Timeline

Only events with a documented date (publication, experiment, observation) are placed on the timeline. Items whose dates are disputed are listed separately at the bottom.

Before the Common Era

c. 2560 BCE
The Great Pyramid (Pyramid of Khufu) · Art, music and aesthetics
The Great Pyramid at Giza was built in the 26th century BCE for the pharaoh Khufu of Egypt's 4th Dynasty. At about 146 metres it remained the tallest known human structure for some 3,800 years. A logbook kept by an official named Merer, found on the Red Sea coast, tells how limestone blocks were shipped by boat to Giza. How the blocks were raised onto the pyramid is not known for certain, and different ramp models have been proposed.
c. 1800 BCE
Babylonian mathematics and Plimpton 322 · Mathematics
The Babylonians used a base-60 number system. Our 60-minute hour and 360-degree circle come from it. The clay tablet known as Plimpton 322 lists numbers we now call "Pythagorean triples". What the tablet was written for is debated.
c. 1754 BCE
The Laws of Hammurabi · Law and politics
Around 280 provisions carved on a stone stele under the Babylonian king Hammurabi form one of the most extensive early written legal texts known. They regulate "an eye for an eye", trade, family and punishments, which vary with a person's social class. Whether the text was a code actually applied in daily life or a display of the king's justice is debated.
c. 1200 BCE
The Epic of Gilgamesh · Mythology
This Mesopotamian epic, telling of Gilgamesh, king of Uruk, seeking immortality after the death of his friend Enkidu, is among the oldest known works of literature. Tablet XI contains the flood story of Utnapishtim, who, warned by a god, builds a boat and saves living creatures. The story has been compared with the Noah narratives in Genesis and the Qur'an.
c. 585 BCE
The Presocratics and ancient atomism · Philosophy
Thales of Miletus and his successors tried to explain nature through a principle (archē) that is the source of all things rather than through myth: water for Thales, the boundless for Anaximander. Democritus and Leucippus proposed that everything consists of indivisible "atoms" moving in the void. This was reasoning not based on experiment; modern atomic theory has experimental origins.
c. 375 BCE
Plato, the Republic and the theory of Forms · Philosophy
Plato argued that behind the changing world we perceive with the senses there are unchanging "Forms". He held that true knowledge is directed at these Forms, such as the Good and Justice themselves. In the Republic he used the allegory of the cave to describe people who take shadows for reality, and discussed how a just society could be built.
c. 350 BCE
Pāṇini's grammar of Sanskrit · Linguistics
The Indian grammarian Pāṇini described the entire grammar of Sanskrit in about 4,000 short rules in his Aṣṭādhyāyī. The rules form a system of cross-references that works almost like a computer program. It has had a direct influence on modern linguistics and formal language theory.
c. 350 BCE
Aristotle and logic · Philosophy
Aristotle was the first philosopher to study systematically the rules of valid reasoning; his theory of the syllogism was the basis of logic for about two thousand years. His writings on physics, biology, ethics and politics earned him the title "al-Muʿallim al-Awwal" (the First Teacher) in the Islamic world. Some of his views on physics, such as heavier bodies falling faster, were later challenged by experiment.
c. 300 BCE
Stoicism · Philosophy
Stoicism is a school of philosophy founded in Athens around 300 BCE by Zeno of Citium. For the Stoics virtue is the only true good, and happiness is living in agreement with nature and reason. One should distinguish what is up to us from what is not, and not be troubled by the latter. The writings of Seneca, Epictetus and Marcus Aurelius still reach a wide readership.
c. 300 BCE
Euclid's Elements · Mathematics
Euclid built geometry from a few basic assumptions (axioms and postulates), proving everything step by step. This "axiomatic method" served as the model for mathematics for more than two thousand years. The realisation that the fifth (parallel) postulate cannot be derived from the others gave rise to non-Euclidean geometries.

1–1500

c. 150
Ptolemy's Almagest and the geocentric model · Astronomy and cosmology
Ptolemy's Almagest was a model placing the Earth at the centre and explaining planetary motion with nested circles (epicycles). For about 1,400 years it predicted planetary positions with usable accuracy. The work was translated into Arabic, and astronomers in the Islamic world, especially at the Maragha and Samarkand observatories, criticised and improved it.
December 537
Hagia Sophia · Art, music and aesthetics
Hagia Sophia was designed by Anthemius of Tralles and Isidore of Miletus on the orders of the Byzantine emperor Justinian I and opened in 537. Its dome, about 31 metres across, was set on four pendentives and buttressed by semi-domes over a vast interior. The first dome collapsed after an earthquake in 558 and was rebuilt higher in 562. The building became a mosque in 1453, a museum in 1934 and a mosque again in 2020.
610
Islam and the Qur'an · Religions and scriptures
In Islamic belief the Qur'an is the word of God revealed to the Prophet Muhammad over about 23 years from 610 onward. Islam's basic articles of faith are God's oneness (tawḥīd), prophethood, the scriptures, angels, the hereafter and divine decree. The Qur'an calls people to reason, to reflect and to look at the "signs" (āyāt) in the universe. There are about 2 billion Muslims in the world.
628
Zero as a number · Mathematics
Writing down rules for zero, not merely as an "empty place" marker but as a number used in calculation, happened in India. In 628 Brahmagupta gave rules for adding, subtracting and multiplying with zero. Whether an older zero appears in the Bakhshali manuscript is debated.
712
Shinto and the Kojiki · Religions and scriptures
Shinto is a Japanese tradition based on reverence for sacred beings (kami) present in nature, ancestors and places. Shrines (jinja), purification rituals and seasonal festivals are central. The Kojiki, compiled in 712, tells how the Japanese islands and the imperial line descend from the gods. How long Shinto has existed as a separate religion is debated: for centuries it was practised intertwined with Buddhism, and it was separated from it by the state after 1868.
