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Pier CuriePhysicist
Date of Birth: 15.05.1859
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Biography of Pierre Curie
French physicist and pioneer researcher of radioactivityEarly Life and Education
Pierre Curie, a French physicist, was born in Paris. He was the younger of two sons of physician Eugène Curie and Sophie-Clé (Depouilly) Curie. His father decided to provide him with home education, as Pierre was an independent and reflective child. Pierre proved to be a diligent student and at the age of sixteen, in 1876, he obtained a bachelor's degree from the University of Paris (Sorbonne). Two years later, he earned a licentiate degree, equivalent to a master's degree, in physical sciences. In 1878, Curie became a demonstrator in the physics laboratory at Sorbonne, where he began studying the nature of crystals. Together with his elder brother Jacques, who worked in the university's mineralogical laboratory, Pierre conducted intensive experimental research in this field. The Curie brothers discovered piezoelectricity, the ability of certain crystals to generate electric charges when subjected to external forces. They also discovered the inverse effect, where these crystals undergo compression under the influence of an electric field. By applying alternating current to such crystals, they were able to make them vibrate at ultrasonic frequencies, emitting sound waves beyond human hearing. These crystals became essential components of radio equipment, such as microphones, amplifiers, and stereo systems. The Curie brothers also developed a laboratory instrument called the piezoelectric quartz balance, which produces an electric charge proportional to the applied force. It can be considered a precursor to the main components and modules of modern quartz clocks and radio transmitters. In 1882, upon the recommendation of English physicist William Thomson, Curie was appointed as the head of the laboratory at the new Municipal School of Industrial Physics and Chemistry. Despite the modest salary at the school, Curie remained the head of the laboratory for twenty-two years. After a year of being appointed as the head of the laboratory, the collaboration between the Curie brothers ceased, as Jacques left Paris to become a professor of mineralogy at the University of Montpellier. From 1883 to 1895, Curie carried out a significant series of works mainly on crystal physics. His articles on the geometric symmetry of crystals remain important for crystallographers to this day. From 1890 to 1895, Curie studied the magnetic properties of substances at different temperatures. Based on a large number of experimental data, his doctoral dissertation established the relationship between temperature and magnetization, later known as Curie's law. While working on his dissertation, Curie met Maria Skłodowska (Marie Curie), a young Polish student of the Faculty of Physics at Sorbonne, in 1894. They got married in July 1895, a few months after Pierre defended his doctoral dissertation. In 1897, shortly after the birth of their first child, Marie Curie began her research on radioactivity, which soon captured Pierre's attention until the end of his life.

