Famous Scientists

  • Home
  • Top 100 Scientists
  • List of Scientists
  • Blog

Karl Popper

Karl Popper

Lived 1902 – 1994.

Karl Popper changed the way we think about science.

Scientific theories were thought to be tested by a process of verification. Popper showed they could only be tested by falsification. If a theory can be falsified, he said, it counts as science. Otherwise, it is pseudoscience or simply outside the limits of science.

His hypothetico-deductive model of the scientific method has largely replaced the older deductive and inductive models.

Advertisements

Beginnings

Karl Raimund Popper was born in Austria’s capital city, Vienna, on July 28, 1902.

His father was Simon Siegmund Carl Popper, a wealthy, successful lawyer. His mother was Jenny Schiff, a talented amateur pianist. Both of his parents were converts from Judaism to Lutheranism. They were not religious people; they converted in order to assimilate culturally in Austrian society.

Karl was the youngest of three children; he had two older sisters, Dora and Annie. His upbringing was highly cultured: the Popper home had its own scholar’s library, and the appreciation and playing of classical music was a dependable and enjoyable part of daily life.

A Childhood of Contrasts

Despite his privileged background and his frequent visits to Vienna’s concert halls and art galleries, Karl’s main concern was the obvious poverty he saw in the city. It became a source of consistent worry to him. Later he wrote:

Karl Popper“Few people now living in one of the Western democracies know what poverty meant… men, women and children suffering from hunger, cold and hopelessness.”

Karl Popper
Unended Quest, 1976
 

His father worked with two organizations offering shelter and food to the homeless. One of these organizations gave a destitute 19-year-old by the name of Adolf Hitler a roof over his head in 1908. Karl only learned about his father’s charitable work several years later.

Scientific and Philosophical Questions

Even as a young boy, Karl thought about big questions in science and philosophy. He worried about the concept of infinity – a problem which in later life he continued to wrestle with. Influenced by Darwin’s ideas, he also began speculating about the origin of life.

An Aversion to High School

Karl found high school lessons at the Vienna Gymnasium intolerably slow and boring; he felt his time was being wasted. In 1917, age 15, he returned to school after a long illness and found that even in mathematics, the one subject he enjoyed, the class had made little progress.

In late 1918, age 16, he left school and matriculated at the University of Vienna, not to study for a degree, but simply to attend lectures he thought would be interesting and worthwhile. He did not need to pass an entrance exam to do this.

Marxism vs Einstein – Game Changer

Becoming a Marxist

World War 1 ended in November 1918, about the same time as Karl Popper matriculated at university.

Austria was on the losing side, and its people were now tormented by severe financial and social turmoil. The problems of poverty that had concerned Popper as a child were now more acute, affecting many more people.

Popper became a Marxist, and by early 1919, aged 17, he had become a Communist. He believed these doctrines offered the best means to end the terrible hardship faced by many of Vienna’s citizens.

His Communist phase was very short-lived. Popper soon concluded that Communists, with their belief in revolutionary violence, did not care about people dying: they exploited the workers cynically, using them as pawns in a power game.

Inspired by Einstein

In 1919, learning about Albert Einstein’s work changed Popper’s life.

Einstein’s general theory of relativity said that gravity was actually a curvature of space-time caused by mass. The larger the mass, the greater the curvature. The theory predicted that light from distant stars passing close to the sun would follow a gravitational curve in space-time caused by the sun’s enormous mass.

In May 1919, Arthur Eddington led an expedition to Africa to observe an eclipse of the sun. Eddington’s plan was to observe starlight passing close to the sun to see if it was deflected in agreement with Einstein’s theory. This was a crucial test of the general theory of relativity. It passed with flying colors.

What truly impressed Popper was that Einstein had expressed a willingness to discard his theory if it failed certain critical tests. For example, Einstein had written:

“If the redshift of spectral lines due to the gravitational potential should not exist, then the general theory of relativity will be untenable.”

Popper contrasted the outlook of Einstein, who was willing to set objective criteria to determine if his theory was wrong, with the outlook of his Marxist friends.

Popper believed significant flaws in the historical and economic theories of Marx had been demonstrated repeatedly, yet Marx’s followers seemed to cling to them dogmatically or cobble together new interpretations.

The Einstein vs Marx contrast was a crucial step in Popper’s intellectual development. At any rate, he decided that he would not become a party politician!