732
The Orkhon inscriptions · Linguistics
The Kül Tigin (732) and Bilge Khagan (735) memorial stones erected in the Orkhon Valley in Mongolia are among the oldest datable long texts in the Turkic language. Written in the Old Turkic script, they contain counsel on state, people and rule in Bilge Khagan's voice. The script was deciphered in 1893 by the Danish linguist Vilhelm Thomsen.
c. 750
The Muʿtazila · Kalām (Islamic theology)
The Muʿtazila is the kalām school that gave priority to reason and human will in interpreting matters of belief. It emphasised God's justice, held that humans create their own acts by their own will, and maintained that the Qur'an is created. For a time under the Abbasids it became the official view (the Miḥna, 833–848).
c. 800
Jābir ibn Ḥayyān and the Jābirian corpus · Esoteric traditions
The most famous name in Islamic alchemy is Jābir ibn Ḥayyān. Hundreds of works bearing his name deal with the classification of substances, distillation and the mercury–sulphur theory; their Latin translations ("Geber") deeply influenced European alchemy. Whether these works belong to a single person or form a corpus built up over time is debated.
c. 820
Fiqh and uṣūl al-fiqh (Islamic law) · Law and politics
Fiqh is the Islamic discipline studying the practical rulings of religion, from worship and trade to family law and penalties. Uṣūl al-fiqh studies the methods by which rulings are derived from sources such as the Qur'an, the Sunna, consensus (ijmāʿ) and analogy (qiyās). The earliest surviving work of uṣūl is al-Shāfiʿī's al-Risāla. The Ḥanafī, Mālikī, Shāfiʿī and Ḥanbalī schools are the main Sunni legal schools.
c. 820
Al-Khwārizmī and algebra · Mathematics
Al-Khwārizmī, working at the House of Wisdom in Baghdad, gave the word "algebra" its name with his book on solving equations systematically. The word "algorithm" also comes from the Latin form of his name. Historians debate whether the "father" of algebra is al-Khwārizmī or the earlier Diophantus of Alexandria.
c. 900
Māturīdism · Kalām (Islamic theology)
Māturīdism, formed around the views of al-Māturīdī of Samarkand, is a Sunni kalām school that aims to balance transmitted texts and reason. It grants human will more room than Ashʿarism and holds that God's existence and basic good and evil can be known by reason. It is widespread in the Turkic world, Central Asia and among Ḥanafīs.
910
al-Junayd al-Baghdādī and "sober" Sufism · Sufism (taṣawwuf)
Al-Junayd of Baghdad (d. 910) is one of the most influential figures of early Sufism. He defined Sufism as a path bound to the Qur'an and the Sunna and in harmony with the sharia. Instead of sayings uttered in ecstasy (sukr) he emphasised sobriety (ṣaḥw). Many later orders trace their chains of transmission to him, and he is called "master of the group" (sayyid al-ṭāʾifa).
c. 912
Ashʿarism and occasionalism · Kalām (Islamic theology)
Al-Ashʿarī broke with the Muʿtazila and founded a school that sought to reconcile transmitted texts and reason. For the Ashʿarīs the only true agent in the world is God: fire burning cotton is a "custom" (ʿāda) that God creates anew at every moment, not a necessary result of fire's own nature. This view is known in Western philosophy as occasionalism, and has resurfaced in current debates about evolution and science.
March 922
al-Ḥallāj and "Anā al-Ḥaqq" · Sufism (taṣawwuf)
Al-Ḥallāj is a Sufi known for the words "Anā al-Ḥaqq" ("I am the Truth", al-Ḥaqq being one of the names of God). After a long trial he was executed in Baghdad in 922. What his words meant and why he was punished have been debated for centuries. Some saw him as having strayed from the religion, while many Sufis read his words as an expression of the servant passing away in God's being (fanāʾ). Historians also stress the political side of the trial.
c. 1021
Ibn al-Haytham and the Book of Optics · Physics
Born in Basra, Ibn al-Haytham argued in his Kitāb al-Manāẓir (Book of Optics) that vision occurs not by rays leaving the eye but by light coming from objects to the eye. He studied the rectilinear propagation of light, reflection, refraction and the camera obscura by experiment, which is why some historians count him among the pioneers of the experimental method. Translated into Latin, the work influenced European optics up to Kepler.
c. 1025
Ibn Sīnā's Canon of Medicine · Medicine
Ibn Sīnā's five-volume medical encyclopedia, the Canon, brought Greek, Indian and Islamic medicine into a systematic whole. It was translated into Latin and read as a core textbook in European universities until the 17th century. It also contains rules for the spread of contagious disease and for testing new drugs.
c. 1027
Ibn Sīnā and the Book of Healing · Philosophy
Ibn Sīnā's encyclopedic Book of Healing (Kitāb al-Shifāʾ) covers logic, physics, mathematics and metaphysics. He sought to ground God's existence by reason with the argument from the necessary existent. He is also famous for the "flying man" thought experiment, which says that a person blindfolded and suspended in empty space would still be aware of their own existence.
1095
Al-Ghazālī's Incoherence of the Philosophers · Kalām (Islamic theology)
In this work al-Ghazālī criticised, on twenty issues, the Peripatetic philosophy represented by Ibn Sīnā and al-Fārābī, arguing that the philosophers' views rest on conjecture rather than demonstration. He criticised the philosophers sharply on the eternity of the world, God's not knowing particulars and the denial of bodily resurrection. In the seventeenth discussion he argued that causality is not necessary.
c. 1105
Kīmiyā-yi Saʿādat (The Alchemy of Happiness) · Sufism (taṣawwuf)
In this work written in Persian, al-Ghazālī uses the notion of alchemy in a spiritual sense: just as alchemists try to turn copper into gold, a person can reach a heart "like gold" by purifying the self. It is an example of how the material and spiritual aspects of alchemy interweave in Islamic thought.
c. 1108
Al-Ghazālī's Deliverance from Error · Sufism (taṣawwuf)
In this autobiographical work al-Ghazālī describes losing trust in the senses and in reason in his search for certain knowledge, passing through methodical doubt some five centuries before Descartes. After examining theology, philosophy and the Bāṭiniyya, he says he reached certainty on the Sufi path, through experience ("dhawq", taste).
c. 1180
Ibn Rushd and The Incoherence of the Incoherence · Philosophy
Ibn Rushd answered al-Ghazālī's critique of the philosophers, The Incoherence of the Philosophers, with The Incoherence of the Incoherence. He defended causality, holding that fire burns cotton because of the nature of fire, and argued that philosophical reflection is religiously required. A movement called Averroism arose in the Latin world.
