Sir Isaac Newton 1642 –1727. Lucasian Professor. There is a vast literature on this great scientific genius and the many aspects of his life. These range from the invention of the Calculus, experiments showing the composite nature of white light, making his own reflecting telescope, to his major work the ‘Principia’ which covers the whole field of theoretical physics as then known, from the laws of motion, planetary orbits, comets, the tides of motion in resistive media. His last publication was ‘Opticks’ an account of the experiments he made fifty years previously, and ending with an intriguing set of ‘Queries’ in which he speculates on atomic structure, and other then doubtful hypotheses.

John Ray 1627 – 1705. Fellow of Trinity, lecturer In Greek, Mathematic and Humanities. John Ray was a great pioneer in the collection and classification of plants, animals, fishes, birds and even dialects and proverbs. In the classification of plants he was forerunner of Linnaes. His most famous work ‘The Wisdom of God manifested in the Works of the Creation’ was a classic of natural history.

Charles Babbage 1791 – 1871. Lucasian Professor. Charles Babbage was a great advocate of reform in mathematics and its application in technology. Whilst still n undergraduate at trinity he started an Analytical Society to replace the Newtonian method f ‘Fluxions’ by he differential method of Leibnitz which had ed to rapid progress in theoretical physics on the Continent. For applications of mathematics in technology accurate tables of mathematical function were essential. He devised his Difference Engine to enable these tables to be calculated quickly and accurately. The Analytical Engine was a more advanced machine, which could be programmed to make a wide variety of calculations. Unfortunately he never managed to complete these projects, due to lack of support.

Charles Darwin 1809 – 1882. Darwin may be regarded as the Newton of biological science, because he discovered the basic laws in this field. His formal university education – two years of medical studies at Edinburgh, three years at Cambridge – was largely irrelevant. What was important was the time he devoted to field work in natural history and geology. This gave him a reputation as a naturalist and led to friendships with leading figures in biology and geology, and thus to his appointment as naturalist on the HMS ‘Beagle’. It was the careful examination of the specimens from this voyage which gradually led him to the theory of evolution by natural selection, based on the struggle for survival, and the inheritance of slight cages which increase the fitness for this struggle. He was well aware of the profound shock this theory would cause and how vigorously it would be attacked. He spent many years mustering the evidence to support it before venturing to publish. His hesitation was cut short when AR Wallace who was working in the East Indies sent him a paper for publication based on the same idea. This led to a joint publication in 1858, followed by Darwin’s major work ‘ The origin of the Species’ in 1859, and his ‘Descent of Man’ in 1871. Darwin took little part in the controversy, which followed, continuing quietly with his natural history work. His last publication on Earthworms (18810) is a charming close to such a productive life. The Darwin connection with Cambridge is much stronger than just the three year degree course. Three of his sons were important figures in the University: George was Professor of astronomy, Francis was Reader in Botany, Horace founded the Cambridge Scientific Instrument Company, while Grandson Charles, the mathematical physicist who advised Rutherford at a crucial time in Manchester, was later Master of Christ’s College.

James Clerk Maxwell 1831 –1879. First Cavendish Professor. Clerk Maxwell was born and educated in Edinburgh and later came to Cambridge to take the course in mathematics. His first research was on the theory of Saturn’s rings. He showed that such a cloud of orbiting particles could be stable. This gained him the Adam’s Prize in 1857. He then went on to professorship at Aberdeen (1856-60) and King’s College London (1860-65). During this time he developed the kinetic theory of gases along with Boltzmann in Austria, and he carried out experiments to verify the consequences of the theory. Like Boltzman he was a strong advocate of the atomic theory of matter. He then turned to electromagnetic-theory. On this he based himself on the experimental work of Faraday who had demonstrated the close relation between electric and magnetic phenomena. Faraday had envisaged electric and magnetic forces as being due to elastic ‘lines of force’ stretching between charges or magnets through the immediate space. Maxwell gave this idea a mathematical form with his concept of electric and magnetic ‘field’, which obeyed the famous Maxwell Equations’. A consequence of these equations was the possibility of electromagnetic wave, which turned out to have the same velocity of propagation as the known velocity of light. Later this encouraged Hertz to look for such waves generated by purely electrical means – radio waves. Maxwell strongly urged the experimental study of physics as a better method of teaching than the purely theoretical approach then current. I response to this the Cavendish Laboratory was established and he was made first professor in 1871 and was responsible for the design and equipment of the laboratory.