Jack of all Trades

Popper sampled lectures in a large number of subjects at the University of Vienna, continuing only with Mathematics and Theoretical Physics.

In winter 1919/20 he left home, trying not to be a burden on his parents, who had lost most of their savings in the wake of Austria’s defeat in World War 1.

While he continued his academic education, Popper also worked as an apprentice furniture maker. He qualified as a journeyman in the fall of 1924, age 22. However, he did not think he would ever make high quality furniture, because his concentration was broken too often by his obsession with epistemology – the theory of knowledge.

He became a social worker, working with disadvantaged children.

The Institute of Education, Psychology, and a Doctorate

In 1925, a new education institute opened in Vienna – the Institute of Pedagogy. Austria’s government wanted to reform the country’s education system, and a number of social workers, including Popper, were sent to the new institute to learn about theories of education and psychology. Soon, Popper began teaching there unofficially, helping his fellow students prepare for their exams.

Popper thought deeply about knowledge, education, and psychology, becoming increasingly suspicious of psychological theories.

In 1928, age 26, he was awarded a Ph.D. for a thesis entitled On the Problem of Method in the Psychology of Thinking.

In 1929, he qualified as a mathematics and physical science teacher.

Theory of Knowledge: Falsification

While working as a high school teacher, Popper returned to an issue that had obsessed him since his Einstein vs Marxism comparison back in 1919. This was the issue of demarcation – the factors that separate science from pseudoscience.

By this time he had added the psychiatric ideas of Freud and Jung to the political and economic theories of Marx as examples of pseudoscience.

In 1934, Popper published his groundbreaking book Logik der Forschung. The book was published in English in 1959 entitled The Logic of Discovery.

Popper’s work effectively killed off a branch of philosophy known as logical positivism. Followers of this philosophy believed that science is carried forward by a process of verification, in which scientists pile up ever more data, and ever more examples in support of a theory. Popper showed that scientific theories can never be wholly verified:

  • No number of sightings of white swans can prove the theory that all swans are white. The sighting of just one black one may disprove it.
  • Newton’s theory of gravitation had existed for centuries before Einstein’s replaced it.

Popper had exposed a flaw in the logical foundations of science. Since scientific theories could never be verified, they could never be tested. However, Popper also solved this problem: he demonstrated that scientific theories are actually tested by falsification, not verification.

And here lay the solution to his demarcation problem – science can be distinguished from pseudoscience by the concept of falsification using observations/experiments.

black white swans

Even if millions of white swans have been observed over many years, seeming to verify the theory that all swans are white, the observation of a single black swan falsifies that theory.

Karl Popper“The game of science is, in principle, without end. He who decides one day that scientific statements do not call for any further test, and that they can be regarded as finally verified, retires from the game.”

Karl Popper
The Logic of Scientific Discovery, 1959
 

The concept of falsification was not new. For example, in the previous century Thomas Huxley had famously referred to:

The slaying of a beautiful theory by an ugly fact.

while in the 17th century Blaise Pascal wrote:

“In order to show that a hypothesis is evident, it does not suffice that all the phenomena follow from it; instead, if it leads to something contrary to a single one of the phenomena, that suffices to establish its falsity.”

What was new was that Popper used the principle of falsification as the formal test of a scientific theory, and as the formal way in which scientific theories could be separated from pseudoscientific theories.

It would be fair to say that Popper’s model has not been universally accepted, but few ideas in philosophy are above criticism. In the words of the great French philosopher René Descartes:

René Descartes“Seeing [philosophy] had been cultivated by the most powerful minds… but nevertheless there is not in it one single thing which is not disputed, and therefore open to doubt, I had not the presumption to hope that I should succeed better than others. Considering how many different opinions there are… while it was impossible that more than one of them could be true, I regarded as little better than false everything that was merely probable.”

René Descartes
1637
 

Growth of Knowledge

Popper said that a true scientific theory must hold enough content within it to offer the opportunity to falsify it. He saw this as a Darwinian process – science evolves by a process of natural selection. Extinction occurs by falsification.

Popper considered past philosophies of human knowledge to be unproductive because they did not seem to concern themselves with what he considered the most important aspect of knowledge: its growth – the discovery of new knowledge.

He said that scientific progress is made when the content of theories increases. Naturally, the more content any theory contains, the more opportunities there are for it to be tested by falsification.

