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The following is a list of historically important scientificexperiments and observations demonstrating something of great scientific interest, typically in an elegant or clever manner.

• Ole Rømer makes the first quantitative estimate of thespeed of light in 1676 by timing the motions of Jupiter's satelliteIo with a telescope
• Arno Penzias andRobert Wilson detect thecosmic microwave background radiation, giving support to the theory of theBig Bang (1964)
• Kerim Kerimov launchesKosmos 186 and Kosmos 188 as experiments on automatic docking eventually leading to the development ofspace stations (1967)
• TheSupernova Cosmology Project and theHigh-Z Supernova Search Team discover, by observingType Ia supernovae, that theexpansion of the Universe is accelerating (1998)
• Galileo Galilei uses atelescope to observe that themoons of Jupiter appear to circleJupiter. This evidence supports theheliocentric model, and weakens thegeocentric model of the cosmos (1609)

• Robert Hooke, using amicroscope, observescells (1665).
• Anton van Leeuwenhoek discoversmicroorganisms (1674–1676).
• James Lind, publishes 'A Treatise of the Scurvy' which describes a controlled shipboard experiment using two identical populations but with only one variable, the consumption of citrus fruit (1753).
• Edward Jenner tests his hypothesis for the protective action of mild cowpox infection forsmallpox, the firstvaccine (1796).
• Gregor Mendel's experiments with the gardenpea led him to surmise many of the fundamental laws of genetics (dominant vsrecessive genes, the 1–2–1 ratio, seeMendelian inheritance) (1856–1863).
• Charles Darwin demonstratesevolution bynatural selection using many examples (1859).
• Louis Pasteur uses S-shaped flasks to preventspores from contaminating broth. This disproves the theory ofSpontaneous generation (1861) extending the rancid meat experiment ofFrancesco Redi (1668) to the micro scale.
• Charles Darwin and his sonFrancis, using dark-grown oat seedlings, discover the stimulus forphototropism is detected at the tip of the shoot (thecoleoptile tip), but the bending takes place in the region below the tip (1880).
• Emil von Behring andKitasato Shibasaburō demonstratepassive immunity, protection of animals from infection by injection ofimmune serum (1890).
• Thomas Hunt Morgan identifies asex chromosome linkedgene inDrosophila melanogaster (1910) and his studentAlfred Sturtevant develops the first genetic map (1913).
• Alexander Fleming demonstrates that the zone of inhibition around a growth ofpenicillin mould on a culture dish of bacteria is caused by a diffusible substance secreted by the mould (1928).
• Frederick Griffith demonstrates (Griffith's experiment) that living cells can be transformed via atransforming principle, later discovered to beDNA (1928).
• Karl von Frisch decodes thewaggle dancehoney bees use to communicate the location of flowers (1940).
• George Wells Beadle andEdward Lawrie Tatum moot the "one gene-one enzyme hypothesis" based on induced mutations in bread moldNeurospora crassa (1941).
• Luria–Delbrück experiment demonstrates that in bacteria, beneficial mutations arise in the absence of selection, rather than being a response to selection (1943).
• Barbara McClintock breedsmaize plants for color, which leads to the discovery of transposable elements orjumping genes (1944).
• Linus Pauling and colleagues show in "Sickle Cell Anemia, a Molecular Disease" that a human genetic disease,sickle cell anemia, is caused by a molecular change in a specific protein,hemoglobin (1949).
• Hershey–Chase experiment (byAlfred Hershey andMartha Chase) usesbacteriophage to prove thatDNA is the hereditary material (1952).
• Meselson–Stahl experiment proves thatDNA replication issemiconservative (1958).
• Crick, Brenner et al. experiment using frameshift mutations to support the triplet nature of the genetic code (1961).
• Nirenberg and Matthaei experiment demonstratingin vitroprotein synthesis using synthetic RNA as to substitute formessenger RNA (1961).
• John Gurdonclones an animal, afrog tadpole, from anegg cell using the nucleus from anintestinal cell (1962).
• Roger W. Sperry shows the potential independence of the two sides of the human brain usingsplit-brain patients (1962–1965).
• Nirenberg and Leder experiment, bindingtRNA to ribosomes with synthetic RNA to decipher the genetic code (1964).
• Demonstration of the role ofreverse transcriptases in tumorviruses, independently byHoward Temin andDavid Baltimore, 1970.
• Herbert Boyer andStanley Cohen selectively clone genes in bacteria, using bacterial plasmids cut by specific endonucleases (1975).
• Mary-Dell Chilton shows that crown gall tumors of plants are caused by the transfer of a small piece of DNA from the bacteriumAgrobacterium tumefaciens into the host plant, where it becomes part of its genome (1977).
• Napoli, Lemieux and Jorgensen discover the principle ofRNA interference (1990).

