Scientist of the day

Meghnad Saha

Meghnad Saha FRS (6 October 1893 – 16 February 1956) was a Indian astrophysicist best known for his development of the Saha equation, used to describe chemical and physical conditions in stars.

Biography

Meghnad Saha was born in Shaoratoli village near Dhaka, British India. Son of Jagannath Saha, Meghnad Saha belonged to a poor family and struggled to rise in life. He had his initial schooling at Dhaka Collegiate School, and later moved to Dhaka College. He was also a student at the Presidency College, Kolkata; a professor at Allahabad University from 1923 to 1938, and thereafter a professor and Dean of the Faculty of Science at the University of Calcutta until his death in 1956. He became Fellow of the Royal Society in 1927. He was president of the 21st session of the Indian Science Congress in 1934.

Saha was fortunate to have brilliant teachers and class fellows. In his student days, Jagadish Chandra Bose, Sarada Prasanna Das and Prafulla Chandra Ray were at the pinnacle of their fame. Amongst his class fellows were Satyendra Nath Bose, Jnan Ghosh and J. N. Mukherjee. In later life he was close to Amiya Charan Banerjee, a renowned mathematician at Allahabad University.

On his religious views, Saha was an atheist.^[1][2]

Saha died on 16 February 1956.

Career

Meghnad Saha's best-known work concerned the thermal ionisation of elements, and it led him to formulate what is known as the Saha equation. This equation is one of the basic tools for interpretation of the spectra of stars in astrophysics. By studying the spectra of various stars, one can find their temperature and from that, using Saha's equation, determine the ionisation state of the various elements making up the star. This work was soon extended by Ralph H. Fowler and Edward Arthur Milne. Saha had previously reached the following conclusion on the subject.^[3]

"It will be admitted from what has gone before that the temperature plays the leading role in determining the nature of the stellar spectrum. Too much importance must not be attached to the figures given, for the theory is only a first attempt for quantitatively estimating the physical processes taking place at high temperature. We have practically no laboratory data to guide us, but the stellar spectra may be regarded as unfolding to us, in an unbroken sequence, the physical processes succeeding each other as the temperature is continually varied from 3000° K to 40,000° K."

Saha also invented an instrument to measure the weight and pressure of solar rays and helped to build several scientific institutions, such as the Physics Department in Allahabad University and the Institute of Nuclear Physics in Calcutta. He founded the journal Science and Culture and was the editor until his death.^[4] He was the leading spirit in organizing several scientific societies, such as the National Academy of Science (1930), the Indian Physical Society (1934), Indian Institute of Science (1935) and the Indian Association for the Cultivation of Science (1944). A lasting memorial to him is the Saha Institute of Nuclear Physics, founded in 1943 in Kolkata

Saha was also one of the prominient among the works on halley's comet.

Saha was the chief architect of river planning in India and prepared the original plan for the Damodar Valley Project. His own observation with respect to his transition into government projects and political affairs is as follows:

"Scientists are often accused of living in the "Ivory Tower" and not troubling their mind with realities and apart from my association with political movements in my juvenile years, I had lived in ivory tower up to 1930. But science and technology are as important for administration now-a-days as law and order. I have gradually glided into politics because I wanted to be of some use to the country in my own humble way."^[5]

Tributes to Saha

• "Meghnad Saha’s ionization equation (c. 1920), which opened the door to stellar astrophysics” was one of the top ten achievements of 20th century Indian science [and] could be considered in the Nobel Prize class." - Jayant Narlikar^[6]

• "The impetus given to astrophysics by Saha’s work can scarcely be overestimated, as nearly all later progress in this field has been influenced by it and much of the subsequent work has the character of refinements of Saha’s ideas." - S. Rosseland^[7]

• "He (Saha) was extremely simple, almost austere, in his habits and personal needs. Outwardly, he sometimes gave an impression of being remote, matter of fact, and even harsh, but once the outer shell was broken, one invariably found in him a person of extreme warmth, deep humanity, sympathy and understanding; and though almost altogether unmindful of his own personal comforts, he was extremely solicitous in the case of others. It was not in his nature to placate others. He was a man of undaunted spirit, resolute determination, untiring energy and dedication." - D. S. Kothari^[8]

Scientist of the day

Marie Curie

Marie Skłodowska-Curie (/ˈkjʊri, kjʊˈri/;^[2] French: [kyʁi]; 7 November 1867 – 4 July 1934) was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the first woman to win a Nobel Prize, the first person (and only woman) to win twice, the only person to win twice in multiple sciences, and was part of the Curie family legacy of five Nobel Prizes. She was also the first woman to become a professor at the University of Paris, and in 1995 became the first woman to be entombed on her own merits in the Panthéon in Paris.

