|Featured PhysicistsIsaac NewtonLudwig BoltzmannMichael FaradayJames Clerk MaxwellAlbert EinsteinPaul Adrien Maurice DiracRichard Feynman|
Isaac Newton (1642-1727)
made fundamental advances in mathematics (essentially creating the subject of calculus, which has become a major part of the language of physics);
used a glass prism to demonstrate that white light is actually a mixture of colours;
began to consider the possibility that gravity, which obviously influenced bodies close to the Earth, might be a universal phenomenon holding the Moon in its orbit around the Earth and the Earth in its orbit around the Sun.
Following the reopening of the University, Newton returned to Trinity College where he became a Fellow in 1667. Two years later, still only 26, he was appointed Lucasian Professor of Mathematics on the recommendation of his predecessor, Isaac Barrow.
In addition to combining mathematical genius and profound physical insight, Newton also possessed practical skills. He built the furnaces in his own small laboratory in Trinity College, where he personally carried out alchemical experiments. He also constructed a novel kind of reflecting telescope, for which he was elected a Fellow of the Royal Society. However, Newton was a solitary and difficult person who has often been described as neurotic.
Newton was recalled to natural philosophy in 1684 by the young astronomer Edmond Halley who asked how a planet would move if it was attracted towards the Sun by a force that weakened in proportion to the inverse square of its distance from the Sun: in symbols,
Newton suffered another breakdown in 1693 and subsequently quit Cambridge and the academic life in favour of London and the world of affairs. He became Warden of the Mint in 1696 and successfully oversaw the introduction of a new coinage. As a consequence he was appointed to a lucrative position as Master of the Mint and devoted much of his remaining time to theology and biblical chronology. He was elected President of the Royal Society in 1703, published his last great scientific work Opticks in 1704 (based on work performed many years earlier), and was knighted in 1705. He died, in London in 1727, and is buried in Westminster Abbey.
Ludwig Boltzmann (1844-1906)
Entropy and disorder
The statistical interpretation of thermodynamics was pioneered by James Clerk Maxwell (1831-1879) and brought to fruition by the Austrian physicist Ludwig Boltzmann.
Boltzmann's contribution was vital, but had a tragic outcome. Towards the end of the nineteenth century several puzzling facts (which eventually led to quantum theory), triggered a reaction against 'materialist' science, and some people even questioned whether atoms exist. Boltzmann, whose work was based on the concept of atoms, found himself cast as their chief defender and the debates became increasingly bitter. Always prone to bouts of depression, Boltzmann came to believe that his life's work had been rejected by the scientific community, although this was far from being true. In 1906, he committed suicide. If despair over rejection, or frustration over being unable to prove his point, were contributing factors the irony would be great indeed. Soon after Boltzmann's death, clinching evidence was found for atoms, and few would ever doubt their existence again.
Michael Faraday (1791-1867)
Michael Faraday was the son of a blacksmith. Apprenticed to a bookbinder at 14, he read about science, became enthralled with the subject, secured a job as a laboratory assistant at the Royal Institution in London, and eventually rose to be the Institution's Director and one of the most accomplished experimental researchers of all time.
James Clerk Maxwell (1831-1879)
James Clerk Maxwell was the son of a Scottish laird. He studied at the Universities of Edinburgh and Cambridge and was appointed Professor of Natural Philosophy at Aberdeen at the age of 27.
Albert Einstein (1879-1955)
1905 was an extraordinary year in Einstein's life and in the progress of science. During that year he produced four of his most important papers. In the first he explained Brownian motion - the apparently random motion exhibited by pollen grains and other small particles when they are suspended in a fluid. According to Einstein, the motion is a result of the incessant bombardment of the suspended particles by molecules of the fluid. The quantitative success of this explanation established beyond reasonable doubt the existence of molecules, which until then had been questioned by many physicists. In his second 1905 paper, Einstein formulated a theory of the photoelectric effect - the liberation of electrons from a metal exposed to electromagnetic radiation. His explanation was one of the earliest applications of quantum physics and was an important step in the development of that subject. It was mainly for this piece of work that Einstein was awarded the Nobel Prize for Physics in 1921. His third and fourth 1905 papers concerned the special theory of relativity. He laid out the foundations of the subject in the third paper and in the fourth he provided a brief but eloquent justification of his famous equation E = mc2, which uses c, the speed of light in a vacuum, to relate the mass m of a body to its total energy content E.
