Having written mostly about physicists and chemists up to this point, I thought I’d turn my attention to the field of biology. This reminded me of a time in sixth grade, when I read an entire book about Charles Darwin without realizing until the end just who he was. It must have been interesting if it kept my attention for that long, so hopefully I can do his story justice as well.

Charles Darwin was born in Shrewsbury, England, in 1809. He was the fifth of six children in a wealthy and well-connected family. His grandfathers had both been Enlightenment thinkers: Josiah Wedgwood was an industrialist who advocated for the liberation of slaves, and Erasmus Darwin was a doctor who proposed in Zoonomia that species could “transmute” into other species. Darwin’s family was Christian but encouraged free thought and exploration – especially his father, who was a medical doctor. His mother died when he was eight years old.

Darwin was supposed to follow in his father’s footsteps, and so after working as his apprentice in the summer of 1825, Darwin enrolled in the highly respected University of Edinburgh School of Medicine, along with his brother Erasmus. However, he was not interested in the course material and found surgery nauseating (remember, there was no anesthesia). He did have a great interest in natural history, though, and listened to radical speakers give their ideas about the theory of transmutation. Edinburgh was welcoming to freethinkers; this radical speech may not have been accepted at Oxford or Cambridge.

After two years at Edinburgh, it became clear that Darwin was not cut out to become a physician. His father sent him instead to Christ’s College in Cambridge, where he could earn a degree that would qualify him to become a country parson. He was not particularly enthusiastic about this career path, but took the opportunity to pursue his passion of biology and natural history. Beetle-collecting was popular in Cambridge at the time, which suited Darwin perfectly; he collected with such zeal that some of his finds got published in James Stephens’s British Entomology.

Darwin formed a close relationship with the botany professor John Stevens Henslow during his time there, learning a great deal more about natural science. He was further inspired to contribute to the field by reading works by John Herschel and Alexander von Humboldt; Herschel’s work described using observation and inductive reasoning to understand natural laws, and Humboldt’s was a narrative of scientific travels. Shortly after graduating, Darwin took a course on field geology from Professor Adam Sedgwick that involved a two-week tour of northern Wales.

Darwin returned home in late August to find a letter from Henslow. In it, Henslow explained that he had recommended Darwin as a worthy “gentleman naturalist” to accompany the H.M.S. Beagle, captained by Robert FitzRoy, on a two-year surveying voyage. Darwin’s father was initially opposed to the idea, especially since he would have to pay for Darwin to go, but he allowed himself to be talked into it. After multiple delays, the H.M.S. Beagle set sail in late December 1831. Its voyage would last five years.

Darwin had plenty of time to read and think while at sea and took particular interest in Charles Lyell’s recently published Principles of Geology, which FitzRoy gave him. In it, Lyell promoted the theory of uniformitarianism, which holds that the geological forces at work now are the same ones responsible for forming Earth’s current geological features. For example, the Grand Canyon was formed not by a sudden catastrophic event, but rather by the combined effects of erosion by the Colorado River over many millions of years. This idea of gradual change accumulating over time was in Darwin’s mind during his voyage, and he saw several interesting geological features through this perspective.

Though he became quite seasick, Darwin kept meticulous notes on geological features, animal and plant species, and fossils he observed in South America, Africa, the Galapagos Islands, and the Pacific Islands. He also collected bird, plant, and fossil specimens to bring back to England, in many cases so experts could examine them. In the Galapagos Islands, Darwin noticed that the mockingbirds were similar to those in Chile and that their features differed slightly from island to island. This was the sort of evidence he would draw on for his comprehensive theory of evolution.

Upon returning to England in 1836, Darwin found naturalists to catalog his collections and began writing his observations from the voyage formally, as part of the captain’s narrative. The experts soon confirmed that many of his specimens from the Galapagos Islands were unique species, found only in the Galapagos. Darwin also met with Charles Lyell and went on to present his geological findings about South America to the Geological Society of London, in 1837. He subsequently presented his animal and plant specimens to the Zoological Society.

The ornithologist John Gould soon proclaimed that various birds Darwin had identified in the Galapagos were in fact 12 distinct species of finches; he later told Darwin that the mockingbirds he had identified from various islands were also of separate species. From this information, Darwin began formulating ideas about how species could adapt over time, sketching genealogical branches in his notebook.