She was born Maria Salomea Skłodowska (pronounced [ˈmarja salɔˈmɛa skwɔˈdɔfska]) in Warsaw, in what was then the Kingdom of Poland, part of the Russian Empire. She studied at Warsaw's clandestine Floating University and began her practical scientific training in Warsaw. In 1891, aged 24, she followed her older sister Bronisława to study in Paris, where she earned her higher degrees and conducted her subsequent scientific work. She shared the 1903 Nobel Prize in Physics with her husband Pierre Curie and with physicist Henri Becquerel. She won the 1911 Nobel Prize in Chemistry.

Her achievements included a theory of radioactivity (a term that she coined^[3]), techniques for isolating radioactive isotopes, and the discovery of two elements, polonium and radium. Under her direction, the world's first studies were conducted into the treatment of neoplasms, using radioactive isotopes. She founded the Curie Institutes in Paris and in Warsaw, which remain major centres of medical research today. During World War I, she established the first military field radiological centres.

While a French citizen, Marie Skłodowska Curie (she used both surnames)^[4][5] never lost her sense of Polish identity. She taught her daughters the Polish language and took them on visits to Poland.^[6] She named the first chemical element that she discovered – polonium, which she first isolated in 1898 – after her native country.^[a]

Curie died in 1934 at the sanatorium of Sancellemoz (Haute-Savoie), France, due to aplastic anemia brought on by exposure to radiation – including carrying test tubes of radium in her pockets during research and her World War I service in mobile X-ray units created by her.^[7]

Nobel Prizes

1903 Nobel Prize portrait

In December 1903, the Royal Swedish Academy of Sciences awarded Pierre Curie, Marie Curie, and Henri Becquerel the Nobel Prize in Physics, "in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel."^[18] At first, the Committee intended to honour only Pierre and Becquerel, but one of the committee members and an advocate of woman scientists, Swedish mathematician Magnus Goesta Mittag-Leffler, alerted Pierre to the situation, and after his complaint, Marie's name was added to the nomination.^[39] Marie was the first woman to be awarded a Nobel Prize.^[18]

Curie and her husband declined to go to Stockholm to receive the prize in person; they were too busy with their work, and Pierre, who disliked public ceremonies, was feeling increasingly ill.^[38][39] As Nobel laureates were required to deliver a lecture, the Curies finally undertook the trip in 1905.^[39] The award money allowed the Curies to hire their first laboratory assistant.^[39] Following the award of the Nobel Prize, and galvanized by an offer from the University of Geneva, which offered Pierre a position, the University of Paris gave Pierre a professorship and the chair of physics, although the Curies still did not have a proper laboratory.^[18][35][36] Upon Pierre's complaint, the University of Paris relented and agreed to furnish a new laboratory, but it would not be ready until 1906.^[39]

In December 1904, Curie gave birth to their second daughter, Ève.^[39] She later hired Polish governesses to teach her daughters her native language, and sent or took them on visits to Poland.^[6]

On 19 April 1906, Pierre was killed in a road accident. Walking across the Rue Dauphine in heavy rain, he was struck by a horse-drawn vehicle and fell under its wheels, causing his skull to fracture.^[18][40] Curie was devastated by her husband's death.^[41] On 13 May 1906 the physics department of the University of Paris decided to retain the chair that had been created for Pierre and to offer it to Marie.^[41] She accepted it hoping to create a world-class laboratory as a tribute to Pierre.^[41][42] She was the first woman to become a professor at the University of Paris.^[18]

Curie's quest to create a new laboratory did not end with the University of Paris, however. In her later years, she headed the Radium Institute (Institut du radium, now Curie Institute, Institut Curie), a radioactivity laboratory created for her by the Pasteur Institute and the University of Paris.^[42] The initiative for creating the Radium Institute had come in 1909 from Pierre Paul Émile Roux, director of the Pasteur Institute, who had been disappointed that the University of Paris was not giving Curie a proper laboratory and had suggested that she move to the Pasteur Institute.^[18][43] Only then, with the threat of Curie leaving, did the University of Paris relent, and eventually the Curie Pavilion became a joint initiative of the University of Paris and the Pasteur Institute.^[43]

