Quem So Pierre E Marie Curie?
Na ciência, geralmente as mulheres são ofuscadas pelos seus pares masculinos. Mas toda regra tem sua exceção, como prova o casal Curie. Embora ambos tenham sido prestigiados com o Nobel de Física de 1903 pelas pesquisas com radioatividade, foi o nome de Marie que entrou para a história, deixando seu marido, Pierre, em segundo plano.
Nobel Prize
In view of the potential for the use of radium in medicine, factories began to be built in the USA for its large-scale production. The question came up of whether or not Marie and Pierre should apply for a patent for the production process. They were both against doing so. Pure research should be carried out for its own sake and must not become mixed up with industry’s profit motive. Researchers should be disinterested and make their findings available to everyone. Marie and Pierre were generous in supplying their fellow researchers, Rutherford included, with the preparations they had so laboriously produced. They furnished industry with descriptions of the production process.
For the physicists of Marie Curie’s day, the new discoveries were no less revolutionary. Although admittedly the world did not decay, what nevertheless did was the classical, deterministic view of the world. Radioactive decay, that heat is given off from an invisible and apparently inexhaustible source, that radioactive elements are transformed into new elements just as in the ancient dreams of alchemists of the possibility of making gold, all these things contravened the most entrenched principles of classical physics. For radioactivity to be understood, the development of quantum mechanics was required. But it should be noted that the birth of quantum mechanics was not initiated by the study of radioactivity but by Max Planck’s study of radiation from a black body in 1900. It was an old field that was not the object of the same interest and publicity as the new spectacular discoveries. It was not until 1928, more than a quarter of a century later, that the type of radioactivity that is called alpha-decay obtained its theoretical explanation. It is an example of the tunnel effect in quantum mechanics.
Marie
Marie, too, was an idealist; though outwardly shy and retiring, she was in reality energetic and single-minded. Pierre and Marie immediately discovered an intellectual affinity, which was very soon transformed into deeper feelings. In July 1895, they were married at the town hall at Sceaux, where Pierre’s parents lived. They were given money as a wedding present which they used to buy a bicycle for each of them, and long, sometimes adventurous, cycle rides became their way of relaxing. Their life was otherwise quietly monotonous, a life filled with work and study.
Fascinating new vistas were opening up. Pierre gave up his research into crystals and symmetry in nature which he was deeply involved in and joined Marie in her project. They found that the strong activity came with the fractions containing bismuth or barium. When Marie continued her analysis of the bismuth fractions, she found that every time she managed to take away an amount of bismuth, a residue with greater activity was left. At the end of June 1898, they had a substance that was about 300 times more strongly active than uranium. In the work they published in July 1898, they write, “We thus believe that the substance that we have extracted from pitchblende contains a metal never known before, akin to bismuth in its analytic properties. If the existence of this new metal is confirmed, we suggest that it should be called polonium after the name of the country of origin of one of us.” It was also in this work that they used the term radioactivity for the first time. After another few months of work, the Curies informed the l’Académie des Sciences, on December 26, 1898, that they had demonstrated strong grounds for having come upon an additional very active substance that behaved chemically almost like pure barium. They suggested the name of radium for the new element.
Epilogue
At the same time as the Curies were engaged in their arduous work, each of them had their teaching duties. From 1900 Marie had had a part-time teaching post at the École Normale Supérieur de Sèvres for girls. After thousands of crystallizations, Marie finally – from several tons of the original material – isolated one decigram of almost pure radium chloride and had determined radium’s atomic weight as 225. She presented the findings of this work in her doctoral thesis on June 25, 1903. Of the three members of the examination committee, two were to receive the Nobel Prize a few years later: Lippmann, her former teacher, in 1908 for physics, and Moissan, in 1906 for chemistry. The committee expressed the opinion that the findings represented the greatest scientific contribution ever made in a doctoral thesis.
Science, Technology and Society in the Time of Alfred Nobel. Proceedings of a Nobel Symposium. Edited by Carl Gustaf Bernhard, Elisabeth Crawford, Per Sörbom. Published for the Nobel Foundation by Pergamon Press, Oxford, 1982.
A week earlier Marie and Pierre had been invited to the Royal Institution in London where Pierre gave a lecture. Before the crowded auditorium he showed how radium rapidly affected photographic plates wrapped in paper, how the substance gave off heat; in the semi-darkness he demonstrated the spectacular light effect. He described the medical tests he had tried out on himself. He had wrapped a sample of radium salts in a thin rubber covering and bound it to his arm for ten hours, then had studied the wound, which resembled a burn, day by day. After 52 days a permanent grey scar remained. In that connection Pierre mentioned the possibility of radium being able to be used in the treatment of cancer. But Pierre’s scarred hands shook so that once he happened to spill a little of the costly preparation. Fifty years afterwards the presence of radioactivity was discovered on the premises and certain surfaces had to be cleaned.
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Introduction
Nobel Lectures including Presentation Speeches and Laureates’ Biographies, Chemistry 1901-21. Published for the Nobel Foundation in 1967 by Elsevier Publishing Company, Amsterdam-London-New York.