Sir JJ Thomson 1856 – 1940. Third Cavendish Professor Nobel prize, 1906. Thomson, always known as ‘J.J.’, was the third Cavendish professor after clerk Maxwell and Lord Rayleigh. His father was a poor bookseller in Manchester. J.J. was intended to be an engineer and was sent to Owen’s College (which became the university of Manchester) which had good teachers in mathematics and physics. His father’s death meant that the apprentiship fees for engineering could not be met, so J.J. switched to mathematics. He gained a scholarship to Trinity at Cambridge, was second Wrangler in the Tripos, and went on to gain a Fellowship. His early papers were in electromagnetic theory. He showed from Maxwell’s equations that a moving electric charge would acquire an increased mass from it’s motion, thus foreshadowing Einstein’s relation between mass and energy. When Lord Rayleigh resigned his professorship J.J. was appointed to succeed him in 1884 at the early age of 27. He had little experience of experimental physics, but showed a wonderful grasp of what experiments were needed, and fortunately he had very good assistants. He started research on the discharge of electricity through gasses at low pressures following on the work of Crookes and others. He studied the nature of the ‘cathode rays’, which came from the negative electrode. It had been shown that these rays were deflected by a magnetic field, but attempts to influence them by electric fields had failed, and this led to uncertainty about their nature – particles or waves? J.J. showed that if the gas pressure was low enough there was clear deflection by by electric fields. He made careful deflections o these fields and was able to show that the rays were in fact charged particles, but with a mass that was about a thousand times smaller than that of the smallest atom, hydrogen. This discovery of the electron showed that the atom was not the smallest and most elementary particle, and suggested that electrons might be building blocks from which atoms were built. J.J. went on to study the positive or ‘canal’ rays coming from th positive electrode and by similar deflection measurements succeeded in anaysing the atoms and molecules present, which led to the discovery of isotopes. His later years were mainly important as the founder of the Cambridge School of atomic physics with many of the future leaders in this field studying under him. He was made Master of Trinity in 1918, and retired from Professorship the following year although he continued to work on projects.

Lord Rutherford of Nelson 1871 – 1937. Fourth Cavendish Professor. Nobel Prize 1908. Rutherford was born in New Zealand and educated at Nelson College and Canterbury College at Christchurch where he graduated in mathematics and physics. His first research was in radio waves, recently discovered by hertz (1887). He started this work in New Zealand. He came to Cambridge in 1995 with a scholarship from the profits of th Great Exhibition of 1951. this enabled him to start work under J.J. Thomson, at the Cavendish. He at first continued his radio experiments, achieving transmission over half a mile, then a record distance. He never tried to compete with Marconi in the commercial exploitation of radio. J.J. set him to work on the X-rays discovered by Rontgen and he investigated their effect on gaseous discharges. Then in 1987 came the discovery of radioactivity by Becquerel and this provided a new field of research. In 1899 he was appointed Professor at McGill University in Montreal and there he carried out and there he carried out his main work in radioactivity. He established the nature of the radiations coming from radioactive material, namely alpha particles (Helium ions) and beta rays (electrons), but most important was his demonstration, in collaboration with F.Soddy, that radioactivity arose from the transmutation of one chemical element into another, daughter element, and that this daughter went on to transform into a grand-daughter, a chemically quite distinct element, giving rise to a whole family of elements of elements forming a radioactive series. This was the first time that such a chemical transformation had been established. For this Rutherford was awarded the Nobel priz for Chemistry in 1908. Meanwhile I 1907 he had been appointed to be professor at Manchester University, and here together with Geiger and Marsden he studied the impact of the energetic alpha particles on other elements. From these scattering experiments he was able to show that the main mass of the atom is concentrated in a minute central nucleus. This led to the first successful model of the atom proposed by Niels Bohr (1913) who was greatly influenced and encouraged by Rutherford. In further experiments with alpha particles Rutherford found evidence that the nitrogen nucleus could be disrupted by the impact of the alpha particle, emitting protons. This was the first case of an artificial disintegration. After the war Rutherford succeeded J.J.Thomson as Cavendish Professor and continued to work on nuclear disintegration – first by the alpha particles – later by artificially accelerated particles, such as protons. With Chadwick, Cockroft and Walton, Oliphant, Blackett and others he established the Cavendish as the leading research centre in nuclear and atomic physics.

C.T.R. Wilson 1869 -1959. Wilson was born at Glencorse, Midlothian, Scotland. The family moved to Manchester where ‘C.T.R’ went to school ad to Owen’s College, where he graduated in 1887. he went to Cambridge in 1888 with a scholarship, and graduated there in 1892. He started on research, but lack of funds led him to break off for a year and take teaching post. However he returned to continue under J.J. Thomson supporting himself by tutoring students. On holiday in 1894 he was on Ben Nevis and was much impressed by the optical effects produced by the sun shining through the mist. He resolved to reproduce the same effects in the laboratory. To do this he made an expansion chamber, so that the moist air could be suddenly cooled by expansion. At first the water vapor condensed on dust particles, but even after all these were removed by repeated expansions he could obtain condensation, which he thought to be due to electrically charged ions. He tested this by passing a beam of the recently discovered X-rays through the air. This provoked a dense fog of condensation. Wilson then returned to atmospheric research on electrical discharges for several years. But in 1910 he returned to the cloud chamber to see if he could use it to see the tracks of the alpha and beta particles from radioactive substances. He succeeded brilliantly and the technique he developed was used in many crucial experiments. He continued his work on atmospheric electricity, devising apparatus for measuring the total electric discharge in a lightning flash and he made many basic contributions to the understanding of atmospheric electricity. But it is his invention of the cloud chamber for which he is chiefly remembered.