The Scientific Method

So, asked Popper, what is the scientific method? :

In a (very small) nutshell, Aristotle and Francis Bacon had previously offered ideas:

deduction, induction

Bacon’s popular inductive model was based on the belief that the scientific method consisted of:

  1. making a large number of specific observations
  2. formulating a theory that is consistent with the observations

Popper disagreed with Bacon’s model. Popper said that observations do not actually come first. It would be meaningless to make observations without having some idea about why you were making them. He argued that science actually begins with a tentative idea – it might be highly tentative – and then advances by data collection and trial and error.

Nobel Prize winning physicist Paul Dirac took a more pragmatic view of the deduction vs induction debate:

Paul Dirac“The successful development of science requires a proper balance to be maintained between the method of building up from observations and the method of deducing by pure reasoning from speculative assumptions.”

Paul Dirac
Nature, June 12, 1937
 

According to Popper, the most important thing is that whichever way a scientist arrives at a theory or hypothesis, it must be falsifiable. If a theory is not falsifiable, it is not scientific.

Popper called this the Hypothetico-deductive method. Allowing for some degree of flexibility, it is generally considered to be the model that best describes the modern scientific method.

Karl Popper“Only the falsity of the theory can be inferred from empirical evidence, and this inference is purely a deductive one.”

Karl Popper
Conjectures and Refutations, 1963
 

Popper’s Hypothetico-deductive method shares some of the concepts advanced by the nineteenth century British polymath William Whewell.

The Need for Flexibility

History shows us that flexibility is needed regarding falsification. Theories with many successes under their belt should not be abandoned too quickly. On the other hand, falsified theories should not be hung on to by continually making adjustments to them or cobbling together contentious evidence to support them.

Don’t Abandon a Successful Theory Too Quickly

Neptune

The discovery of Neptune in 1846 prevented falsification of Newton’s theory.

By 1824, Newton’s gravitational theory had apparently been falsified by observations of Uranus’s orbit. Uranus was not following the path predicted by Newton’s theory.

Scientists, however, did not abandon the theory. They produced a new falsifiable theory, that the gravity of a planet farther from the sun than Uranus was affecting Uranus’s behavior.

This theory was tested, with the result that Neptune was discovered. Newton’s theory had not been falsified; it had survived, and knowledge had grown.

Don’t Hang on to a Falsified Theory for Too Long

Although Uranus’s behavior could be explained within the framework of Newton’s theory, Mercury’s behavior could not. The closest approach of Mercury to the sun during its orbit was moving in a way that did not agree with Newtonian theory. In the rather tongue-twisting jargon of astronomers, this was the problem of the precession of the perihelion of Mercury.

Mercury's precessing perihelion.

Mercury’s precessing perihelion.

It turns out that Mercury’s behavior was actually falsifying Newton’s theory. Mercury is the planet that feels the sun’s gravity most powerfully, and therefore might be expected to act like a canary in a coalmine for any theory of gravitation.

However, Newton’s theory had proved so successful in so many instances, that people did not consider that it could be wrong. In their eyes, the verification evidence outweighed the falsification evidence.

With a view to keeping Newton’s theory alive, scientists made a number of suggestions – such as the gravity of a proposed planet called Vulcan disturbing Mercury’s orbit. An astronomer even claimed to have seen Vulcan. Most scientists did not wish to consider the need for a new theory of gravitation. They had seen so many white swans that they refused to believe the black swan was even a swan at all.

However, experimental verification of Einstein’s theory finally falsified Newton’s theory. Only time will tell if Einstein’s theory will itself be falsified.

Don’t Abandon vs Don’t Hang on

So when should an apparently falsified theory be abandoned?

Unfortunately, the answer to this question is not always obvious. Discarding a theory is a matter of judgment for the scientists carrying out the work.

Science should be Value Neutral

Popper believed that scientists should produce and experimentally test hypotheses to increase our factual knowledge about the world. Scientists should not promote theories about how the world ‘should be’ and science should not be ideologically motivated.

Science should be Imaginative and Bold

Popper encouraged scientists to put forward big, bold, challenging theories. He believed that imaginative theories, whether falsified or not, were the best means to grow human knowledge.

