(15 May 1859 – 19 April 1906) was a French physicist and chemist, and a pioneer in crystallography and magnetism. He shared one half of the 1903 Nobel Prize in Physics with his wife, Marie Curie, for their work on radioactivity. With their win, the Curies became the first married couple to win a Nobel Prize, launching the Curie family legacy of five Nobel Prizes.
Education and career
Pierre Curie was born on 15 May 1859 in Paris, the son of Eugène Curie (1827–1910), a doctor of Huguenot origin from Alsace, and Sophie-Claire Depouilly (1832–1897). He was educated by his father, and in his early teens showed a strong aptitude for mathematics and geometry.
In 1878, Curie earned his License in Physics from the Faculty of Sciences at the University of Paris, and worked as a laboratory demonstrator until 1882, when he joined the faculty at ESPCI Paris.
In 1895, Curie received his D.Sc. from the University of Paris and was appointed Professor of Physics. In 1900, he was promoted to Professor in the Faculty of Sciences, and in 1904 became Titular Professor.
Research
Piezoelectricity
In 1880, Pierre and his older brother, Jacques, demonstrated that an electric potential was generated when crystals were compressed, i.e. piezoelectricity. To aid this work, they invented the piezoelectric quartz electrometer. In 1881, they demonstrated the reverse effect; that crystals could be made to deform when subject to an electric field. In subsequent work on magnetism, he defined the Curie scale. This work also involved delicate equipment – balances, electrometers, etc.
Magnetism
thumb|left|Propriétés magnétiques des corps à diverses temperatures <br />(Curie's dissertation, 1895)
Before his famous doctoral studies on magnetism, Curie designed and perfected an extremely sensitive torsion balance for measuring magnetic coefficients. Variations on this equipment were commonly used by future workers in that area. He studied ferromagnetism, paramagnetism, and diamagnetism for his doctoral thesis, and discovered the effect of temperature on paramagnetism which is now known as Curie's law. The material constant in Curie's law is known as the Curie constant. He also discovered that ferromagnetic substances exhibited a critical temperature transition, above which the substances lost their ferromagnetic behavior. This is now known as the Curie temperature. The Curie temperature is used to study plate tectonics, treat hypothermia, measure caffeine, and to understand extraterrestrial magnetic fields. The curie is a unit of measurement (3.7 × 10<sup>10</sup> decays per second or 37 gigabecquerels) used to describe the intensity of a sample of radioactive material and was named after Marie and Pierre Curie by the Radiology Congress in 1910.
Curie's principle
Curie formulated what is now known as the Curie Dissymmetry Principle: a physical effect cannot have a dissymmetry absent from its efficient cause. For example, a random mixture of sand in zero gravity has no dissymmetry (it is isotropic). Introduce a gravitational field, and there is a dissymmetry because of the direction of the field. Then the sand grains can 'self-sort' with the density increasing with depth. But this new arrangement, with the directional arrangement of sand grains, actually reflects the dissymmetry of the gravitational field that causes the separation.
Radioactivity
thumb|Pierre and [[Marie Curie in the laboratory.]]
Curie worked with his wife in isolating polonium and radium. They were the first to use the term radioactivity, and were pioneers in its study. Their work, including Marie Curie's celebrated doctoral work, made use of a sensitive piezoelectric electrometer constructed by Pierre and his brother Jacques Curie. Curie's 26 December 1898 publication with his wife and M. G. Bémont for their discovery of radium and polonium was honored by a Citation for Chemical Breakthrough Award from the Division of History of Chemistry of the American Chemical Society presented to the ESPCI ParisTech (officially the École supérieure de physique et de Chimie industrielles de la Ville de Paris) in 2015. In 1903, to honor the Curies' work, the Royal Society invited Pierre to present their research. Marie was not permitted to give the lecture, so Lord Kelvin sat beside her while Pierre spoke on their research. After this, Kelvin held a luncheon for Pierre. In 1903, Pierre and Marie Curie, as well as Henri Becquerel, were awarded the Nobel Prize in Physics for their research on radioactivity.
Curie and one of his students, Albert Laborde, made the first discovery of nuclear energy, by identifying the continuous emission of heat from radium particles. Curie also investigated the radiation emissions of radioactive substances, and through the use of magnetic fields was able to show that some of the emissions were positively charged, some were negative and some were neutral. These correspond to alpha, beta, and gamma radiation.
Spiritualism
In the late nineteenth century, Curie was investigating the mysteries of ordinary magnetism when he became aware of the spiritualist experiments of other French scientists, such as Charles Richet and Camille Flammarion. He initially thought the systematic investigation into the paranormal could help with some unanswered questions about magnetism. He wrote to Marie, then his fiancée: "I must admit that those spiritual phenomena intensely interest me. I think they are questions that deal with physics."
Family
Pierre Curie's grandfather, Paul Curie (1799–1853), a doctor of medicine, was a committed Malthusian humanist and married Augustine Hofer, daughter of Jean Hofer and great-granddaughter of Jean-Henri Dollfus, great industrialists from Mulhouse in the second half of the 18th century and the first part of the 19th century.
Through this paternal grandmother, Pierre Curie is also a direct descendant of the Basel scientist and mathematician Jean Bernoulli (1667–1748), as is Pierre-Gilles de Gennes, winner of the 1991 Nobel Prize in Physics.
thumb|upright|left|Pierre and [[Marie Skłodowska-Curie, 1895.]]
Curie was introduced to Maria Skłodowska by their friend, physicist Józef Wierusz-Kowalski. Curie took her into his laboratory as his student. His admiration for her grew when he realised that she would not inhibit his research. He began to regard Skłodowska as his muse. She refused his initial proposal, but finally agreed to marry him on 26 July 1895.