1210
Fakhr al-Dīn al-Rāzī and the meeting of kalām and philosophy · Kalām (Islamic theology)
Fakhr al-Dīn al-Rāzī (1149–1210) re-examined Ashʿarī kalām with the concepts and methods of Avicenna's philosophy. He wrote on kalām, philosophy, Qur'an commentary, legal theory, medicine and astronomy. His great commentary, Mafātīḥ al-ghayb, explains the verses through extensive theological and philosophical discussion. His critical commentary on Avicenna's Ishārāt, together with Ṭūsī's defence, started a debate that was read for centuries.
June 1215
Magna Carta · Law and politics
In 1215 King John of England accepted a document limiting royal power in an agreement with rebel barons. Its most famous clause says that no free man may be punished except by lawful judgement. The Pope annulled it within months, but it was reissued in later years and became a symbol of the rule of law.
c. 1229
Ibn ʿArabī and the unity of being · Sufism (taṣawwuf)
The views of the Andalusian Sufi Ibn ʿArabī were later called "waḥdat al-wujūd" (the unity of being): true being belongs to God alone, and everything in the world is a manifestation of God's names and attributes. The view had a deep influence in the Islamic world and also sparked fierce debate.
c. 1270
Yggdrasil, the Norse world tree · Mythology
In Norse mythology Yggdrasil is a giant ash tree connecting the nine worlds. Its roots reach into different worlds, and at the foot of one of them lies Mímir's well, for whose wisdom Odin gave an eye. This site's design, showing knowledge as branches and roots, is inspired by this image.
c. 1270
Hacı Bektaş Veli · Sufism (taṣawwuf)
Hacı Bektaş Veli is a 13th-century Sufi who came from Khorasan to Anatolia and settled at Sulucakarahöyük (today Hacıbektaş) near Kırşehir. The Alevi and Bektashi traditions regard him as their "pir". Most of what is known about his life rests on the Vilâyetnâme, written about two centuries after his death. The Bektashi order that bears his name is held to have been institutionalised later, not founded by him.
1273
Rūmī and the Masnavi · Sufism (taṣawwuf)
The Masnavi, the Persian work of about 25,000 couplets by Rūmī, who lived in Konya, conveys Sufi teachings through stories. It opens with the lament of the reed flute for its separation from its origin and its longing to return. The work is among the most read and commented-on works of Islamic culture and reaches a wide readership worldwide today.
1377
Ibn Khaldūn's Muqaddimah · Society, history and economics
Ibn Khaldūn studied history not merely as a sequence of events but together with the causes that explain the rise, ascendancy and decline of societies. He called the solidarity that holds a group together "ʿaṣabiyya" and argued that dynasties rise and fall in about three generations. Some authors regard him as a forerunner of sociology and economics; others think this reads him through modern concepts.
1435
Linear perspective · Art, music and aesthetics
In the Renaissance Brunelleschi and Alberti developed linear perspective, depicting the three-dimensional world realistically on a two-dimensional surface by geometric rules; Alberti wrote the rules down in 1435. The art historian Hans Belting argued that Latin translations of Ibn al-Haytham's works on vision and light played a role in this development.
c. 1437
Ulugh Beg and the Samarkand Observatory · Astronomy and cosmology
The Timurid ruler and astronomer Ulugh Beg founded one of the largest observatories of the age in Samarkand. The Zīj of Ulugh Beg, prepared from its observations, gave newly measured positions for about 1,000 stars; the tables were used in the Islamic world and Europe until the invention of the telescope. Ali Qushji, who worked at the observatory, later came to Istanbul and influenced the teaching of astronomy and mathematics in the Ottoman Empire.
c. 1455
Movable-type printing · Technology and engineering
In Mainz in the 1450s Johannes Gutenberg combined metal movable type, oil-based ink and a printing press. The Gutenberg Bible, printed around 1455, is the first major work of this method. In China Bi Sheng had used fired-clay movable type in the 1040s, and in Korea a book was printed with metal type in 1377. How far printing shaped the Scientific Revolution and the Reformation is debated. The first Ottoman Turkish press was set up in 1727 by İbrahim Müteferrika.

1500–1800

1543
Copernicus and the heliocentric model · Astronomy and cosmology
In 1543 Copernicus published his model placing the Sun at the centre and the Earth as a planet orbiting it yearly. Initially the model did not give more accurate predictions than Ptolemy's. That some of Copernicus's geometric techniques closely resemble models of the Maragha school in the Islamic world is debated among historians.
1557
Mimar Sinan and the Süleymaniye · Art, music and aesthetics
As chief architect of the Ottoman Empire in the 16th century, Mimar Sinan designed hundreds of buildings over some 50 years. The Süleymaniye Mosque and complex, built for Suleiman the Magnificent, was completed in 1557. The mosque was conceived as a city centre together with madrasas, a hospital, a soup kitchen and a bath. According to the texts recording his memoirs, Sinan himself called the Şehzade his apprentice work, the Süleymaniye his journeyman work and the Selimiye in Edirne his masterpiece.
1604
Sikhism and the Guru Granth Sahib · Religions and scriptures
Sikhism emerged in the Punjab in the late 15th century with the teaching of Guru Nanak (1469–1539). It believes in one formless God. It rests on remembering God, honest work and sharing, and rejects caste distinctions. The first compilation of its scripture, the Guru Granth Sahib (Adi Granth), was made by Guru Arjan in 1604. After the tenth guru, Gobind Singh, the text came to be regarded as the community's eternal guru.