Darwin’s unpublished genealogical tree sketches

Though we focus on his development of the theory of evolution, Darwin pursued a lot of other scientific work over the years. In late 1837, he fell ill from overworking himself to meet unrealistic publication dates. In the meantime, he had been elected to the Geological Society; he would spend a great amount of time studying geology and marine invertebrates (especially barnacles) over the years. He remained so devoted to biological study that his eventual children accepted it as a way of life. One time when his son, George, visited a friend’s house, he asked the friend incredulously “But where does your father keep his barnacles?”

To get back to the story of evolution: Darwin was greatly interested in Thomas Malthus’s Essay on the Principle of Population, which asserted that the human population would increase geometrically and outstrip its food supply, which could only increase arithmetically. This put an idea into Darwin’s mind: clearly, if left to reproduce freely, most organisms would quickly produce staggering populations that would cover the earth. Since that doesn’t happen, there must be natural restraints on this process, such as predators and various ailments, to prevent most organisms from ever reproducing.

Darwin realized that there must be certain reasons for which organisms survived to reproduce and which didn’t; then, since offspring inherit their parents’ traits (that was all that could be gleaned from genetics at the time), those offspring would be better adapted to their environment than the previous generation. He would eventually call this process of selecting for favorable traits natural selection, and it would feature in his most famous work, On the Origin of Species by Means of Natural Selection, which he published in 1859.

Alfred Russel Wallace had sent Darwin a letter outlining essentially the same theory in 1858, and Charles Lyell and John Dalton Hooker arranged for them to present their ideas simultaneously. Darwin, who had been gathering evidence for his theory for 20 years, was able to publish On the Origin of Species the following year; Wallace was content to continue studying the geographical distribution of life.

Darwin’s main achievement with respect to evolution was actually in convincing fellow scientists that it was a strong theory; the general public already knew that evolution (or transmutation of species) was possible from earlier popular works. However, the scientific community would not accept his natural selection mechanism until twentieth-century advancements in the field of genetics.

Darwin’s theory of evolution is now known as the unifying theory of the live sciences, explaining biodiversity and connecting the various evidence of homologous structures, succession of fossil forms in the geological record, geographical distribution of life, vestigial organs, etc; it was further supported by DNA research in the mid-1900s. Darwin should also be remembered for his enduring work in the fields of geology, zoology, taxonomy, and botany. With respect to religion, he spent most of his life as a deist, believing that God had created the world and then left it to its natural processes.

Maria Skłodowska was born in Warsaw in 1867, the youngest of five siblings. Her father, Władysław, and her mother, Bronisława, were both well-known teachers who directed respected secondary schools. However, their family had lost its wealth and standing in previous generations by supporting Polish independence movements. Maria’s father, Władysław, was eventually fired by Russian superiors for his pro-Polish views and had to take lower-paying positions.

Maria excelled in school and was especially interested in her father’s subjects of math and physics. When Russian authorities removed science labs from the curriculum, Władysław brought home his lab equipment and personally taught his children science.

Władysław Skłodowska with his daughters

Tragically, Maria’s mother Bronisława died of tuberculosis when Maria was ten years old, just three years after her eldest sibling, Zofia, had died of typhus. Prior to her mother’s death, Maria had held Catholic views; however, Władysław’s atheism and the deaths in her family led her to become agnostic.

After graduating from secondary school, Maria and her sister Bronia were unable to enter the all-male University of Warsaw, and Władysław could not pay for them to travel elsewhere for college. Undeterred, the sisters became involved in Warsaw’s “Flying University” (also sometimes translated as the “Floating University”), which covertly taught female students. They also struck a deal to overcome their financial troubles: Maria would work to support her sister while she attended college in Paris, and Bronia would repay her in kind a few years later.

Maria spent the next several years working as a tutor and governess. While working for the Żorawskis, who were relatives of her father, she formed a relationship with their son, Kazimierz. He was a rising mathematician and they discussed marriage, but his parents refused on the grounds that she was poor and related to them.

Kazimierz Żorawski as a student

Kazimierz Żorawski would go on to become a professor, co-found the Kraków School of Mathematics, and contribute a great deal to Polish mathematics, both through his work and by co-founding the Polish Mathematical Society. And yet, as a professor at the Warsaw Polytechnic in 1935, he would often gaze pensively at the new statue of Maria Skłodowska in front of her Radium Institute.

