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Friday, May 18, 2012

Famous Scientist ( Lise Meitner )

-: Lise Meitner :-

Lise Meitner

Lise Meitner, FRS (7 November 1878 – 27 October 1968) was an Austrian, later Swedish, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize.  Meitner is often mentioned as one of the most glaring examples of women's scientific achievement overlooked by the Nobel committee. A 1997 Physics Today study concluded that Meitner's omission was "a rare instance in which personal negative opinions apparently led to the exclusion of a deserving scientist" from the Nobel. Element 109, Meitnerium, is named in her honour.

Meitner was born into a Jewish family as the third of eight children in Vienna, 2nd district (Leopoldstadt). Her father, Philipp Meitner, was one of the first Jewish lawyers in Austria. She was born on 7 November 1878. She shortened her name from Elise to Lise. The birth register of Vienna's Jewish community lists Meitner as being born on 17 November 1878, but all other documents list it as 7 November, which is what she used. As an adult, she converted to Christianity, following Lutheranism, and being baptized in 1908.

Inspired by her teacher, physicist Ludwig Boltzmann, Meitner studied physics and became the second woman to obtain a doctoral degree in physics at the University of Vienna in 1905 ("Wärmeleitung im inhomogenen Körper"). Women were not allowed to attend institutions of higher education in those days, but thanks to support from her parents, she was able to obtain private higher education, which she completed in 1901 with an "externe Matura" examination at the Akademisches Gymnasium. Following the doctoral degree, she rejected an offer to work in a gas lamp factory. Encouraged by her father and backed by his financial support, she went to Berlin. Max Planck allowed her to attend his lectures, an unusual gesture by Planck, who until then had rejected any women wanting to attend his lectures. After one year, Meitner became Planck's assistant. During the first years she worked together with chemist Otto Hahn and discovered with him several new isotopes. In 1909 she presented two papers on beta-radiation.

Hahn and Meitner met privately in Copenhagen in November to plan a new round of experiments, and they subsequently exchanged a series of letters. Hahn and Fritz Strassmann then performed the difficult experiments which isolated the evidence for nuclear fission at his laboratory in Berlin. The surviving correspondence shows that Hahn recognized that fission was the only explanation for the barium, but, baffled by this remarkable conclusion, he wrote to Meitner. The possibility that uranium nuclei might break up under neutron bombardment had been suggested years before, notably by Ida Noddack in 1934. However, by employing the existing "liquid-drop" model of the nucleus, Meitner and Frisch were the first to articulate a theory of how the nucleus of an atom could be split into smaller parts: uranium nuclei had split to form barium and krypton, accompanied by the ejection of several neutrons and a large amount of energy (the latter two products accounting for the loss in mass). She and Frisch had discovered the reason that no stable elements beyond uranium (in atomic number) existed naturally; the electrical repulsion of so many protons overcame the strong nuclear force. Meitner also first realized that Einstein's famous equation, E = mc2, explained the source of the tremendous releases of energy in nuclear fission, by the conversion of rest mass into kinetic energy, popularly described as the conversion of mass into energy.

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