The Open Society

Popper’s best known work outside pure scientific philosophy is his 1945 book The Open Society and Its Enemies. In it he identified Plato, Hegel, and Marx as promoters of totalitarian government and therefore enemies of the open society. As might be expected, academics who approved of the philosophies of Plato, Hegel, and Marx leaped to their defense, accusing Popper of misinterpreting their ideas.

Popper said that although a democracy need not be an open society, liberal democracy was the best way to achieve one. Inspired by the achievements of the Ancient Greeks, he argued against tribal and collectivist societies, asserting that individuals should take responsibility for their own choices and actions.

He contended that Fascist or Communist totalitarian societies politicized science, preventing freedom of thought, leading to the degradation of knowledge. Totalitarian governments harmed people and societies by imposing policies on them that had been formulated using false theories.

Some Personal Details and the End

Popper met his wife Josefine Anna Henninger in 1925 at Institute of Education in Vienna where she was also a student. They married in 1930.

In 1937, concerned at the growth of Nazism in Germany, and correctly fearing Germany would annex Austria, Popper took up a position as a lecturer in philosophy at Canterbury University in Christchurch, New Zealand.

In 1946, he became a reader at the London School of Economics, and in 1949, he was promoted to Professor of Logic and Scientific Method.

He was knighted by Queen Elizabeth in 1965, becoming Sir Karl Popper.

In 1969, age 67, he retired from his professorship, but remained active in academic circles for the rest of his life.

He loved playing the piano, as his mother had done before him. He said that his skills as a pianist never matched hers. In contrast to his work in philosophy, where he challenged the old order, his musical tastes were very traditional – he liked Bach and Beethoven and did not appreciate new classical music such as Arnold Schoenberg’s atonal work.

Karl Popper died, age 92, of cancer on September 17, 1994 in Kenley, England, UK. He was buried beside his wife in Vienna’s Lainzer Friedhof Cemetery. The couple had no children.

Karl Popper“What a monument of human smallness is this idea of the philosopher king. What a contrast between it and the simplicity and humaneness of Socrates, who warned the statesmen against the danger of being dazzled by his own power, excellence, and wisdom, and who tried to teach him what matters most — that we are all frail human beings.”

Karl Popper
The Open Society and Its Enemies, 1945
 
Advertisements

Author of this page: The Doc
Images digitally enhanced and colorized by this website. © All rights reserved.

Cite this Page

Please use the following MLA compliant citation:

"Karl Popper." Famous Scientists. famousscientists.org. 2 Sep. 2016. Web.  
<www.famousscientists.org/karl-popper/>.

Published by FamousScientists.org

Further Reading
Karl Popper
The Logic of Scientific Discovery
Hutchinson of London, 1968

Karl Popper
Conjectures and Refutations: The Growth of Scientific Knowledge
Routledge & Kegan Paul Limited, London, 1963

Karl Popper
Unended Quest, an Intellectual Autobiography
Open Court Publishing Co., Illinois, 1976

Bryan Magee
Popper
Fontana Modern Masters, 1985

More from FamousScientists.org:
  • Paul Dirac
    Paul Dirac
  • Thomas Kuhn
    Thomas Kuhn
  • Francis Bacon
    Francis Bacon
  • Aristotle
    Aristotle
Advertisements