1609
Kepler's laws · Astronomy and cosmology
Using Tycho Brahe's precise observations of Mars, Kepler found that planetary orbits are ellipses, not circles. His three laws describe how a planet's speed and orbital period vary with its distance from the Sun. Newton later derived them from the law of gravitation. While doing this work Kepler also served as a court astrologer.
1624
Aḥmad Sirhindī and the unity of witnessing · Sufism (taṣawwuf)
Aḥmad Sirhindī (1564–1624), who lived in India, is known by the titles "Imām-i Rabbānī" and "renewer of the second millennium". He founded the Mujaddidī branch of the Naqshbandiyya. Against the unity of being (waḥdat al-wujūd) attributed to Ibn ʿArabī he developed the view of the unity of witnessing (waḥdat al-shuhūd). His letters, the Maktūbāt, had wide influence in the Ottoman world as well.
1628
The circulation of the blood · Medicine
According to Galen, blood was continually produced in the liver and consumed in the body. In 1628 William Harvey, by calculating the amount of blood the heart pumps, argued that blood circulates continuously in a loop. The pulmonary circulation had been described in the 13th century by the Damascene physician Ibn al-Nafīs.
1637
Descartes and methodical doubt · Philosophy
To reach certain knowledge Descartes proposed doubting everything that can be doubted, and concluded that as a thinking being who doubts he cannot doubt his own existence: "I think, therefore I am." He argued that mind and body are two distinct substances, placing the "mind–body problem" at the centre of modern philosophy.
1651
Social contract theories · Law and politics
According to social contract theories the state gains legitimacy from an agreement people make among themselves. For Hobbes life without the state is "solitary, poor, nasty, brutish, and short", so people submit to a strong sovereign. Locke defended a right to resist government that fails to protect life, liberty and property. Rousseau held that sovereignty lies in the people's "general will".
1661
Boyle and "The Sceptical Chymist" · Chemistry
Robert Boyle questioned Aristotle's four elements and Paracelsus' three principles through experiment and argued that matter consists of small particles. He is usually counted among the founders of modern chemistry. It is also known that he pursued alchemical work on transmuting metals into gold until his death.
c. 1669
Newton's alchemical work · Esoteric traditions
Newton, one of the founders of modern physics, secretly studied alchemy for about thirty years and left more than a million words of notes on it. When these manuscripts were auctioned in 1936, the economist Keynes called Newton "not the first of the age of reason, but the last of the magicians". Historians debate how far this work influenced Newton's physics.
1684
Calculus · Mathematics
Calculus, which lets us compute change and accumulation, is the language of physics and engineering. Whether Newton and Leibniz developed it independently was argued over for a long time. Some historians also point to earlier work on infinite series by the Kerala school in India.
1687
Newton's Principia · Physics
With three laws of motion and the law of universal gravitation, Newton explained a falling apple and the orbits of the planets with the same rules. The theory was the foundation of physics for two centuries. It still works very well at everyday speeds and in weak gravity, but in some cases, such as Mercury's orbit, its predictions differ from general relativity.
1703
Phlogiston theory · Chemistry
In the 18th century combustion was explained as the release of a principle called "phlogiston" from a substance. Lavoisier's theory that combustion is combination with oxygen from the air replaced this explanation. Some historians of science argue that phlogiston theory had real explanatory power in its day and was abandoned too quickly.
1748
Montesquieu and the separation of powers · Law and politics
Montesquieu argued that to preserve liberty the legislative, executive and judicial powers must be in different hands; if they are concentrated in one person or body, oppression is inevitable. The idea influenced the US Constitution and most modern constitutions.
1763
Bayes' theorem and reasoning with probability · Mathematics
Thomas Bayes's essay, published after his death in 1763 by Richard Price, offered a method showing how confidence in a hypothesis should be updated when new evidence arrives. Laplace developed and generalised the idea independently. Today Bayes' theorem is used widely, from medical diagnosis and artificial intelligence to debates on scientific method and the weighing of evidence in courts. What probability means, however, is debated.
1769
The steam engine · Energy
The steam engine, which turns the heat of coal into motion, became the engine of the Industrial Revolution. Newcomen's 1712 engine pumped water out of mines. The separate condenser patented by James Watt in 1769 greatly reduced fuel consumption.
1776
Adam Smith and The Wealth of Nations · Society, history and economics
Adam Smith argued that the division of labour greatly increases productivity and that individuals pursuing their own interest in a competitive market unwittingly serve the general good of society (the "invisible hand"). The work is regarded as the beginning of modern economics. Whether his ideas can be read apart from his moral philosophy is debated.
1781
Kant and the Critique of Pure Reason · Philosophy
Kant argued that knowledge arises from both experience and structures the mind brings beforehand (space, time and categories such as causality). We therefore know things not as they are "in themselves" but as they appear to our minds. He held that reason cannot reach certain knowledge beyond experience about God, the soul and the world as a whole.
1789
Utilitarianism and consequentialist ethics · Philosophy
According to utilitarianism, whether an action is right depends on how much its consequences increase the total happiness of everyone. Bentham expressed this as "the greatest happiness of the greatest number". Mill argued that pleasures differ in quality. The view has shaped debates on animal rights and global poverty. Critics argue that individual rights could be sacrificed for the sake of total welfare.
1789
Lavoisier and the conservation of mass · Chemistry
Lavoisier showed by careful weighing that in chemical reactions matter is neither created nor destroyed and total mass is conserved. He explained combustion as combination with oxygen and reorganised chemical nomenclature. In 1794, during the French Revolution, he was guillotined for his role as a tax farmer.
1798
Vaccination · Medicine
In 1796 Jenner showed that a boy inoculated with cowpox was protected against smallpox, and published his results in 1798. The Ottoman practice of variolation had earlier been brought to England by Lady Montagu. In 1980 the World Health Organization declared smallpox eradicated.

1800–1900

1808
Atomic theory · Chemistry
Dalton argued that each element consists of indivisible atoms of characteristic weight and that compounds form when atoms combine in simple ratios. Many scientists regarded atoms only as a useful calculating device until the early 20th century. Einstein's 1905 explanation of Brownian motion and Perrin's measurements of 1908–1909 were decisive in that debate. The idea of atoms also appears in other forms in ancient Greece and in Islamic kalām.