Becquerel’s discovery had not aroused very much attention. When, just a day or so after his discovery, he informed the Monday meeting of l’Académie des Sciences, his colleagues listened politely, then went on to the next item on the agenda. It was Röntgen’s discovery and the possibilities it provided that were the focus of the interest and enthusiasm of researchers. Becquerel himself made certain important observations, for instance that gases through which the rays passed become able to conduct electricity, but he was soon to leave this field. Marie decided to make a systematic investigation of the mysterious “uranium rays”. She had an excellent aid at her disposal – an electrometer for the measurement of weak electrical currents, which was constructed by Pierre and his brother, and was based on the piezoelectric effect.
In actual fact Pierre was ill. His legs shook so that at times he found it hard to stand upright. He was in much pain. He consulted a doctor who diagnosed neurasthenia and prescribed strychnine. And the skin on Marie’s fingers was cracked and scarred. Both of them constantly suffered from fatigue. They evidently had no idea that radiation could have a detrimental effect on their general state of health. Pierre, who liked to say that radium had a million times stronger radioactivity than uranium, often carried a sample in his waistcoat pocket to show his friends. Marie liked to have a little radium salt by her bed that shone in the darkness. The papers they left behind them give off pronounced radioactivity. If today at the Bibliothèque Nationale you want to consult the three black notebooks in which their work from December 1897 and the three following years is recorded, you have to sign a certificate that you do so at your own risk. People will have to do this for a long time to come. In fact it takes 1,620 years before the activity of radium is reduced to a half.
Missy
But as Elisabeth Crawford emphasizes in her book The Beginnings of the Nobel Institution, from the latter’s viewpoint, the awarding of the 1903 Prize for Physics was masterly. Formerly, only the Prize for Literature and the Peace Prize had obtained wide press coverage; the Prizes for scientific subjects had been considered all too esoteric to be able to interest the general public. The commotion centered on the award of the Prize to the Curies, especially Marie Curie, aroused once and for all the curiosity of the press and the public. The work of researchers was exciting, their findings fascinating.
On April 19, 1906, Pierre Curie was run over by a horse-drawn wagon near the Pont Neuf in Paris and killed. Now Marie was left alone with two daughters, Irène aged 9 and Ève aged 2. Shock broke her down totally to begin with. But even now she could draw on the toughness and perseverance that were fundamental aspects of her character. When she was offered a pension, she refused it: I am 38 and able to support myself, was her answer. She was appointed to succeed Pierre as the head of the laboratory, being undoubtedly most suitable, and to be responsible for his teaching duties. She thus became the first woman ever appointed to teach at the Sorbonne. After some months, in November 1906, she gave her first lecture. The large amphitheater was packed. As well as students, her audience included people from far and near, journalists and photographers were in attendance. Many people had expected something unusual to occur. Perhaps some manifestation of the historic occasion. When Marie entered, thin, pale and tense, she was met by an ovation. However the expectations of something other than a clear and factual lecture on physics were not fulfilled. But Marie’s personality, her aura of simplicity and competence made a great impression.
It was François Mitterrand who, before ending his fourteen-year-long presidency, took this initiative, as he said “in order to finally respect the equality of women and men before the law and in reality” (“pour respecter enfin …l’égalité des femmes et des hommes dans le droit comme dans les faits”). In point of fact – as the press pointed out – this initiative was symbolic three times over. Marie Curie was a woman, she was an immigrant and she had to a high degree helped increase the prestige of France in the scientific world.
Pierre
Some biographers have questioned whether Marie deserved the Prize for Chemistry in 1911. They have claimed that the discoveries of radium and polonium were part of the reason for the Prize in 1903, even though this was not stated explicitly. Marie was said to have been awarded the Prize again for the same discovery, the award possibly being an expression of sympathy for reasons that will be mentioned below. Actually, however, the citation for the Prize in 1903 was worded deliberately with a view to a future Prize in Chemistry. Chemists considered that the discovery and isolation of radium was the greatest event in chemistry since the discovery of oxygen. That for the first time in history it could be shown that an element could be transmuted into another element, revolutionized chemistry and signified a new epoch.
The health of both Marie and Pierre Curie gave rise to concern. Their friends tried to make them work less. All their symptoms were ascribed to the drafty shed and to overexertion. Their dearest wish was to have a new laboratory but no such laboratory was in prospect. When Paul Appell, the dean of the faculty of sciences, appealed to Pierre to let his name be put forward as a recipient for the prestigious Legion of Honor on July 14,1903, Pierre replied, “… I do not feel the slightest need of being decorated, but I am in the greatest need of a laboratory.” Although Pierre was given a chair at the Sorbonne in 1904 with the promise of a laboratory, as late as 1906 it had still not begun to be built. Pierre was given access to some rooms in a building used for study by young medical students. Pierre Curie never obtained a real laboratory.
A terrible year
Nobel Lectures including Presentation Speeches and Laureates’ Biographies, Physics 1901-21. Published for the Nobel Foundation in 1967 by Elsevier Publishing Company, Amsterdam-London-New York.
Curie’s studies of radioactive substances were made together with his wife, whom he married in 1895. They were achieved under conditions of much hardship – barely adequate laboratory facilities and under the stress of having to do much teaching in order to earn their livelihood. They announced the discovery of radium and polonium by fractionation of pitchblende in 1898 and later they did much to elucidate the properties of radium and its transformation products. Their work in this era formed the basis for much of the subsequent research in nuclear physics and chemistry. Together they were awarded half of the Nobel Prize for Physics in 1903 on account of their study into the spontaneous radiation discovered by Becquerel, who was awarded the other half of the Prize.