Statue of Maria Skłodowska-Curie, 1935

Maria returned to Warsaw in 1889, where she continued her education at the Flying University and briefly worked at a chemical laboratory run by her cousin. By 1891, she finally had enough money to move to Paris and go to school there. Her sister Bronia had married Kazimierz Dłuski, a Polish physician and activist; Maria stayed with them when she first arrived in Paris. Soon afterward, she rented her own place closer to the University of Paris (also known as the Sorbonne), where she had enrolled. In France, she went by “Marie”.

The Sorbonne

Marie worked long hours studying and tutoring others for meager pay. She had very little money left over for food, and she suffered from hunger. Finally, in 1893, after eight years of covert education and two difficult years of studying in Paris, she earned a degree in physics. She would continue to study at the University of Paris while working at an industrial laboratory, earning a second degree in mathematics in 1894.

At about this time, she was commissioned to study magnetic properties of steel. In her search for laboratory space, Marie was introduced to the physicist Pierre Curie. He found a space for her to work, and the two of them grew close. Though she had intended to return to work in Poland, Marie found that Kraków University would not take her on because she was a woman. Instead, she returned in Paris to pursue a PhD; Pierre earned his own doctorate, becoming a professor at the Sorbonne. The two of them were married on July 26^th, 1895, and she became “Marie Curie”.

The Curies’ wedding photo

In searching for a thesis topic, Marie Curie landed on Henri Becquerel’s discovery of rays emitted from uranium. They were found to be similar to but different from Wilhelm Roentgen’s newly discovered X-rays. Using an electrometer developed by Pierre and his brother, she found that the air surrounding a uranium sample conducted electricity. Using this to measure the magnitude of the uranium rays, she found that their magnitude depended only on the mass of uranium in the sample. This led her to hypothesize that the rays were caused by the structure of the uranium atom.

After the birth of a daughter, Irene, in 1897, Marie Curie began teaching at the École Normale Supérieure for extra money. She carried out her research in a converted shed that was poorly insulated and leaked, and unfortunately she was unaware of the dangers of radiation exposure.

Two minerals she was using, pitchblende and torbernite, appeared to be more radioactive than uranium. If her hypothesis about radioactivity was correct, that would suggest that there were small quantities of another, much more radioactive substance in those minerals. After months of investigation, Curie concluded that the element thorium was also radioactive; however, she had been beaten to that discovery by two months. This did not account for the much more radioactive substance present in those minerals, though.

In early 1898, Pierre Curie dropped his own research on crystals to join his wife’s studies of radioactivity. After processing great quantities of pitchblende and separating its elements, the Curies produced a black powder approximately 330 times as radioactive as uranium. In a July 1898 paper, they announced their discovery of the new element “polonium”, named for Marie’s home country of Poland.

However, the liquid that remained after the polonium had been extracted was still extremely radioactive, so the Curies began searching for the presence of an even more radioactive element. In December 1898, they announced the discovery of “radium”, named for the Latin word for “ray”. They coined the term “radioactivity” at about this time.

To prove the existence of these elements, they attempted to isolate them from pitchblende. This was incredibly arduous and painstaking work, especially because it involved physically handling highly radioactive material. By 1902, they had isolated one-tenth of a gram of radium chloride from a ton of pitchblende and determined radium’s atomic weight. However, they also suffered from early symptoms of radiation sickness, experiencing physical exhaustion and inflamed hands.

In 1903, the University of Paris awarded Marie Curie her doctorate, but only her husband was permitted to speak about their work before the Royal Institution in London. In December of the same year, the Curies and Henri Becquerel were jointly awarded the Nobel Prize in Physics for their combined research into radioactivity. The committee was initially going to leave out Marie Curie, but an advocate for women scientists alerted Pierre to the committee’s intentions and he fought for her inclusion. Marie Curie thus became the first woman to win a Nobel Prize.

After the Curies won the Nobel Prize and Pierre received offers from other universities, the University of Paris realized it had to treat them a bit better. Pierre quickly became a professor of physics; when he asked for a proper laboratory, the university promised him one, though it wouldn’t deliver on that promise until 1906.

Sadly, Pierre Curie was killed in an accident in April 1906, when he stepped in front of a horse and buggy during a rainstorm. Marie was grief-stricken but agreed to take over his teaching position and carry on in their scientific endeavors. In doing so, she became the first female professor in the history of the University of Paris.