1809
Lamarck and the inheritance of acquired characteristics · Biology
Lamarck argued that living things become more complex over time and that the development of an organ through use, or its withering through disuse, is passed to offspring. This view was largely abandoned in the 20th century. Recent work on epigenetic inheritance has led some researchers to discuss Lamarck again.
1810
Homeopathy · Medicine
Homeopathy, systematised by Hahnemann in 1810, rests on the principle "like cures like" and on the idea that substances gain potency by extreme dilution and shaking. It is widely used in many countries. Meta-analyses have reached differing conclusions on whether its effects differ from placebo.
August 1831
Electromagnetic induction and electricity generation · Energy
In 1831 Faraday discovered that a changing magnetic field produces an electric current in a wire. Almost every power station today generates electricity on this principle by turning turbines. Transformers and electric motors rest on the same principle.
1839
Cell theory · Biology
The view that all living things are made of cells and that every cell comes from another cell. Hooke saw "cells" in cork in 1665. Schleiden and Schwann argued in 1838–1839 that plants and animals are made of cells. Virchow added the principle "every cell from a cell" in 1855.
1843
Babbage, Lovelace and the Analytical Engine · Computing and artificial intelligence
Charles Babbage designed an "Analytical Engine" programmable with punched cards and structurally similar to today's computers, but it was never completed. In her 1843 notes on the machine Ada Lovelace gave a method for computing Bernoulli numbers, often called the "first computer program". How large her contribution was is debated among historians.
1850
The laws of thermodynamics · Energy
Energy cannot be created or destroyed, only changed in form (first law). Heat does not flow by itself from cold to hot, and no engine can turn all heat into work (second law). These laws set the limits of every machine from the steam engine to the refrigerator.
1859
The Riemann hypothesis (open) · Mathematics
The most famous unproven conjecture, open since 1859, concerning the distribution of prime numbers. It has been checked by computer in trillions of cases with no counterexample, but in mathematics this does not count as a proof. It is one of the Clay Institute's Millennium Problems.
November 1859
Darwin and Wallace, natural selection · Biology
Darwin and Wallace independently arrived at the idea that individuals of a species differ in heritable ways, that those better suited to their surroundings leave more offspring, and that species therefore change and diverge over time. Darwin published "On the Origin of Species" in 1859. Darwin himself recorded the scarcity of intermediate forms in the fossil record as one of the main difficulties facing his theory.
1865
Maxwell's equations and light · Physics
Maxwell unified electricity and magnetism in a single theory and calculated that electromagnetic waves should travel at the speed of light. From this he concluded that light is an electromagnetic wave. Hertz produced such waves experimentally in 1887–1888. This is the basis of radio, television and wireless communication.
1866
Mendel and the laws of inheritance · Biology
Working in a monastery in Brno, Mendel showed with pea crosses that traits pass from generation to generation as discrete "units" rather than by blending. His work went largely unnoticed until it was rediscovered in 1900. The statistician Fisher later argued that Mendel's data were "too good" to be expected.
1867
Marx and Capital · Society, history and economics
Marx argued that the capitalist economy rests on "surplus value" extracted from workers' labour, that history advances through conflicts between classes, and predicted that capitalism would give way to a classless society because of its own contradictions. His ideas inspired political movements that shaped much of the world in the 20th century; whether his predictions came true is still debated.
1869–1876
The Mecelle (Ottoman civil code) · Law and politics
The Mecelle-i Ahkâm-ı Adliyye was prepared in the Ottoman Empire between 1868 and 1876 by a commission headed by Ahmed Cevdet Pasha. It is a code setting out, in numbered articles, the law of obligations, property and procedure based on Ḥanafī fiqh, and is regarded as the first major attempt to write Islamic law in the form of a modern code. In Turkey it was replaced in 1926 by a Civil Code adopted from Switzerland.
1869
The periodic table · Chemistry
Mendeleev arranged the elements by atomic weight and properties and showed that properties recur at regular intervals. He left gaps in the table and predicted the properties of elements not yet discovered. Gallium, scandium and germanium were found in the following years.
1874
Cantor and the sizes of infinity · Mathematics
Cantor showed that infinities can be larger than one another: the natural numbers and the real numbers are both infinite, but the reals are "more". Some mathematicians such as Kronecker opposed the idea fiercely; Hilbert said that "no one shall expel us from the paradise that Cantor has created". Cantor also related his thinking on infinity to theological questions.
1876
Germ theory of disease · Medicine
Until the mid-19th century many diseases were thought to spread through "bad air" (miasma). Semmelweis's hand-washing observations, Snow's cholera map, Pasteur's experiments and Koch's identification of the anthrax and tuberculosis bacteria established the view that specific microorganisms cause specific diseases.
1879
Frege and the birth of modern logic · Philosophy
With the Begriffsschrift ("concept script") of 1879 Frege rebuilt a logic that had changed little since Aristotle. He treated quantifiers such as "every" and "some" within a complete system for the first time. His aim was to show that arithmetic can be derived from pure logic. In 1902 Russell found a contradiction in the system and the programme could not continue in that form, but the logic he developed became a basic tool of today's mathematics and computer science.
1882
Nietzsche and the revaluation of values · Philosophy
In The Gay Science (1882) Nietzsche used the phrase "God is dead" to argue that Christian belief in Europe could no longer carry morality and meaning. He thought this could lead to a void of meaning, nihilism. He held that humans must create their own values. After his death his works were read in very different ways, shaped by his sister's editing and by political aims.
1888
The neuron doctrine · Psychology and mind
From 1888 on, Santiago Ramón y Cajal argued from microscope studies that the nervous system is made of separate cells, neurons. Camillo Golgi, by contrast, thought the nervous system was a continuous network. The two shared the 1906 Nobel Prize in Physiology or Medicine and defended opposing views at the ceremony. In the 1950s the electron microscope showed the synaptic gap between neurons, but it was also found that some cells are joined by direct electrical connections.