Frances Crick b. 1916 and James D. Watson b.1928. Nobel Prize 1962. Crick was educated at Mill Hill School and Univerity College, London where he started research on physics, but this was interrupted by the outbreak of war. He then worked on magnetic mines at the Admiralty research establishment. After the war he decided to switch to biological research after reading Schrdinger’s book ‘What is Life? The Physical Aspects of the living Cell’. After some difficulty he secured a research post at the Strangeways Laboratory in Cambridge but he transferred in 1949 to the newly established research unit at the Cavendish on the structure of proteins of proteins under Max Perutz. J.D. Watson came from Chicago where he took a first degree in Zoology and then went to Indiana where he started work on genetics. After taking a doctorate there he went to Copehagen where he became interested in the structure of Desoxy-ribonucleic Acid (DNA). Evidence that DNA was the carrier of the genes responsible for heredity had become strong, and it was becoming clear that it’s structure was crucial to understanding genetics. When Crick and Watson met in Cambridge there was a lot of evidence from various sources on it’s chemical composition, and X-ray diffraction pattern, but nothing that was conclusive. By building models and by inspired guess work they finally managed to arrive at the double helix. All subsequent work in genetics has been foundd on this structure. Crick and Watson shared the Nobel Prize in 1962 with Maurice Wilkins who advised them on the X-ray diffraction data; Rosalind Franklin, who had taken the X-ray photographs, had died before the award.

Sir F Gowland Hopkins 1861 –1947. Nobel Prize 1929. Hopkins had a difficult and unconventional education as a research scientist. At school he did well in chemistry and English but was bored by other subjects. He started work at 17 as an insurance clerk, but soon decided he wanted to be a scientist. He was apprenticed to an analytical chemist at a pharmaceutical firm for three years. Then he had a small inheritance from his grandfather and used it to study chemistry at University College, London. He did well there and was taken on as an assistant to a leading forensic scientist while completing his B.Sc in chemistry. Then he enrolled at Guys Hospital Medical School to get a medical qualification while supporting himself by working in the laboratory on problems arising from patients. In 1894 he took his medical degree at Guy’s and remained there for another four years teaching and carrying out research, particularly on protein chemistry. In 1898 he was invited to Cambridge to join the teaching staff and carry out research. He isolated and identified some of the main amino acids and he studied the effect of feeding mice with diets containing varying proportions of various proteins. In this he found that the mice did not thrive unless this synthetic diet was supplemented by traces of milk. They needed ‘accessory food factors’ contained in the milk. These later came to be called vitamins. It was this discovery, published in 1912, which led to the award of the Nobel prize, shared with co-discoverer Christiaan Eijkman in 1929. Hopkins made several other important advances in biochemistry, but his main contribution was as leader and director of the Cambridge biochemistry laboratories, particularly after they moved to the Dunn Institute in 1925.

Antony Hewish. Professor of Radio Astronomy b. 1924. While working with Martin Ryle at the Mullard Radio Observatory at Cambridge, Hewish set up a special array of aerials to look for scintillations, that is random variations, in the radio signals coming from stars. When we look at stars with the naked eye they appear to scintillate because of variations in the earth's atmosphere. Hewish expected that radio stars would show similar scintillations because their radio signals had to pass through solar wind before reaching earth, and the solar wind is subject to variation. These studies were successful, and gave data on the solar wind as expected. Then in 1967 a new array was set up with over 2000 aerials covering about five acres. The first observations on this were made by Jocellyn Bell, who was assisting Hewish. She found a most surprising result, a regular periodic pulse of radio waves with a repetition every 1.33 seconds. Since then several hundred such 'pulsars' have been identified with periods varying from 1/3th of a second to several seconds. These pulsars are thought to be collapsed neutron stars, which spin and send out these signals like a searchlight. In 1974 a very special pulsar was found which appears to be orbiting a companion star, most likely another neutron star. Studies on this have suggested that it is losing energy by gravitational waves - the first time such waves have been verified experimentally. This should be a striking confirmation of Einstein's General Theory.

Stephen William Hawking b. 1942. Lucasian Professor Companion of Honour. Stephen Hawking is a theoretical scientist, one of the leading experts on the General Theory of Einstein, and its application to cosmology, and the problem of reconciling it with quantum theory. He has made many contributions to the theory of ‘black holes’ and to the ‘big bang’ theory of the origin of the universe. He has also had great success as a popular writer of science – notably the ‘Brief History of Time’, which has long been on the best-seller list. All this is the more remarkable as he has suffered from a very disabling form or motor-neurone disease since the 1960s.