In 1910 Curie succeeded in isolating radium; she also defined an international standard for radioactive emissions that was eventually named for her and Pierre: the curie.^[42] Nevertheless, in 1911 the French Academy of Sciences did not elect her to be a member by one^[18] or two votes.^[44] Elected instead was Édouard Branly, an inventor who had helped Guglielmo Marconi develop the wireless telegraph.^[45] A doctoral student of Curie, Marguerite Perey, became the first woman elected to membership in the Academy – over half a century later, in 1962. Despite Curie's fame as a scientist working for France, the public's attitude tended toward xenophobia—the same that had led to the Dreyfus affair–which also fuelled false speculation that Curie was Jewish.^[18][44] During the French Academy of Sciences elections, she was vilified by the right wing press who criticised her for being a foreigner and an atheist.^[44] Her daughter later remarked on the public hypocrisy as the French press often portrayed Curie as an unworthy foreigner when she was nominated for a French honour, but would portray her as a French hero when she received a foreign one such as her Nobel Prizes.^[18]

In 1911 it was revealed that in 1910–11 Curie had conducted an affair of about a year's duration with physicist Paul Langevin, a former student of Pierre's^[46]—a married man who was estranged from his wife.^[44] This resulted in a press scandal that was exploited by her academic opponents. Curie (then in her mid-40s) was five years older than Langevin and was misrepresented in the tabloids as a foreign Jewish home-wrecker.^[47] When the scandal broke, she was away at a conference in Belgium; on her return, she found an angry mob in front of her house and had to seek refuge, with her daughters, in the home of a friend.^[44]

1911 Nobel Prize diploma

International recognition for her work had been growing to new heights, and the Royal Swedish Academy of Sciences, overcoming opposition prompted by the Langevin scandal, honored her a second time, with the 1911 Nobel Prize in Chemistry.^[10] This award was "in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element."^[48] She was the first person to win or share two Nobel Prizes, and remains alone with Linus Pauling as Nobel laureates in two fields each. A delegation of celebrated Polish men of learning, headed by novelist Henryk Sienkiewicz, encouraged her to return to Poland and continue her research in her native country.^[10] Curie's second Nobel Prize enabled her to persuade the French government into supporting the Radium Institute, built in 1914, where research was conducted in chemistry, physics, and medicine.^[43] A month after accepting her 1911 Nobel Prize, she was hospitalised with depression and a kidney ailment.^[48] For most of 1912 she avoided public life but did spend time in England with her friend and fellow physicist, Hertha Ayrton.^[48] She returned to her laboratory only in December, after a break of about 14 months.^[48]

In 1912 the Warsaw Scientific Society offered her the directorship of a new laboratory in Warsaw but she declined, focusing on the developing Radium Institute to be completed in August 1914, and on a new street named Rue Pierre-Curie.^[43][48] She visited Poland in 1913 and was welcomed in Warsaw but the visit was mostly ignored by the Russian authorities.^[43] The Institute's development was interrupted by the coming war, as most researchers were drafted into the French Army, and it fully resumed its activities in1919

Death

1935 statue, facing the Radium Institute, Warsaw

Curie visited Poland for the last time in early 1934.^[10][62] A few months later, on 4 July 1934, she died at the Sancellemoz Sanatorium in Passy, in Haute-Savoie, from aplastic anemia believed to have been contracted from her long-term exposure to radiation.^[43][63] The damaging effects of ionising radiation were not known at the time of her work, which had been carried out without the safety measures later developed.^[62] She had carried test tubes containing radioactive isotopes in her pocket,^[64] and she stored them in her desk drawer, remarking on the faint light that the substances gave off in the dark.^[65] Curie was also exposed to X-rays from unshielded equipment while serving as a radiologist in field hospitals during the war.^[50] Although her many decades of exposure to radiation caused chronic illnesses (including near blindness due to cataracts) and ultimately her death, she never really acknowledged the health risks of radiation exposure.^[66]

She was interred at the cemetery in Sceaux, alongside her husband Pierre.^[43] Sixty years later, in 1995, in honour of their achievements, the remains of both were transferred to the Panthéon, Paris. She became the first—and so far the only—woman to be honoured with interment in the Panthéon on her own merits.^[59]

Because of their levels of radioactivity, her papers from the 1890s are considered too dangerous to handle.^[67] Even her cookbook is highly radioactive.^[67] Her papers are kept in lead-lined boxes, and those who wish to consult them must wear protective clothing.^[67]

In her last year she worked on a book, Radioactivity, which was published posthumously in 1935.