Pivotal Paradigm Shifts

The Structure Of Scientific Revolutions: Thomas Kuhn's 1962 book argued that science advances not by steady accumulation but by upheavals in which a ruling framework collapses and is replaced, a vision that made paradigm shift a household phrase.

De Revolutionibus: Copernicus's 1543 book placed the Sun at the center of the universe, and legend says he received a printed copy on his deathbed, never seeing the storm it would unleash.

Charles Darwin: The first edition of On the Origin of Species in 1859 sold out to booksellers on the first day, and its idea of natural selection removed purpose from the explanation of life.

Ignaz Semmelweis: In 1847 he showed that doctors washing their hands with chlorinated lime cut deaths from childbed fever in a Vienna clinic dramatically, yet most of his peers rejected the idea.

John Snow: His 1854 map of cholera deaths around London's Broad Street pump pointed to contaminated water rather than foul air, helping topple the miasma theory of disease.

Louis Pasteur: His swan necked flask experiments of the early 1860s showed that broth stayed clear when airborne microbes were blocked, ending the belief in spontaneous generation.

Robert Koch: His 1882 identification of the bacterium that causes tuberculosis and his rules for linking germs to diseases cemented germ theory as the new paradigm in medicine.

James Hutton: Studying rock layers at Siccar Point in Scotland, he concluded in 1788 that Earth's processes work slowly over unimaginable ages, opening up the idea of deep time.

Lord Kelvin: He argued that Earth could be only tens of millions of years old based on its cooling, a calculation that clashed with geology and fell apart once radioactivity revealed a hidden source of heat.

Clair Patterson: In 1956 he dated meteorite lead and fixed Earth's age at about 4.55 billion years, then went on to campaign against leaded gasoline after finding lead contamination everywhere.

Michelson Morley Experiment: This 1887 test failed to detect the luminiferous ether, and it is often called the most famous failed experiment in science, setting the stage for relativity.

Annus Mirabilis Papers: In 1905, while working as a patent clerk, Albert Einstein published four papers, including special relativity, that overturned the idea of absolute time and space.

Eddington Eclipse Expedition: In 1919 Arthur Eddington's teams measured starlight bending around the Sun during an eclipse, confirming Einstein's general relativity and making him world famous.

Planck's Quantum Hypothesis: In 1900 Max Planck proposed that energy comes in discrete packets, a move he later described as an act of desperation that nonetheless launched quantum physics.

Kurt Godel: His 1931 incompleteness theorems proved that any consistent formal system rich enough for arithmetic contains true statements it cannot prove, shattering the hope for complete mathematical certainty.

Alfred Wegener: His 1912 theory of continental drift was mocked for lacking a mechanism, but ocean floor discoveries in the 1960s vindicated him as plate tectonics became the new foundation of geology.

Edwin Hubble: Using a variable star in the Andromeda nebula in the mid 1920s, he showed that it lies far outside the Milky Way, proving that our galaxy is just one of many.

Penzias And Wilson: Two Bell Labs engineers in 1964 chased a persistent hiss in their antenna, even cleaning out pigeon droppings, and found the cosmic background radiation that tipped cosmology toward the Big Bang.

Antoine Lavoisier: In the 1770s and 1780s he used careful measurement to replace the phlogiston theory of fire with oxygen chemistry and the conservation of mass.

Friedrich Wohler: His 1828 synthesis of urea from inorganic ingredients is often told as the death of vitalism, though historians note the shift away from a special life force was more gradual.

Barry Marshall: In 1984 he drank a culture of Helicobacter pylori to prove that bacteria cause stomach ulcers, overturning the belief that stress and acid were to blame and earning a Nobel Prize.

Prospect Theory: Daniel Kahneman and Amos Tversky's 1979 paper showed that people feel losses more sharply than equal gains, undermining the model of the fully rational economic actor.

Bounded Rationality: Herbert Simon's idea that people satisfice, choosing options that are good enough because of limited time and information, was an early crack in classical economics.

Chomsky Review Of Skinner: Noam Chomsky's 1959 critique of B. F. Skinner's Verbal Behavior argued that learning language cannot be explained by reward and punishment alone, helping bring down strict behaviorism.

MIT Symposium On Information Theory: At a September 1956 meeting, researchers presented work by Newell and Simon, Chomsky and Miller, an event often used as a birthday of the cognitive revolution.