Search Famous Scientists

Scientist of the Week

  • Linda Buck: Discovered how we smell things

Recent Scientists of the Week

  • Jan Ingenhousz: Discovered photosynthesis
  • Barry Marshall: Overturned the Medical Establishment
  • Linus Pauling: Maverick Giant of Chemistry
  • William Röntgen: The Discovery of X-rays
  • Howard Florey: Brought penicillin to the world
  • Henrietta Leavitt: The key to the size of the universe
  • Archimedes: A mind beyond his time
  • Stanley Milgram: The infamous Obedience Experiments
  • C. V. Raman: Color change allows harm-free health check of living cells
  • Rosalind Franklin: Shape-shifting DNA
  • Robert Boyle: A new science is born: chemistry
  • Carl Woese: Rewrote Earth’s history of life
  • Alfred Wegener: Shunned after he discovered that continents move
  • Henri Poincaré: Is the solar system stable?
  • Polly Matzinger: The dog whisperer who rewrote our immune system’s rules
  • Otto Guericke: In the 1600s found that space is a vacuum
  • Alister Hardy: Aquatic ape theory: our species evolved in water
  • Elizebeth Friedman: Became the world’s most famous codebreaker
  • Evangelista Torricelli: We live at the bottom of a tremendously heavy sea of air
  • Eudoxus: The first mathematical model of the universe
  • James Black: Revolutionized drug design with the Beta-blocker
  • Inge Lehmann: Discovered our planet’s solid inner core
  • Chen-Ning Yang: Shattered a fundamental belief of physicists
  • Robert Hooke: Unveiled the spectacular microscopic world
  • Barbara McClintock: A Nobel Prize after years of rejection
  • Pythagoras: The cult of numbers and the need for proof
  • J. J. Thomson: Discovered the electron
  • Johannes Kepler: Solved the mystery of the planets
  • Dmitri Mendeleev: Discovered 8 new chemical elements by thinking
  • Maurice Hilleman: Record breaking inventor of over 40 vaccines
  • Marie Curie: Won – uniquely – both the chemistry & physics Nobel Prizes
  • Jacques Cousteau: Marine pioneer, inventor, Oscar winner
  • Niels Bohr: Founded the bizarre science of quantum mechanics
  • Srinivasa Ramanujan: Untrained genius of mathematics
  • Milutin Milankovic: Proved Earth’s climate is regulated by its orbit
  • Antoine Lavoisier: The giant of chemistry who was executed
  • Emmy Noether: The greatest of female mathematicians, she unlocked a secret of the universe
  • Wilder Penfield: Pioneer of brain surgery; mapped the brain’s functions
  • Charles Nicolle: Eradicated typhus epidemics
  • Samuel Morse: The telegraph and Morse code
  • Jane Goodall: Major discoveries in chimpanzee behavior
  • John Philoponus: 6th century anticipation of Galileo and Newton
  • William Perkin: Youthful curiosity brought the color purple to all
  • Democritus: Atomic theory BC and a universe of diverse inhabited worlds
  • Susumu Tonegawa: Discovered how our bodies make millions of different antibodies
  • Cecilia Payne: Discovered that stars are almost entirely hydrogen and helium

Top 100 Scientists

  • Our Top 100 Scientists

Our Most Popular Scientists

  • Astronomers
  • Biologists & Health Scientists
  • Chemists
  • Geologists and Paleontologists
  • Mathematicians
  • Physicists
  • Scientists in Ancient Times

List of Scientists

  • Alphabetical List

Recent Posts

  • Perfect Numbers and our Tiny Universe
  • What Happens when the Universe chooses its own Units?
  • Hipparchus and the 2000 Year-Old Clue
  • Darwin Pleaded for Cheaper Origin of Species
  • You Will Die For Showing I’m Wrong!
  • Getting Through Hard Times – The Triumph of Stoic Philosophy
  • Johannes Kepler, God, and the Solar System
  • Charles Babbage and the Vengeance of Organ-Grinders
  • Howard Robertson – the Man who Proved Einstein Wrong
  • Susskind, Alice, and Wave-Particle Gullibility




Alphabetical List of Scientists

Louis Agassiz | Maria Gaetana Agnesi | Al-BattaniAbu Nasr Al-Farabi | Alhazen | Jim Al-Khalili | Muhammad ibn Musa al-Khwarizmi | Mihailo Petrovic Alas | Angel Alcala | Salim Ali | Luis Alvarez | Andre Marie Ampère | Anaximander | Carl Anderson | Mary Anning | Virginia Apgar | Archimedes | Agnes Arber | Aristarchus | Aristotle | Svante Arrhenius | Oswald Avery | Amedeo Avogadro | Avicenna

Charles Babbage | Francis Bacon | Alexander Bain | John Logie Baird | Joseph Banks | Ramon Barba | John Bardeen | Charles Barkla | Ibn Battuta | William Bayliss | George Beadle | Arnold Orville Beckman | Henri Becquerel | Emil Adolf Behring | Alexander Graham Bell | Emile Berliner | Claude Bernard | Timothy John Berners-Lee | Daniel Bernoulli | Jacob Berzelius | Henry Bessemer | Hans Bethe | Homi Jehangir Bhabha | Alfred Binet | Clarence Birdseye | Kristian Birkeland | James Black | Elizabeth Blackwell | Alfred Blalock | Katharine Burr Blodgett | Franz Boas | David Bohm | Aage Bohr | Niels Bohr | Ludwig Boltzmann | Max Born | Carl Bosch | Robert Bosch | Jagadish Chandra Bose | Satyendra Nath Bose | Walther Wilhelm Georg Bothe | Robert Boyle | Lawrence Bragg | Tycho Brahe | Brahmagupta | Hennig Brand | Georg Brandt | Wernher Von Braun | J Harlen Bretz | Louis de Broglie | Alexander Brongniart | Robert Brown | Michael E. Brown | Lester R. Brown | Eduard Buchner | Linda Buck | William Buckland | Georges-Louis Leclerc, Comte de Buffon | Robert Bunsen | Luther Burbank | Jocelyn Bell Burnell | Macfarlane Burnet | Thomas Burnet