• Robert Boyle uses anair pump to determine the inverse relationship between thepressure andvolume of agas. This relationship came to be known asBoyle's law (1660–1662).
• Joseph Priestley suspends a bowl of water above a beer vat at a brewery and synthesizescarbonated water (1767).
• Antoine Lavoisier determines thatoxygen combines with materials uponcombustion, thus disprovingphlogiston theory (1783).
• Antoine Lavoisier determines thatchemical reactions in a closed container do not alter total mass. From these observations he establishes the law ofconservation of mass (1789).
• Benjamin Thompson, Count Rumford demonstrates that theheat developed by the friction of boring cannon is nearly inexhaustible. This result was presented in opposition tocaloric theory (1798).
• Humphry Davy useselectrolysis to isolate elementalpotassium,sodium,calcium,strontium,barium,magnesium, andchlorine (1807–1810).
• Joseph Louis Gay-Lussac studies reactions among gases and determines that their volumes combine chemically in simple integer ratios (1809).
• Robert Brown studies very small particles in water under the microscope and observesBrownian motion which was later named in his honor (1827).
• Friedrich Wöhlersynthesizes theorganic compoundurea usinginorganic reactants, disproving the application ofvitalism to chemical processes (1828).
• Thomas Graham measures the rates ofeffusion for different gases and establishesGraham's law of effusion anddiffusion (1833).
• Julius Robert von Mayer andJames Prescott Joule measure theheat generated by mechanical work. This establishes the principle ofconservation of energy and thekinetic theory of heat (1842–1843).
• Louis Pasteur separates aracemic mixture of twoenantiomers by sorting individualcrystals, and demonstrates their impact on thepolarization of light (1849).
• Anders Jonas Ångström observes the presence ofhydrogen and other elements in thespectrum of the sun (1862).
• François-Marie Raoult demonstrates that the decrease in thevapor pressure andfreezing point of liquids caused by the addition of solutes is proportional to the number of solute molecules present. This establishes the concept ofcolligative properties (1878).
• Svante Arrhenius studies theconductivity ofsalt solutions and determines that saltsdissociate intoions in water (1884).
• Svante Arrhenius determines the impact of temperature onreaction rates and formulates the concept ofactivation energy (1889).
• William Ramsay andLord Rayleigh (John Strutt) isolate thenoble gases (1894–1898).
• Henri Becquerel,Marie Curie, andPierre Curie discoverradioactivity and describe its properties (1896).
• Mikhail Tsvet (Mikhail Semyonovich Tsvet) separateschlorophyll from other plant pigments usingchromatography (1901).
• Frederick Soddy andWilliam Ramsay observe the production ofhelium fromalpha particles duringradioactive decay (1903).
• Ernest Rutherford discovers that atoms have a very small positively charged nucleus in the gold-foil experiment, also known as theGeiger–Marsden experiment (1909).
• Otto Hahn discoversnuclear isomerism (1921).
• Albert Szent-Györgyi andHans Adolf Krebs discover thecitric acid cycle ofoxidative metabolism (1935-1937).
• Otto Hahn andFritz Strassmann discover thenuclear fission of uranium (1938).
• Glenn Theodore Seaborg and colleagues create and isolate fivetransuranium elements. They reorganize theperiodic table to its current form. (1941–1950).
• Miller–Urey experiment demonstrates thatorganic compounds can arise spontaneously frominorganic ones (1953).
• Melvin Calvin andAndrew Benson delineate the path of carbon inphotosynthesis usingChlorella andcarbon dioxide labeled withcarbon-14 (¹⁴CO₂) (1945–1954).
• Erwin Chargaff disproves the "tetranucleoide theory" ofDNA structure and determines that the composition of double-stranded DNA follows the rule, %A = %T and %G = %C (Chargaff's rule). This discovery was critical to the formulation of the Watson-Crick Model of DNA structure.
• Neil Bartlett mixesxenon andplatinum hexafluoride leading to the first synthesis of anoble gas compound,xenon hexafluoroplatinate (1962).
• Robert Burns Woodward announces the total synthesis ofVitamin B-12 by a team he led (1973). Insights from this work lead him andRoald Hoffmann to formulate theWoodward–Hoffmann rules for elucidating thestereochemistry of the products of organic reactions.
• Frederick Sanger demonstrates the dideoxy- orchain termination method for determining DNA sequences (1975).
• Kary Mullis demonstrates thepolymerase chain reaction, a method for amplifying specific bits of DNA (1983).

