Marie Curie and Lise Meitner
As the IOP hosts a talk on pioneering women in physics, we profile two of those featured: Marie Curie and Lise Meitner.
Marie Curie was born Maria Skłodowska in 1867 in Warsaw, Poland, then part of the Russian Empire. Amid a climate that made it difficult for Poles, and especially, women, to take part in higher education, she studied in the city’s “Floating University” – a covert educational network that held classes in private houses.
In 1891 she left for France to study at the University of Paris, gaining a degree in physics two years later and another in maths a year after that. She married fellow scientist Pierre Curie in 1895 and the following year began research into the strange radiation newly discovered to be emitted by uranium.
The Curies’ first daughter, Irène, was born in 1897, and in 1898 Pierre gave up his own research to join his wife’s efforts in understanding what they would come to call “radioactivity”. That year, the pair discovered two new elements – radium and polonium, the later named after Marie’s native country. The Curies were recognised with the 1903 Nobel Prize in Physics, which they shared with Henri Becquerel.
A second daughter, Ève, was born in 1904, but in 1906 Pierre died following a road accident. Marie continued her research with a professorship at the University of Paris, founding the Radium Institute – now the Curie Institute – in 1909, and in 1910 successfully isolating pure radium metal. Her work on radium and polonium led to Curie being awarded the 1911 Nobel Prize in Chemistry, making her the only person to have won Nobels in two different sciences.
After the outbreak of the First World War, Curie first created mobile x-ray units for use at the front lines, and later a radiological facility for treating injured soldiers’ wounds with radon gas.
Curie died in 1934 from aplastic anaemia, brought on by the effects of the radiation with which she’d spent her life working.
Lise Meitner was born in Vienna in 1878, and in 1905 became the second woman ever to receive a doctorate in physics from the city’s university.
Following the completion of her doctorate, she moved to Berlin and became an assistant to Max Planck. She published research on beta radiation, and, after the outbreak of the First World War, worked as a nurse handling X-ray equipment. She returned to Berlin in 1916 and continued work on isotopes with chemist Otto Hahn. In 1922 she observed what would later be named the Auger effect after Pierre Victor Auger, in which atoms eject electrons where they would usually emit photons. In 1926 she became the first woman to become a full professor of physics in Germany.
From 1934, Meitner, Otto Hahn and Fritz Strausmann carried out experiments involving bombarding uranium with neutrons, in which a number of radioactive products were generated. The team realised by 1938 that one of them was not radium as was initially thought, but barium – an element with around 100 fewer nucleons than uranium. The three had discovered nuclear fission.
Meitner was Jewish, and although her Austrian citizenship had provided her some protection while other Jewish scientists were dismissed from their posts and subsequently emigrated, this was no longer the case after Germany annexed Austria in 1938. Meitner fled the country, first to the Netherlands and then on to Sweden.
She refused an offer from the United States to work on the Manhattan Project that would create the first atomic bomb, and had a research position created for her at the University College of Stockholm. Meitner retired in 1960, after which she moved to the UK. She died in 1964 aged 89. A radioactive element first created in 1982 is named meitnerium in her honour.
Timeline of nuclear physics and radiation
1896 Henri Becquerel discovers radioactivity while carrying out work on phosphorescence.
1896 Marie Curie discovers that the rate of activity of uranium compounds depends only on the quantity of uranium. She infers that radiation is not a result of interaction between different compounds but comes from within the atom.
1897 JJ Thomson discovers the electron – an indication that the atom has an internal structure.
1898 Marie Curie and husband Pierre identify new elements – polonium and radium – and discover that thorium is also radioactive. They also coin the word “radioactivity”.
1899–1900 Ernest Rutherford and Paul Villard discover that there are three types of radiation, which are named alpha, beta and gamma.
1904 Thomson proposes the “plum pudding” model of the atom, in which negatively charged electrons were like the raisins in a positively charged “pudding”.
1905 Albert Einstein formulates the principle of mass-energy equivalence, his famous equation E = mc2.
1908–10 Rutherford, Hans Geiger and Ernest Marsden carry out an experiment involving firing alpha particles at gold foil. Although they were expected to pass right through, some of the alpha particles were reflected back towards their source.
1910 Marie Curie isolates pure radium metal.
1911 Rutherford develops his model of the atom, in which a very small, positively charged nucleus is orbited by a cloud of negatively charged electrons with extremely low masses.
1913 Niels Bohr suggests that electrons orbit the nucleus at specific, discrete energy levels. In Bohr’s model, electrons can move between energy levels, gaining or losing energy as electromagnetic radiation in the process, and chemical properties are determined by the number of electrons in the highest energy level.
1914 Marie Curie establishes mobile radiology units to take x-rays of French soldiers wounded in the First World War.
1916 Marie Curie establishes a military radiotherapy unit, using radon gas to kill diseased tissue.
1919 Rutherford becomes the first person to transmute one element into another, using alpha radiation to change nitrogen atoms into oxygen atoms and hydrogen nuclei.
1920 Rutherford recognises that the hydrogen nucleus is a building block of all nuclei and names the particle the proton.
1921 Rutherford postulates the existence of the neutron to account for the discrepancy between atoms’ masses and the number of protons they contain.
1928 George Gamow applies quantum mechanics to the problem of radioactive alpha-decay, showing how particles can quantum-tunnel through an energy barrier.
1932 James Chadwick discovers the neutron – it is produced after bombardment of beryllium with alpha particles.
1932 John Cockcroft and Ernest Walton split the atom – transforming lithium into helium.
1932 Mark Oliphant carries out the first experimental demonstration of nuclear fusion and speculates that such reactions could be the power source for stars.
1933 Leó Szilárd conceives the idea of the nuclear chain reaction, opening up the possibility of nuclear reactions as a source of energy.
1934 Differences between the masses of atoms and the total mass of their constituent particles are found to agree with Einstein’s mass-energy equivalence principle to within 1%.
1935 Hideki Yukawa proposes the strong nuclear force to explain how the nucleus holds together despite the protons within it electromagnetically repelling one another.
1936 Bohr develops the “liquid drop” model of the nucleus, in which the nucleons behave like molecules in a drop of liquid.
1938 Lise Meitner, Otto Frisch, Otto Hahn, and Fritz Strassmann carry out experiments involving bombarding uranium with neutrons and discover nuclear fission of heavy elements. Meitner and Frisch develop a theory of how fission occurs.
1938 Hans Bethe and Charles Critchfield work out the details of nuclear fusion in stars.
1939 Bohr and John Wheeler use the liquid drop model to explain nuclear fission as a distortion of the nucleus into a dumbbell shape, which then pinches off.
1939 Szilárd and Enrico Fermi discover neutron multiplication in uranium, showing that the element can be used to create a self-sustaining nuclear chain reaction.
1945 The first weapon to utilise nuclear fission is tested in New Mexico.
1956 The first commercial nuclear power station opens at Calder Hall, Sellafield.