World's Greatest Scientists

• Born: 780 AD, Khwarezm
• Died: 850 AD, Baghdad, Iraq
• Nationality: Iranian
• Books: The Compendious Book on Calculation by Completion and Balancing

Abū ʿAbdallāh Muḥammad ibn Mūsā al-Khwārizmī (Arabic: عَبْدَالله مُحَمَّد بِن مُوسَى اَلْخْوَارِزْمِي‎), earlier transliterated as Algoritmi or Algaurizin, (c. 780, Khwārizm – c. 850) was a Persian mathematician, astronomer and geographer during the Abbasid Empire, a scholar in the House of Wisdom in Baghdad.

In the twelfth century, Latin translations of his work on the Indian numerals introduced the decimal positional number system to the Western world. His Compendious Book on Calculation by Completion and Balancing presented the first systematic solution of linear and quadratic equations in Arabic. In Renaissance Europe, he was considered the original inventor of algebra, although it is now known that his work is based on older Indian or Greek sources. He revised Ptolemy's Geography and wrote on astronomy and astrology.

Some words reflect the importance of al-Khwarizmi's contributions to mathematics. "Algebra" is derived from al-jabr, one of the two operations he used to solve quadratic equations. Algorism and algorithm stem from Algoritmi, the Latin form of his name. His name is also the origin of (Spanish) guarismo and of (Portuguese) algarismo, both meaning digit.

• Born: July 1, 965 AD, Basra, Iraq
• Died: March 6, 1040, Cairo, Egypt
• Full name: Abu Ali al-Ḥasan ibn al-Ḥasan ibn al-Haytham
• Books: Book of Optics

Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham (Arabic: ابن الهيثم, Arabic: أبو علي، الحسن بن الحسن بن الهيثم‎, Latinized: Alhacen or (deprecated) Alhazen) (965 in Basra – c. 1040 in Cairo) was a Muslim scientist, polymath, mathematician, astronomer and philosopher, described in various sources as either an Arab or Persian. He made significant contributions to the principles of optics, as well as to astronomy, mathematics, visual perception, and to the scientific method. He also wrote insightful commentaries on works by Aristotle, Ptolemy, and the Greek mathematician Euclid.

He is frequently referred to as Ibn al-Haytham, and sometimes as al-Basri (Arabic: البصري), after his birthplace in the city of Basra. He was also nicknamed Ptolemaeus Secundus ("Ptolemy the Second") or simply "The Physicist" in medieval Europe.

Born circa 965, in Basra, present-day Iraq, he lived mainly in Cairo, Egypt, dying there at age 74. According to one version of his biography, overconfident about practical application of his mathematical knowledge, he assumed that he could regulate the floods of the Nile. After being ordered by Al-Hakim bi-Amr Allah, the sixth ruler of the Fatimid caliphate, to carry out this operation, he quickly perceived the impossibility of what he was attempting to do. Fearing for his life, he feigned madness and was placed under house arrest, during which he undertook scientific work. After the death of Al-Hakim he was able to prove that he was not mad, and for the rest of his life he made money copying texts while writing mathematical works and teaching. He is known as the "Father of Modern Optics, Experimental physics and Scientific methodology" and could be regarded as the first theoretical physicist.

• Born: April 15, 1452, Vinci, Italy
• Died: May 2, 1519, Amboise, France
• Full name: Leonardo di ser Piero da Vinci
• Period: High Renaissance
• Buried: Chapel of Saint-Hubert

Leonardo di ser Piero da Vinci (April 15, 1452 – May 2, 1519) was an Italian Renaissance polymath: painter, sculptor, architect, musician, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist, and writer. His genius, perhaps more than that of any other figure, epitomized the Renaissance humanist ideal. Leonardo has often been described as the archetype of the Renaissance Man, a man of "unquenchable curiosity" and "feverishly inventive imagination". He is widely considered to be one of the greatest painters of all time and perhaps the most diversely talented person ever to have lived. According to art historian Helen Gardner, the scope and depth of his interests were without precedent and "his mind and personality seem to us superhuman, the man himself mysterious and remote". Marco Rosci states that while there is much speculation about Leonardo, his vision of the world is essentially logical rather than mysterious, and that the empirical methods he employed were unusual for his time.

Born out of wedlock to a notary, Piero da Vinci, and a peasant woman, Caterina, in Vinci in the region of Florence, Leonardo was educated in the studio of the renowned Florentine painter, Verrocchio. Much of his earlier working life was spent in the service of Ludovico il Moro in Milan. He later worked in Rome, Bologna and Venice, and he spent his last years in France at the home awarded him by Francis I.