• The experiments ofMuhammad Yunus on the applications ofmicrocredit andmicrofinance in ruralBangladesh (1971)
• Robert Axelrod'sprisoner's dilemma computer tournaments, later documented inThe Evolution of Cooperation (1984)

• Charles Mason conducts an experiment near the Scottish mountain ofSchiehallion that attempts to measure the mean density of the Earth for the first time. Known as theSchiehallion experiment (1774)

• Inclined plane experiment (1602–07):Galileo Galilei uses rolling balls to disprove theAristotelian theory of motion.
• Atmospheric pressure vs. altitude experiment (1648):Blaise Pascal carries abarometer up a church tower and a mountain to determine that atmospheric pressure is due to a column of air.
• Magdeburg hemispheres (1654):Otto von Guericke demonstrates atmospheric pressure using a pair of hollow copper hemisphere.
• Spring of air experiment (1660):Robert Boyle shows that the volume of a given amount of gas is inversely related to the pressure upon it.
• Kite experiment (1700s):Benjamin Franklin beginning in 1747 describes experiments in letters toPeter Collinson demonstrating electrical principles which were published in a book calledExperiments and Observations on Electricity.
• Voltaic pile (1796):Alessandro Volta constructs a new source of electricity, theelectrical battery.
• Cavendish experiment (1798):Henry Cavendish's torsion bar experiment measures the force of gravity in a laboratory.
• Double-slit experiment (c.1805):Thomas Young shows that light is a wave in his double-slit experiment.
• Arago spot (1819): Observation of circular diffraction byFrançois Arago, validated a newwave theory of light byAugustin-Jean Fresnel disproving skeptics likeSiméon Denis Poisson.
• Ørsted experiment (1820):Hans Christian Ørsted demonstrates the connection ofelectricity andmagnetism by experiments involving acompass andelectric circuits.
• Discovery of electromagnetic induction (1831):Michael Faraday discoversmagnetic induction in an experiment with a closed ring of soft iron, with two windings of wire.
• Joule's experiment (1834):James Prescott Joule demonstrates themechanical equivalent of heat, an important step in the development ofthermodynamics.
• Doppler experiment (1845):Christian Doppler arranges to have trumpets played from a passingtrain. The ground-observed pitch was higher than that played when the train was approaching then lower than that played as the train passed and moved away, demonstrating theDoppler effect.
• Foucault pendulum (1851):Léon Foucault's creates a pendulum to demonstrate theCoriolis effect and the rotation of the Earth.
• Michelson–Morley experiment (1887): exposes weaknesses of the prevailing variant of the theory ofluminiferous aether.
• Hertz wireless experiments (1887):Heinrich Hertz demonstratesfree spaceelectromagnetic waves, predicted byMaxwell's equations, with a simpledipole antenna and spark gaposcillator.
• Thomson's experiments withcathode rays (1897):J. J. Thomson's cathode ray tube experiments (discovers theelectron and its negative charge).
• Eötvös experiment (1909):Loránd Eötvös publishes the result of the second series of experiments, clearly demonstrating that inertial and gravitational mass are one and the same.
• Oil-drop experiment (1909):Robert Millikan demonstrates thatelectric charge occurs asquanta (whole units).
• Geiger–Marsden experiments (1911):Ernest Rutherford's gold foil experiment demonstrated that the positive charge and mass of an atom is concentrated in a small, centralatomic nucleus, disproving the then-popularplum pudding model of theatom.