In 1914 Einstein moved to Berlin, the main centre of scientific research in the German-speaking world, to take up a research professorship that would free him from teaching duties. He and his wife separated soon after the move, and were eventually divorced. Einstein continued to work on general relativity and in 1916 produced the first systematic treatment of the subject in a long paper entitled Die Grundlage der allgemeinen Relativätstheorie ('The foundations of general relativity theory'). The creation of general relativity was one of the greatest intellectual achievements of the twentieth century: it led on to the study of black holes and the prediction of gravitational waves, and it provided a firm basis for future investigations in cosmology - the study of the Universe as a whole. Observations carried out in 1919, during a total eclipse of the Sun, confirmed one of the key predictions of general relativity: the gravitational deflection of starlight passing close to the edge of the Sun. This quantitative success of Einstein's theory was widely reported, and did more than any other event to make Einstein into an instantly recognized icon of scientific genius.
By the early 1920s Einstein's best scientific work was done: he wrote in 1921 'Discovery in the grand manner is for young people... and hence for me is a thing of the past'. He was none the less extremely influential in the physics community and he did much to prepare the ground for many later developments. He travelled a lot, and became increasingly active in social and political causes, particularly in support of Zionism. (Many years later he was offered the presidency of Israel, which he declined.) In 1932, Einstein and his wife left Germany for good, mainly in response to growing anti-Semitism, and moved to the USA where Einstein settled as a professor at the Institute for Advanced Study in Princeton, New Jersey. Einstein eventually became an American citizen, though he also retained the Swiss citizenship he had held since his twenties. Although Einstein was a believer in peace and harmony, and eventually argued for a world government, he also recognized the dangers of Nazism and the potential power of atomic science. As a result, in 1939, he was persuaded to co-sign a letter to the American President, Franklin D. Roosevelt, warning of the possibility of atomic weapons. This is widely thought to have had a decisive effect in prompting the US government to undertake the development of the atomic bomb, though Einstein himself played no part in the project.
Although Einstein had been deeply involved in the birth of quantum physics, he became increasingly dissatisfied with the way the subject developed after the mid-1920s. He did not believe that it gave a truly fundamental account of natural phenomena. His last major contribution to the field was the development of Bose-Einstein statistics in 1925. However his name is also recalled in the Einstein-Podolsky-Rosen experiment, a 'thought experiment' proposed in 1935 in an attempt to show that quantum physics was seriously flawed. The attempt was unconvincing, but it did emphasize the gulf that separated quantum physics from the classical physics that preceded it. The other project of Einstein's later years that continues to be remembered is his search for a unified field theory that would bring together gravity and electromagnetism. He continued to work on this up to the time of his death, often with great ingenuity, but little of that work is regarded as being of enduring value. He died in Princeton in 1955.
Paul Adrien Maurice Dirac was born in Bristol, England, in 1902. His father was a Swiss-born teacher of French, his mother a librarian. Dirac's first degree, obtained at the Merchant Venturer's Technical College, was in electrical engineering, but he had no real interest in the subject and after graduating spent two years studying mathematics at the University of Bristol. In 1923 he left Bristol for Cambridge where he remained for most of his working life.
In 1971, following his retirement from Cambridge, Dirac moved to the USA where he became a professor of physics at Florida State University. He died there in 1984. Throughout his life Dirac was renowned for his economy of speech and lack of social awareness. His book Principles of Quantum Mechanics (1930) is regarded as a classic of clear and elegant exposition. When a correspondent asked him to clarify a certain result in the text, Dirac is said to have replied that he knew of no clearer way of expressing the point. No rudeness would have been intended, just an honest statement of fact. Dirac preferred to work by himself, and had few collaborators or research students.
Richard Phillips Feynman was one of the most colourful and celebrated of US physicists. He was born in New York in 1918 and educated at the Massachusetts Institute of Technology (MIT) and Princeton. From 1942 to 1945 he was involved in the atomic bomb project at Los Alamos, where he gave ample evidence of his enormous technical virtuosity as well as earning himself a reputation as a practical joker.
In 1950 Feynman moved to the California Institute of Technology (Caltech) where he remained for the rest of his life. While there, he worked on many topics, including the theory of fundamental particles, the theory of superfluidity and the nature of the forces and interactions within the atomic nucleus. He became renowned as a teacher of physics, combining profound physical insight with a very down-to-earth style. Towards the end of his life, when already ill with cancer, he was invited to join the commission investigating the in-flight explosion of the space shuttle Challenger. As part of that work he memorably demonstrated, in front of a massive TV audience, the disastrous effect of low temperature on the booster rocket's O-ring seals by dropping one of them into a glass of iced water.
Feynman will long be remembered as one of the twentieth century's greatest exponents of intuitive - yet highly rigorous - physics. The three volumes of Feynman Lectures on Physics from his Caltech years, and Feynman's autobiographical works 'Surely You're Joking Mr Feynman!' and 'What Do You Care What Other People Think?' also ensure that he will be remembered as a character of extraordinary insight, wit and charm. In 1965 Feynman shared the Nobel Prize for Physics with Julian Schwinger and Sin-itiro Tomonaga.