In 1910, Curie succeeded in isolating pure radium and defined an international standard unit for measuring radioactivity, the curie (unfortunately, the current SI unit is instead the becquerel). However, she was not elected to the French Academy of Sciences by a margin of one or two votes; the Academy would not elect a female member until 1962. The right wing press did her no favors, portraying her as an atheist foreigner in the lead-up to the vote.

A right-wing daily newspaper attacking Curie

Despite the negative press, Curie’s international reputation was rising. In 1911, she won the Nobel Prize in Chemistry, making her the first person to win two Nobel Prizes, period. Though it was awarded to her alone, she shared it with her late husband in her acceptance speech. This second Prize gave her leverage to convince the French government to fund the Radium Institute, which would be built in 1914 and would support research in chemistry, physics, and medicine. Curie was asked to return to Poland and continue her work there, but declined.

During World War I, research ground to a halt. Instead, Curie promoted the use of portable X-ray machines in treating soldiers near the frontlines; those units became known as “Little Curies.” Her 17 year old daughter, Irene, helped her implement these in the field. About one million soldiers were treated with her X-ray units; she also bought war bonds with her Nobel Prize money.

A “Little Curie” from WW I

After the war, Curie used her fame abroad to gather funds for the Radium Institute (especially in the United States, where she met President Warren G Harding). France also started treating her better; the government established a stipend for her and offered her a Legion of Honour award (which she declined), and she was elected to the French Academy of Medicine.

Marie Curie wrote a biography of her husband, Pierre Curie, in 1923. She also established a Radium Institute in Warsaw (the one her old mathematician friend would have seen), and her sister Bronia became its first director when it opened in 1932. She did not entirely welcome her newfound fame, because it took her away from her research, but she appreciated the funds it brought to her initiatives.

In 1934, Marie Curie travelled to the Sancellemoz Sanatorium in Passy, France to rest. She would die there in July of 1934 from aplastic anemia, likely caused by her decades-long exposure to radiation. In 1995, she and her husband were interred in the Panthéon in Paris with France’s greatest thinkers, she being the first woman to be interred there on her own merits.

Panthéon in Paris, France

Indeed, she is the most famous female scientist in history, and she and Linus Pauling remain the only scientists to have won Nobel Prizes in multiple fields. Her work on radioactivity provided vital insights into atomic theory and led to the discovery of many new elements. Indeed, her daughter, Irene, would go on to win a Nobel Prize in Chemistry with her husband for further synthesis of new radioactive elements. Curie’s institutes have also fostered research that has won multiple Nobel Prizes.

From all accounts, Marie Curie was also a very humble and dedicated person. She gave most of her Nobel Prize winnings to friends, family, and research associates, as well as using it to buy war bonds; she also decided to not patent the radium isolation process, allowing research to continue freely. Albert Einstein once remarked that she is the only person not to have been corrupted by fame. From what I’ve gathered, I’m inclined to agree with him.

Marie Curie in her Paris laboratory

This month, I’ll share the stories of famous scientists, starting with Galileo.

Galileo Galilei

Galileo was born in Pisa, Italy in 1564, the eldest son of musician and scholar Vincenzo Galilei. He gained an appreciation for music and science from his father, as well as a skepticism of authority. His formal education began at the age of eight; when his family moved to Florence, he was taught at a monastery near the city. He later considered becoming a priest, but his father urged him to pursue a medical degree instead.

Galileo entered the University of Pisa in 1581 for this purpose. However, he became quite interested in various other subjects, including mathematics and physics. In 1583, he noticed from the swinging of a chandelier that the time it took to swing back and forth (i.e. its period of motion) was independent of the distance it swung. He demonstrated this to himself with improvised pendula of equal length at home; raised to different initial heights, they swung with the same period of motion.

Galileo was on track to become a university professor but had to leave the University in 1585 before earning his degree, due to financial troubles. For many years, he supported himself with minor teaching positions while continuing to study and experiment with math and physics. One of those teaching positions was as an art instructor in Florence; Galileo admired the Renaissance artists of Florence and taught his students perspective and chiaroscuro (a style of contrast).