Contributions to Radioactivity Research
In 1896, Henri Becquerel discovered that uranium compounds constantly emit radiation capable of exposing a photographic plate. Choosing this phenomenon as the topic of her doctoral dissertation, Marie investigated whether other compounds emit "Becquerel rays." Since Becquerel found that the radiation emitted by uranium increases the conductivity of air near the samples, Marie used the piezoelectric quartz balance developed by the Curie brothers to measure the conductivity. Soon, Marie Curie concluded that only uranium, thorium, and their compounds emit Becquerel rays, which she later named radioactivity. At the beginning of her research, Marie made an important discovery: pitchblende (uranium ore) electrifies the surrounding air much more strongly than the uranium and thorium compounds it contains, and even more than pure uranium. Based on this observation, she inferred the existence of another highly radioactive element in pitchblende that was not yet known. In 1898, Marie Curie reported the results of her experiments to the French Academy of Sciences. Convinced that his wife's hypothesis was not only true but also significant, Pierre abandoned his own research to assist Marie in isolating the elusive element. From then on, the interests of the Curie couple as researchers merged so completely that even in their laboratory notes, they always used the pronoun "we." Curie set out to separate pitchblende into its chemical components. After painstaking operations, they obtained a small amount of substance with the highest radioactivity. It turned out that this portion contained not one, but two unknown radioactive elements. In July 1898, the Curies published the article "Sur une substance radioactive contenue dans la pecelende" ("On a radioactive substance contained in pitchblende"), in which they reported the discovery of one of the elements, named polonium in honor of Marie Curie's homeland. In December, they announced the discovery of the second element, which they named radium. Both new elements were thousands of times more radioactive than uranium or thorium, constituting one millionth of pitchblende. In order to extract radium from the ore in sufficient quantity to determine its atomic weight, Curie processed several tons of pitchblende over the next four years. Working in primitive and hazardous conditions, they conducted chemical separation operations in large vats set up in a leaky shed, and all analyses were performed in the tiny, poorly equipped laboratory of the Municipal School. In September 1902, the Curies announced that they had managed to extract one-tenth of a gram of radium chloride and determine the atomic mass of radium, which turned out to be 225. (They were unable to isolate polonium since it turned out to be a product of radium decay.) Radium chloride emitted a bluish glow and heat. This visually striking substance caught the attention of the world. Recognition and awards for its discovery came almost immediately. The Curies published a vast amount of information on radioactivity they had collected during their research: from 1898 to 1904, they released thirty-six papers. Even before completing their own research, the Curies inspired other physicists to investigate radioactivity. In 1903, Ernest Rutherford and Frederick Soddy hypothesized that radioactive emissions were associated with the decay of atomic nuclei. As radioactive nuclei decay (losing some of their constituent particles), they undergo transmutation into other elements. The Curies were among the first to understand that radium could also be used for medical purposes. Observing the effects of radiation on living tissues, they suggested that radium preparations could be useful in treating tumor diseases. The Swedish Royal Academy of Sciences awarded the Curies half of the Nobel Prize in Physics in 1903 "in recognition... of their joint research on the radiation phenomena discovered by Professor Henri Becquerel," with whom they shared the prize. The Curies were ill and could not attend the award ceremony. In his Nobel Lecture, delivered two years later, Curie pointed out the potential danger posed by radioactive substances if they fell into the wrong hands and added that he belonged to those who, like Nobel, believed that new discoveries would bring more harm than good to humanity. Radium, a naturally occurring element, is extremely rare, and its prices skyrocketed considering its medical value. The Curies lived in poverty, and the lack of funds could not but affect their research. However, they firmly rejected a patent for their extraction method, as well as the prospects of commercial use of radium. According to their beliefs, this would contradict the spirit of science - the free exchange of knowledge. Despite depriving them of considerable profit, the financial situation of the Curies improved after receiving the Nobel Prize and other awards.

Later Life and Legacy
In October 1904, Curie was appointed as a professor of physics at Sorbonne, and Marie Curie became the head of the laboratory, previously led by her husband. In December of the same year, their second daughter was born. Increased income, improved funding for research, plans for the creation of a new laboratory, and the admiration and recognition of the global scientific community were supposed to make the subsequent years fruitful for the Curie couple. However, like Becquerel, Curie passed away too soon, before being able to enjoy triumph and accomplish his plans. On a rainy day, April 19, 1906, while crossing the street in Paris, he slipped and fell. His head was crushed by the wheel of a passing horse-drawn carriage, and he died instantly. Marie Curie inherited his position as a professor at Sorbonne, where she continued her research on radium. In 1910, she managed to isolate pure metallic radium, and in 1911, she was awarded the Nobel Prize in Chemistry. In 1923, Marie published a biography of Curie. Their elder daughter, Irène (Irène Joliot-Curie), shared the Nobel Prize in Chemistry in 1935 with her husband, and their younger daughter, Ève, became a concert pianist and a biographer of her mother.

Curie was a serious, reserved individual, entirely focused on his work. However, he was also a kind and compassionate person. He had a considerable reputation as an amateur naturalist and enjoyed walking or cycling as his favorite pastime. Despite his busy schedule in the laboratory and family responsibilities, the Curies always found time for joint walks. In addition to the Nobel Prize, Curie received several other awards and honorary titles, including the Davy Medal of the London Royal Society (1903) and the Matteucci Medal of the Italian National Academy of Sciences (1904). He was elected to the French Academy of Sciences in 1905.