1896
The greenhouse effect · Earth sciences
In 1856 Eunice Foote showed that a vessel filled with carbon dioxide warms more in the sun than one filled with air. In 1861 Tyndall measured the absorption of infrared heat by water vapour and carbon dioxide. In 1896 Arrhenius calculated that doubling atmospheric CO₂ would warm the Earth by several degrees. Without the greenhouse effect the Earth's average temperature would be far below freezing.
November 1899
Psychoanalysis · Psychology and mind
Freud argued that much of our behaviour is shaped by unconscious desires and childhood experiences, and saw dreams as a road to the unconscious. Psychoanalysis became very influential in culture, art and therapy. Its scientific testability is disputed; Popper cited it as an example of an unfalsifiable theory.

1900–2000

1900
Phenomenology · Philosophy
Phenomenology is a philosophical method that tries to describe experience from the first-person point of view, as it appears to us. It is taken to begin with Husserl's Logical Investigations, published in 1900–1901. Central to it is the idea that consciousness is always consciousness of something, that it is directed at something. Heidegger and Merleau-Ponty carried the method to questions of being, the body and perception.
December 17, 1903
Powered flight and the aeroplane · Technology and engineering
On 17 December 1903 the Wright brothers took off near Kitty Hawk, North Carolina, in a powered, controllable aeroplane; the first flight lasted 12 seconds. In Brazil, however, Alberto Santos-Dumont is regarded as the first to fly, with his 14-bis, which took off under its own power in Paris in 1906 in front of the public and official observers. The disagreement depends on which criteria are required for a "first flight".
1905
Special relativity · Physics
Einstein started from two assumptions: the laws of physics are the same for everyone in uniform motion, and the speed of light in vacuum is the same for everyone. From these it follows that fast-moving clocks run slow, lengths contract and mass and energy are equivalent (E = mc²).
1913
The Haber–Bosch process and synthetic fertiliser · Chemistry
In 1909 Haber succeeded in producing ammonia from atmospheric nitrogen, and in 1913 Bosch scaled the process up to industry. Fertilisers made this way now make possible the farming that feeds roughly half the world's population. The same chemist, Haber, also led the development of poison-gas weapons in the First World War.
1915
Continental drift and plate tectonics · Earth sciences
In 1915 Wegener proposed that the continents were once joined and are slowly drifting apart. Because he could show no mechanism to move them, his view was largely rejected for some 40 years. With the discovery of magnetic stripes on the sea floor in the 1960s, plate tectonics came to be accepted. Earthquakes in Turkey are explained by this theory too.
November 1915
General relativity · Physics
According to Einstein, gravity is not a force but the curving of spacetime by mass and energy. Bodies follow the most natural paths in this curved spacetime. The theory predicts the bending of light near massive bodies, black holes, gravitational waves and the clock differences that GPS satellites must correct for.
1916
Saussure and structural linguistics · Linguistics
Saussure defined language as a system of signs that gain meaning through their relations with one another. For him the link between a word's sound and its meaning is not natural but conventional (arbitrary). His book, compiled from his students' lecture notes, launched 20th-century structuralism in linguistics, anthropology and literary theory.
1921
Wittgenstein, language and meaning · Philosophy
Wittgenstein argued that many problems of philosophy arise from misunderstanding language. In his first book, the Tractatus (1921), he held that a meaningful proposition is a picture of a state of affairs in the world. In the Philosophical Investigations, published after his death (1953), he criticised this view himself: the meaning of a word is its use in the language. The two periods of the same thinker are read as two distinct paths in the philosophy of language.
1925
The p-value and the statistical significance debate · Mathematics
In scientific studies the threshold p < 0.05 is usually used to count a result as "statistically significant". The tradition rests largely on Ronald Fisher's book of 1925. After the replication crisis it became widely debated that p-values are misinterpreted and that tying conclusions to a single threshold leads to misleading results. The American Statistical Association issued a statement on the matter in 2016. Researchers disagree on the proposed remedies.
1926
Quantum mechanics · Physics
In the atomic and subatomic world, energy is exchanged in packets (quanta) and the results of measurements can be predicted only as probabilities. The theory underlies modern technology from semiconductors to lasers. Physicists still hold different interpretations of what measurement and the "wave function" really mean.
1927
The beginning of the universe and the Big Bang · Astronomy and cosmology
In 1927 Lemaître proposed that the universe is expanding and emerged from a very dense, hot initial state in the past. Hubble's measurement of galaxies receding and the discovery of the cosmic microwave background in 1965 supported this view; Hoyle and others advocated a "steady state" universe without a beginning. The creation narratives of religions describe the beginning of the universe in different ways.
1927
The Copenhagen interpretation · Physics
Based on the views of Bohr and Heisenberg in the 1920s, the Copenhagen interpretation is the most widely taught. Quantum theory gives the probabilities of measurement results rather than what is observed "in itself". A measurement is made with an apparatus described classically and yields a single result. According to the principle of complementarity, wave and particle descriptions are mutually exclusive yet jointly necessary perspectives. The interpretation has no single, definitive form.
1929
Penicillin and antibiotics · Medicine
In 1928 Fleming noticed that a mould contaminating a bacterial culture killed the bacteria, and published this in 1929. Florey and Chain's team made penicillin producible as a drug in the 1940s. Antibiotics have saved millions of lives; today bacterial resistance to these drugs is seen as a major global problem.
1931
Gödel's incompleteness theorems · Mathematics
Gödel proved that in every consistent formal system strong enough to include arithmetic there are statements that are true but cannot be proved within the system. Such a system also cannot prove its own consistency. The result changed the hope of placing all of mathematics on a complete formal foundation (Hilbert's programme).
1933
Dark matter · Astronomy and cosmology
Galaxies and galaxy clusters rotate and move faster than the gravity of visible matter can explain. Most astronomers explain this with invisible "dark matter", but despite decades of searches its particles have not been detected directly. A minority argues that the law of gravity works differently at very weak accelerations (MOND).