During this time, he published The Little Balance, describing a hydrostatic balance he had created. This gave him his first bit of fame in the scholarly world, and he was subsequently appointed chair of mathematics at the University of Pisa, in 1589. There, he conducted his famous experiments with falling objects and criticized Aristotelian views of motion.

His arrogance and unorthodox views led the university to let him go in 1592, whereupon he found a teaching position at the University of Padua, where he would remain for nearly two decades.

In 1604, Galileo began openly supporting the Copernican theory of heliocentrism and developed his law of universal acceleration for falling objects. It had previously been thought that heavier objects would fall faster (i.e. that acceleration depended on an object’s mass), but Galileo’s experiments disproved that theory.

Galileo learned of Dutch telescopes in 1609 and quickly improved on their design. Venetian merchants saw these telescopes as a way to spot ships at a greater distance and offered to pay Galileo to produce them; however, Galileo saw greater potential in his new creation. Using the telescopes to look out into space, he discovered that the moon was spherical, cratered, and mountainous; that Venus revolved around the Sun; and that Jupiter had orbiting moons.

Galileo’s telescope

Galileo published these findings in The Starry Messenger, and in an attempt to curry favor with Cosimo II de Medici, grand duke of Tuscany, he suggested that Jupiter’s moons be called the “Medician Stars”. I forgot to mention, he thought Jupiter’s moons were stars. Anyway, the book made him quite famous in Italy and Cosimo II actually did appoint him mathematician and philosopher of the Medicis, giving him a powerful new platform.

In the following years, Galileo published new works demonstrating further faults in the Aristotelian worldview. In Discourse on Bodies in Water, he described how objects float because of the differential between their mass and the amount of water they displace; in another work, he refuted Aristotle’s view that the sun was perfect by publishing his observations of sunspots.

When Galileo wrote a letter to a student saying that Copernican theory was compatible with Biblical teachings, the letter was made public. The Catholic Church disagreed with him, declaring heliocentrism a heretical idea and banning Copernicus’s On The Revolution of Heavenly Spheres in 1616. Pope Paul V personally warned Galileo to stop promoting Copernican theory.

From 1619 to 1623, Galileo was involved in a dispute with Father Orazio Grassi, a math professor at a Jesuit college. The dispute was originally over the nature of comets, but Galileo’s first response took care to insult the Jesuits and Grassi’s response was similarly combative. Galileo’s final retort was The Assayer, which was recognized as a masterpiece of polemical literature and also expounded upon many of Galileo’s thoughts on science itself. This is one of his quotes:

Just as The Assayer was going to the press in 1623, Cardinal Maffeo Barberini, a friend of Galileo’s, became Pope Urban VIII. Galileo swiftly decided to have the book dedicated to the new pope, who was delighted by the gesture and by the content of the book. He encouraged Galileo to continue his scientific research and to publish on it, provided that he remain neutral on Copernican theory.

In 1632, Galileo published Dialogue Concerning the Two Chief World Systems. As the title suggests, it was a dialogue between characters about heliocentrism. Pope Urban VIII had requested that Galileo remain neutral and represent the Church’s view, and Galileo partially fulfilled that wish. In the book, there are three characters: one supporting Copernican theory, one opposed to it, and one who is impartial. However, the opponent of heliocentrism is named Simplicio (i.e. simpleton) and trips over his own arguments.

Galileo’s Dialogue

The Church summoned Galileo to Rome immediately, and he spent several months before the Inquisition. Though he was generally treated with respect, the Church ultimately threatened him with torture and forced him to admit that he had been promoting heliocentrism and to renounce the theory. He is rumored to have muttered “E pur si muove” (And yet it moves) after his apology and renunciation.

He was sentenced to house arrest for the remainder of his life, during which time he formalized his early discoveries about motion. He disregarded Church orders to take no visitors and publish no work outside of Italy; he managed to have his summary of his life’s work, Two New Sciences, published in Holland. The discoveries he summarized and expounded upon in that work have earned him the title “father of modern science.”

Indeed, Galileo’s trial before the Inquisition has also gained him fame as a sort of martyr for science, especially in the minds of Enlightenment thinkers like Voltaire. Galileo’s advances in physics made Newton’s formulation of classical mechanics possible, a few decades later. Though not all of his hypotheses proved correct, Galileo certainly made great scientific advancements, especially in astronomy and physics, and was combative enough to leave us with a good story.

Galileo facing the Roman Inquistion by Cristiano Banti (1857)