Leonardo was, and is, renowned primarily as a painter. Among his works, the Mona Lisa is the most famous and most parodied portrait and The Last Supper the most reproduced religious painting of all time, with their fame approached only by Michelangelo's The Creation of Adam. Leonardo's drawing of the Vitruvian Man is also regarded as a cultural icon, being reproduced on items as varied as the euro coin, textbooks, and T-shirts. Perhaps fifteen of his paintings survive, the small number because of his constant, and frequently disastrous, experimentation with new techniques, and his chronic procrastination. Nevertheless, these few works, together with his notebooks, which contain drawings, scientific diagrams, and his thoughts on the nature of painting, compose a contribution to later generations of artists rivalled only by that of his contemporary, Michelangelo.

Leonardo is revered for his technological ingenuity. He conceptualised flying machines, a tank, concentrated solar power, an adding machine, and the double hull, also outlining a rudimentary theory of plate tectonics. Relatively few of his designs were constructed or were even feasible during his lifetime, but some of his smaller inventions, such as an automated bobbin winder and a machine for testing the tensile strength of wire, entered the world of manufacturing unheralded. He made important discoveries in anatomy, civil engineering, optics, and hydrodynamics, but he did not publish his findings and they had no direct influence on later science.

Born: May 11, 1918, Manhattan, New York City, New York, United States
Died: February 15, 1988, Los Angeles, California, United States
Children: Carl Feynman, Michelle Louise Feynman
Spouse: Gweneth Howarth (m. 1960–1988), Mary Louise Bell (m. 1952–1956), Arline Greenbaum (m. 1942–1945)
Movies: Infinity, Anti-Clock, Genghis Blues


Richard Phillips Feynman (May 11, 1918 – February 15, 1988) was an American theoretical physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics (he proposed the parton model). For his contributions to the development of quantum electrodynamics, Feynman, jointly with Julian Schwinger and Sin-Itiro Tomonaga, received the Nobel Prize in Physics in 1965. He developed a widely used pictorial representation scheme for the mathematical expressions governing the behavior of subatomic particles, which later became known as Feynman diagrams. During his lifetime, Feynman became one of the best-known scientists in the world. In a 1999 poll of 130 leading physicists worldwide by the British journal Physics World he was ranked as one of the ten greatest physicists of all time.

He assisted in the development of the atomic bomb during World War II and became known to a wide public in the 1980s as a member of the Rogers Commission, the panel that investigated the Space Shuttle Challenger disaster. In addition to his work in theoretical physics, Feynman has been credited with pioneering the field of quantum computing and introducing the concept of nanotechnology. He held the Richard Chace Tolman professorship in theoretical physics at the California Institute of Technology.

Feynman was a keen popularizer of physics through both books and lectures, notably a 1959 talk on top-down nanotechnology called There's Plenty of Room at the Bottom, and the three-volume publication of his undergraduate lectures, The Feynman Lectures on Physics. Feynman also became known through his semi-autobiographical books Surely You're Joking, Mr. Feynman! and What Do You Care What Other People Think? and books written about him, such as Tuva or Bust!

• Born: June 26, 1824, Belfast, United Kingdom
• Died: December 17, 1907, Largs, United Kingdom
• Full name: William Thomson
• Awards: Copley Medal, Royal Medal, John Fritz Medal, Smith's Prize for Examination Performance
• Education: Peterhouse, Cambridge (1841–1845), University of Glasgow, Royal Belfast Academical Institution

William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, (26 June 1824 – 17 December 1907) was an Irish and British mathematical physicist and engineer who was born in Belfast in 1824. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging discipline of physics in its modern form. He worked closely with mathematics professor Hugh Blackburn in his work. He also had a career as an electric telegraph engineer and inventor, which propelled him into the public eye and ensured his wealth, fame and honour. For his work on the transatlantic telegraph project he was knighted by Queen Victoria, becoming Sir William Thomson. He had extensive maritime interests and was most noted for his work on the mariner's compass, which had previously been limited in reliability.

Lord Kelvin is widely known for determining the correct value of absolute zero as approximately -273.15 Celsius. The existence of a lower limit to temperature was known prior to Lord Kelvin, as shown in "Reflections on the Motive Power of Heat", published by Sadi Carnot in French in 1824, the year of Lord Kelvin's birth. "Reflections" used -267 as an estimate of the absolute zero temperature. Absolute temperatures are stated in units of kelvin in his honour.