1934
Popper and falsifiability · Philosophy
For Popper a scientific theory can never be conclusively verified, only falsified. What makes a theory scientific is that it says in advance which observation would refute it. He cited Einstein's relativity as fitting this criterion, and Freud's psychoanalysis and Marx's theory of history as not fitting it.
1934
Rhine and the extrasensory perception experiments · Parapsychology
J. B. Rhine carried out thousands of guessing trials with five-symbol Zener cards at Duke University and reported more hits than chance would predict. He popularised the term "extrasensory perception" (ESP). Critics pointed to problems such as cards being visible from the back, poor shuffling and statistical errors.
1935
The ecosystem concept and ecology · Biology
In 1935 the British botanist Arthur Tansley proposed the term "ecosystem" to treat living things and their physical surroundings as a single system. This approach made it possible to study forests, lakes and seas through energy flow and nutrient cycles. In the second half of the 20th century ecology became both a scientific discipline and a body of knowledge on which environmental policy rests.
1936
The Turing machine and computability · Computing and artificial intelligence
In 1936 Turing defined an abstract machine able to imitate any mechanical calculation, and with it proved that there are problems no algorithm can solve, the best known being whether a program will halt (the halting problem). This idea is the theoretical basis of today's computers.
1939
Nuclear fission · Energy
At the end of 1938 Hahn and Strassmann found barium when they bombarded uranium with neutrons. Meitner and Frisch explained this as the uranium nucleus splitting in two and releasing a large amount of energy. The discovery became the basis of both nuclear power plants and the atomic bomb. Meitner's contribution was not recognised by the Nobel Prize.
1942
The modern synthesis (neo-Darwinism) · Biology
In the 1930s and 1940s Darwin's natural selection and Mendelian genetics were united through mathematical population genetics. In this framework evolution is the change of gene frequencies in populations through mutation, selection, drift and migration. In 1942 Julian Huxley named this union the "modern synthesis".
1943
Existentialism · Philosophy
Existentialism is a current of thought holding that humans have no predetermined essence and define who they become through their own choices. Sartre summed this up as "existence precedes essence". Freedom, responsibility, anxiety and the search for meaning are its main themes. Kierkegaard's existentialism was religious, Sartre's atheist.
December 1947
The transistor · Computing and artificial intelligence
The first transistor, built at Bell Laboratories in December 1947, was a small semiconductor device that amplifies and switches electrical signals. Today's processors contain tens of billions of transistors on a fingertip-sized chip. The doubling of transistor counts roughly every two years is known as "Moore's law".
1948
Information theory · Computing and artificial intelligence
In 1948 Shannon made information measurable in units of "bits" and calculated the maximum amount of information that can be sent without error over a noisy channel. The work underlies all digital communication, from the internet and mobile phones to data compression and space communication.
December 10, 1948
The Universal Declaration of Human Rights · Law and politics
On 10 December 1948 the UN General Assembly adopted the 30-article declaration proclaiming that all human beings are born free and equal in rights. Whether these rights are universal has been debated. In 1990 the Organisation of Islamic Cooperation adopted the Cairo Declaration on Human Rights in Islam, which defines rights within the framework of Islamic law.
1952
Pilot-wave theory (de Broglie–Bohm) · Physics
According to this theory, put forward by de Broglie in 1927 and developed by Bohm in 1952, particles always have definite positions and are guided by a wave obeying the Schrödinger equation. The theory is deterministic; probabilities come only from our ignorance of initial positions. It gives the same predictions as standard quantum mechanics but is explicitly non-local: the motion of a distant particle depends instantly on what happens elsewhere.
1952
The electrical model of the nerve impulse (Hodgkin–Huxley) · Psychology and mind
Measuring on the giant axon of the squid, Hodgkin and Huxley showed that the nerve impulse (action potential) arises from the movement of sodium and potassium ions across the membrane. The mathematical model they published in 1952 correctly predicted the shape and speed of the signal and remains one of the basic tools of neuroscience. They received the 1963 Nobel Prize in Physiology or Medicine. The ion channels they inferred were measured one by one in 1976.
April 1953
The double-helix structure of DNA · Biology
In 1953 Watson and Crick proposed that DNA, the molecule of heredity, is a double helix of two intertwined strands. The structure explained how DNA can copy itself. Rosalind Franklin's X-ray diffraction data were decisive in building the model; they had been shared without her knowledge.
1954
The silicon solar cell · Energy
In 1954 Bell Laboratories introduced the first practical silicon solar cell, converting sunlight directly into electricity with about 6% efficiency. Solar panels are now the world's fastest-growing source of electricity. In 2025 solar alone met more than a quarter of the growth in global energy demand.
1955
The placebo effect · Medicine
A pill without active ingredient or a sham treatment can be associated with reduced symptoms in some patients; this is called the placebo effect. It is the main reason new treatments are tested against placebo. How strong the placebo effect is remains disputed; part of it can be explained by natural recovery and measurement biases.
1957
Chomsky and universal grammar · Linguistics
Chomsky explained children's ability to learn language quickly from limited examples by an innate "universal grammar" in humans. The view profoundly influenced linguistics and cognitive science. Critics argue that language is learned through general learning abilities and use. The claim that the Amazonian language Pirahã lacks recursion, a supposed core universal, became central to the debate.
1957
The many-worlds interpretation (Everett) · Physics
In 1957 Hugh Everett proposed that the wave function never collapses. The Schrödinger equation always holds and every possible outcome of a measurement occurs. Everything, including the observer, splits into "branches" in which different outcomes happen and which do not interact. The interpretation is defended for adding no collapse postulate to the theory; critics object to its acceptance of countless unobservable worlds and question how probability is to be understood.
October 4, 1957
Sputnik 1 and Gagarin · Space exploration
On 4 October 1957 the Soviet Union launched the first artificial satellite, Sputnik 1. On 12 April 1961 Yuri Gagarin orbited the Earth once in Vostok 1, becoming the first human in space. These achievements accelerated the founding of NASA and the goal of reaching the Moon in the US.