Benjamin Cabrera | Santiago Ramon y Cajal | Rachel Carson | George Washington Carver | Henry Cavendish | Anders Celsius | James Chadwick | Subrahmanyan Chandrasekhar | Erwin Chargaff | Noam Chomsky | Steven Chu | Leland Clark | John Cockcroft | Arthur Compton | Nicolaus Copernicus | Gerty Theresa Cori | Charles-Augustin de Coulomb | Jacques Cousteau | Brian Cox | Francis Crick | James Croll | Nicholas Culpeper | Marie Curie | Pierre Curie | Georges Cuvier | Adalbert Czerny

Gottlieb Daimler | John Dalton | James Dwight Dana | Charles Darwin | Humphry Davy | Peter Debye | Max Delbruck | Jean Andre Deluc | Democritus | René Descartes | Rudolf Christian Karl Diesel | Diophantus | Paul Dirac | Prokop Divis | Theodosius Dobzhansky | Frank Drake | K. Eric Drexler

John Eccles | Arthur Eddington | Thomas Edison | Paul Ehrlich | Albert Einstein | Gertrude Elion | Empedocles | Eratosthenes | Euclid | Eudoxus | Leonhard Euler

Michael Faraday | Pierre de Fermat | Enrico Fermi | Richard Feynman | Fibonacci – Leonardo of Pisa | Emil Fischer | Ronald Fisher | Alexander Fleming | John Ambrose Fleming | Howard Florey | Henry Ford | Lee De Forest | Dian Fossey | Leon Foucault | Benjamin Franklin | Rosalind Franklin | Sigmund Freud | Elizebeth Smith Friedman

Galen | Galileo Galilei | Francis Galton | Luigi Galvani | George Gamow | Martin Gardner | Carl Friedrich Gauss | Murray Gell-Mann | Sophie Germain | Willard Gibbs | William Gilbert | Sheldon Lee Glashow | Robert Goddard | Maria Goeppert-Mayer | Thomas Gold | Jane Goodall | Stephen Jay Gould | Otto von Guericke

Fritz Haber | Ernst Haeckel | Otto Hahn | Albrecht von Haller | Edmund Halley | Alister Hardy | Thomas Harriot | William Harvey | Stephen Hawking | Otto Haxel | Werner Heisenberg | Hermann von Helmholtz | Jan Baptist von Helmont | Joseph Henry | Caroline Herschel | John Herschel | William Herschel | Gustav Ludwig Hertz | Heinrich Hertz | Karl F. Herzfeld | George de Hevesy | Antony Hewish | David Hilbert | Maurice Hilleman | Hipparchus | Hippocrates | Shintaro Hirase | Dorothy Hodgkin | Robert Hooke | Frederick Gowland Hopkins | William Hopkins | Grace Murray Hopper | Frank Hornby | Jack Horner | Bernardo Houssay | Fred Hoyle | Edwin Hubble | Alexander von Humboldt | Zora Neale Hurston | James Hutton | Christiaan Huygens | Hypatia

Ernesto Illy | Jan Ingenhousz | Ernst Ising | Keisuke Ito

Mae Carol Jemison | Edward Jenner | J. Hans D. Jensen | Irene Joliot-Curie | James Prescott Joule | Percy Lavon Julian

Michio Kaku | Heike Kamerlingh Onnes | Pyotr Kapitsa | Friedrich August Kekulé | Frances Kelsey | Pearl Kendrick | Johannes Kepler | Abdul Qadeer Khan | Omar Khayyam | Alfred Kinsey | Gustav Kirchoff | Martin Klaproth | Robert Koch | Emil Kraepelin | Thomas Kuhn | Stephanie Kwolek