On his ennoblement in 1892 in honour of his achievements in thermodynamics, and of his opposition to Irish Home Rule, he adopted the title Baron Kelvin, of Largs in the County of Ayr and is therefore often described as Lord Kelvin. He was the first UK scientist to be elevated to the House of Lords. The title refers to the River Kelvin, which flows close by his laboratory at the University of Glasgow. His home was the imposing red sandstone mansion Netherhall, in Largs on the Firth of Clyde. Despite offers of elevated posts from several world renowned universities Lord Kelvin refused to leave Glasgow, remaining Professor of Natural Philosophy for over 50 years, until his eventual retirement from that post. The Hunterian Museum at the University of Glasgow has a permanent exhibition on the work of Lord Kelvin including many of his original papers, instruments and other artefacts such as his smoking pipe.

Always active in industrial research and development, he was recruited around 1899 by George Eastman to serve as vice-chairman of the board of the British company Kodak Limited, affiliated with Eastman Kodak.

• Born: 287 BC, Syracuse, Italy
• Full name: Archimedes of Syracuse
• Nationality: Greek
• Assassinated: 212 BC, Syracuse, Italy
• Parents: Phidias

Archimedes of Syracuse (287 BC – c.212 BC) was a Greek mathematician, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Among his advances in physics are the foundations of hydrostatics, statics and an explanation of the principle of the lever. He is credited with designing innovative machines, including siege engines and the screw pump that bears his name. Modern experiments have tested claims that Archimedes designed machines capable of lifting attacking ships out of the water and setting ships on fire using an array of mirrors.

Archimedes is generally considered to be the greatest mathematician of antiquity and one of the greatest of all time. He used the method of exhaustion to calculate the area under the arc of a parabola with the summation of an infinite series, and gave a remarkably accurate approximation of pi. He also defined the spiral bearing his name, formulae for the volumes of solids of revolution, and an ingenious system for expressing very large numbers.

Archimedes died during the Siege of Syracuse when he was killed by a Roman soldier despite orders that he should not be harmed. Cicero describes visiting the tomb of Archimedes, which was surmounted by a sphere inscribed within a cylinder. Archimedes had proven that the sphere has two thirds of the volume and surface area of the cylinder (including the bases of the latter), and regarded this as the greatest of his mathematical achievements.

Unlike his inventions, the mathematical writings of Archimedes were little known in antiquity. Mathematicians from Alexandria read and quoted him, but the first comprehensive compilation was not made until c. 530 AD by Isidore of Miletus, while commentaries on the works of Archimedes written by Eutocius in the sixth century AD opened them to wider readership for the first time. The relatively few copies of Archimedes' written work that survived through the Middle Ages were an influential source of ideas for scientists during the Renaissance, while the discovery in 1906 of previously unknown works by Archimedes in the Archimedes Palimpsest has provided new insights into how he obtained mathematical results.

• Born: October 7, 1885, Copenhagen, Denmark
• Died: November 18, 1962, Copenhagen, Denmark
• Nationality: Danish
• Awards: Nobel Prize in Physics, Copley Medal, Max Planck Medal, More
• Education: University of Copenhagen (1911), More
• Children: Aage Bohr, Ernest Bohr, Hans Henrik Bohr, Erik Bohr, Christian Bohr, Harald Bohr

Niels Henrik David Bohr (7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research.

Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete, and that the electrons revolve in stable orbits around the atomic nucleus, but can jump from one energy level (or orbit) to another. Although the Bohr model has been supplanted by other models, its underlying principles remain valid. He conceived the principle of complementarity: that items could be separately analysed in terms of contradictory properties, like behaving as a wave or a stream of particles. The notion of complementarity dominated Bohr's thinking on both science and philosophy.

Bohr founded the Institute of Theoretical Physics at the University of Copenhagen, now known as the Niels Bohr Institute, which opened in 1920. Bohr mentored and collaborated with physicists including Hans Kramers, Oskar Klein, George de Hevesy and Werner Heisenberg. He predicted the existence of a new zirconium-like element, which was named hafnium, after the Latin name for Copenhagen, where it was discovered. Later, the element bohrium was named after him.

During the 1930s, Bohr helped refugees from Nazism. After Denmark was occupied by the Germans, he had a famous meeting with Heisenberg, who had become the head of the German nuclear energy project. In September 1943, word reached Bohr that he was about to be arrested by the Germans, and he fled to Sweden. From there, he was flown to Britain, where he joined the British Tube Alloys nuclear weapons project, and was part of the British mission to the Manhattan Project. After the war, Bohr called for international cooperation on nuclear energy. He was involved with the establishment of CERN and the Research Establishment Risø of the Danish Atomic Energy Commission, and became the first chairman of the Nordic Institute for Theoretical Physics in 1957.