », soumettant ses faiblesses à une critique sévère, répétant et testant les résultats dans de longues enquêtes impliquant un dur labeur. Souvent elle rejette ou corrige le résultat original et mène parfois à une découverte encore plus frappante. » Vérifier les résultats des autres a des airs austères et tristes de police scientifique mais conduit parfois à la révolution.
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