Joseph-Louis Lagrange | Jean-Baptiste Lamarck | Hedy Lamarr | Edwin Herbert Land | Karl Landsteiner | Pierre-Simon Laplace | Max von Laue | Antoine Lavoisier | Ernest Lawrence | Henrietta Leavitt | Antonie van Leeuwenhoek | Inge Lehmann | Gottfried Leibniz | Georges Lemaître | Leonardo da Vinci | Niccolo Leoniceno | Aldo Leopold | Rita Levi-Montalcini | Claude Levi-Strauss | Willard Frank Libby | Justus von Liebig | Carolus Linnaeus | Joseph Lister | John Locke | Hendrik Antoon Lorentz | Konrad Lorenz | Ada Lovelace | Percival Lowell | Lucretius | Charles Lyell | Trofim Lysenko

Ernst Mach | Marcello Malpighi | Jane Marcet | Guglielmo Marconi | Lynn Margulis | Barry Marshall | Polly Matzinger | Matthew Maury | James Clerk Maxwell | Ernst Mayr | Barbara McClintock | Lise Meitner | Gregor Mendel | Dmitri Mendeleev | Franz Mesmer | Antonio Meucci | John Michell | Albert Abraham Michelson | Thomas Midgeley Jr. | Milutin Milankovic | Maria Mitchell | Mario Molina | Thomas Hunt Morgan | Samuel Morse | Henry Moseley

Ukichiro Nakaya | John Napier | Giulio Natta | John Needham | John von Neumann | Thomas Newcomen | Isaac Newton | Charles Nicolle | Florence Nightingale | Tim Noakes | Alfred Nobel | Emmy Noether | Christiane Nusslein-Volhard | Bill Nye

Hans Christian Oersted | Georg Ohm | J. Robert Oppenheimer | Wilhelm Ostwald | William Oughtred

Blaise Pascal | Louis Pasteur | Wolfgang Ernst Pauli | Linus Pauling | Randy Pausch | Ivan Pavlov | Cecilia Payne-Gaposchkin | Wilder Penfield | Marguerite Perey | William Perkin | John Philoponus | Jean Piaget | Philippe Pinel | Max Planck | Pliny the Elder | Henri Poincaré | Karl Popper | Beatrix Potter | Joseph Priestley | Proclus | Claudius Ptolemy | Pythagoras

Adolphe Quetelet | Harriet Quimby | Thabit ibn Qurra

C. V. Raman | Srinivasa Ramanujan | William Ramsay | John Ray | Prafulla Chandra Ray | Francesco Redi | Sally Ride | Bernhard Riemann | Wilhelm Röntgen | Hermann Rorschach | Ronald Ross | Ibn Rushd | Ernest Rutherford

Carl Sagan | Abdus Salam | Jonas Salk | Frederick Sanger | Alberto Santos-Dumont | Walter Schottky | Erwin Schrödinger | Theodor Schwann | Glenn Seaborg | Hans Selye | Charles Sherrington | Gene Shoemaker | Ernst Werner von Siemens | George Gaylord Simpson | B. F. Skinner | William Smith | Frederick Soddy | Mary Somerville | Arnold Sommerfeld | Hermann Staudinger | Nicolas Steno | Nettie Stevens | William John Swainson | Leo Szilard

Niccolo Tartaglia | Edward Teller | Nikola Tesla | Thales of Miletus | Theon of Alexandria | Benjamin Thompson | J. J. Thomson | William Thomson | Henry David Thoreau | Kip S. Thorne | Clyde Tombaugh | Susumu Tonegawa | Evangelista Torricelli | Charles Townes | Youyou Tu | Alan Turing | Neil deGrasse Tyson

Harold Urey

Craig Venter | Vladimir Vernadsky | Andreas Vesalius | Rudolf Virchow | Artturi Virtanen | Alessandro Volta

Selman Waksman | George Wald | Alfred Russel Wallace | John Wallis | Ernest Walton | James Watson | James Watt | Alfred Wegener | John Archibald Wheeler | Maurice Wilkins | Thomas Willis | E. O. Wilson | Sven Wingqvist | Sergei Winogradsky | Carl Woese | Friedrich Wöhler | Wilbur and Orville Wright | Wilhelm Wundt

Chen-Ning Yang

Ahmed Zewail

Return to top of page

Famous Scientists - Privacy - Contact - About - Content & Imagery © 2023