• Eddington experiment (1919):Arthur Eddington leads an expedition to the island ofPrincipe to observe a total solar eclipse (gravitational lensing). This allows for an observation of the bending of starlight under gravity, a prediction ofAlbert Einstein'stheory of relativity. It was confirmed (although it was later shown that the margin of error was as great as the observed bending).
• Stern–Gerlach experiment (1920):Otto Stern andWalther Gerlach demonstrates particlespin.
• Chicago Pile-1 (1942):Enrico Fermi andLeó Szilárd build the first critical nuclear reactor (1942)
• Wu experiment (1956):Chien-Shiung Wu leads the team that disproves the conservation ofparity in particle physics.
• Cowan–Reines neutrino experiment (1955):Clyde L. Cowan andFrederick Reines confirm the existence of theneutrino.
• Hafele-Keating experiment (1971):Joseph C. Hafele andRichard E. Keating show thatatomic clocks flown around the world exhibit differences which are consistent with the predictions of special and general relativity.
• Scout rocket experiment (1976): confirms thetime dilation effect ofgravity.
• Aspect's experimentLAlain Aspect demonstrates the violation ofBell inequalities inquantum entanglement in the 1980s.

• Ivan Pavlov's experiments with dogs andclassical conditioning (1900s)
• John B. Watson andRosalie Rayner conduct theLittle Albert experiment showing evidence ofclassical conditioning (1920)
• TheAsch conformity experiments shows how group pressure can persuade an individual to conform to an obviously wrong opinion (1951)
• B. F. Skinner's demonstrations ofoperant conditioning (1930s–1960s)
• Harry Harlow's experiments with baby monkeys and wire and cloth surrogate mothers (1957–1974)
• Stanley Milgram'sexperiments on human obedience (1963)
• Walter Mischel'smarshmallow experiment showing the importance to life outcomes of the ability to delay gratification (beginning late 1960s)
• Philip Zimbardo'sStanford prison experiment (1971)
• Allan andBeatrix Gardner's attempts to teachAmerican Sign Language to thechimpanzeeWashoe (1970s)
• Martin Seligman studieslearned helplessness in dogs (1970s)
• Rosenhan experiment (1972). It involved the use of healthy associates or "pseudopatients", who briefly simulated auditory hallucinations in an attempt to gain admission to 12 different psychiatric hospitals. The hospital staff failed to detect a single pseudopatient. The study is considered an important and influential criticism of psychiatric diagnosis.
• Kansas City preventive patrol experiment (1972–1973) It was designed to test the assumption that the presence (or potential presence) of police officers in marked cars reduced the likelihood of a crime being committed. No relationship was found.
• Elizabeth Loftus' andJohn C. Palmer's car crash experiment shows thatleading questions can producefalse memories (1974)
• Benjamin Libet's experiment on free will shows that a readiness potential appears before the notion of doing the task enters conscious experience, sparking debate about the illusory nature of free will yet again. (1983)
• Vilayanur S. Ramachandran's experiment on phantom limbs with the Mirror Box throw light on the nature of 'learned paralysis' (1998)

• List of thought experiments
• Timeline of scientific experiments

• Experiments
• Science-related lists
• History of science
• Science experiments

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