1958
The Keeling curve · Earth sciences
In 1958 Charles Keeling began continuous measurements of atmospheric carbon dioxide at the Mauna Loa Observatory in Hawaii. The measurements show a steady rise together with a yearly up-and-down linked to the plant growing season. CO₂ concentration was about 315 ppm in 1958 and exceeded 420 ppm in 2024.
1961
Creationism · Biology
Creationism holds that living species (or basic "kinds") were created directly and separately by God. Young-earth creationism, based on a literal reading of scripture, holds that the Earth is a few thousand years old; old-earth creationism accepts geological ages but maintains that species were created separately. In Turkey, too, creationism has been advocated in widely circulated publications, especially since the 1990s.
1962
Silent Spring and pesticides · Biology
Rachel Carson's Silent Spring, published in 1962, described the effects of pesticides such as DDT on birds, fish and the food chain. The book started a broad public debate and is counted among the starting points of the modern environmental movement. The US banned the agricultural use of DDT in 1972. The benefits of limited DDT use against malaria and its health risks are still debated.
1962
Kuhn and paradigm shifts · Philosophy
Kuhn argued that science does not progress by linear accumulation. In periods of "normal science" scientists work within an accepted framework (paradigm); when unexplained anomalies accumulate a crisis arises and a "scientific revolution" leads to a new paradigm. He cited the Copernican and Einsteinian revolutions as examples.
1963
Milgram's obedience experiments · Psychology and mind
In Milgram's experiments participants were told to give increasingly strong electric shocks to a "learner" for wrong answers. The shocks were not real, but the participants did not know that. In the first experiment 65% of participants continued to the maximum 450 volts. The results were read as evidence of how far ordinary people will go in obeying authority. Archival research raised serious questions about how the experiments were conducted.
1964
The Kardashev scale · Energy
The Soviet astronomer Kardashev classified civilisations by the energy they use: Type I uses the energy of a planet, Type II that of a star, Type III that of a galaxy. By the formula Carl Sagan proposed for intermediate values, humanity stands at about 0.73 on 2025 energy data.
1967
The Standard Model · Physics
The theory describing the known elementary particles (quarks, leptons) and three of the four fundamental interactions, all except gravity. It predicts the great majority of experiments to date with very high precision. It does not include gravity, dark matter or neutrino masses.
1968
The neutral theory · Biology
Kimura proposed that most changes at the molecular level (in DNA and protein sequences) arise not by selection but by the random spread (genetic drift) of mutations that are neither beneficial nor harmful. The theory arose as a challenge to the role of Darwinian selection at the molecular level. Debates about how pervasive selection is continue today.
July 20, 1969
Apollo 11 and the Moon landing · Space exploration
On 20 July 1969 Neil Armstrong and Buzz Aldrin became the first humans to walk on the Moon. In six Apollo missions from 1969 to 1972, 12 astronauts walked on the Moon and brought back 382 kg of lunar rock. Some people claim that the landings were staged; retroreflectors left on the surface, the returned samples and photographs taken from orbit are cited as evidence of the landings.
October 29, 1969
The internet and the Web · Technology and engineering
On the ARPANET, the forerunner of the internet, the first message was sent from UCLA to Stanford on 29 October 1969. The idea of packet switching, splitting data into small packets, was developed independently by Paul Baran in the US and Donald Davies in the UK. TCP/IP, described by Cerf and Kahn in 1974, made it possible to connect different networks. Tim Berners-Lee proposed the World Wide Web at CERN in 1989, and the Web became the most common way of using the internet.
1972
Punctuated equilibrium · Biology
Eldredge and Gould argued that in the fossil record species remain almost unchanged for long periods (stasis), and that change happens in geologically short bursts associated with speciation. In their view the scarcity of intermediate forms reflects the real tempo of evolution rather than gaps in the record. The idea was debated as a challenge to Darwin's notion of slow, gradual change.
1974
Ganzfeld telepathy experiments · Parapsychology
In ganzfeld experiments a "receiver", with eyes covered and listening to white noise, tries to identify from four options the image a "sender" in another room is viewing. Chance gives a 25% hit rate. Some meta-analyses reported about 32% hits; others found the effect at chance level.
1976
The four colour theorem and computer-assisted proof · Mathematics
In 1852 it was conjectured that every map can be coloured with at most four colours so that neighbouring countries differ. Appel and Haken proved it in 1976, but part of the proof relied on computer calculations too long for a human to check by hand. This started the debate over whether a computer calculation counts as a proof. In 2005 the proof was formally verified end to end with the Coq proof assistant.
1976
Ice ages and Milankovitch cycles · Earth sciences
The Serbian mathematician Milanković proposed that slow changes in the Earth's orbit and axial tilt, occurring in cycles of tens of thousands of years, trigger ice ages. In 1976 cycles of 100,000, 41,000 and 23,000 years were found in climate records from ocean sediments. Why the 100,000-year cycle dominates over the last 800,000 years is still not fully explained.
1981
Making gold by nuclear transmutation · Physics
Turning one element into another, an old goal of the alchemists, became possible with nuclear physics. Seaborg's team converted bismuth into gold in an accelerator in 1980. In 2025 the ALICE experiment at CERN measured gold being produced when lead nuclei graze past one another in collisions. In both cases the amount is tiny and the cost enormous.
1983
Modified Newtonian dynamics (MOND) · Astronomy and cosmology
In 1983 Mordehai Milgrom proposed that the rotation speeds of galaxies could be explained not by invisible matter but by a law of gravity that works differently at very weak accelerations. MOND predicts galaxy rotation curves from the visible matter alone with striking success. By contrast it struggles with galaxy clusters and the cosmic microwave background. Recent tests with wide binary stars have given opposing results.
1984
Cold dark matter (the ΛCDM model) · Astronomy and cosmology
On this view about four-fifths of the matter in the universe consists of slow-moving ("cold") particles that do not interact with light. Together with dark energy (Λ) it forms the standard model of cosmology (ΛCDM). The model successfully explains the cosmic microwave background, the large-scale distribution of galaxies and observations such as the Bullet Cluster. Despite decades of searching, however, dark matter particles have not been detected directly in the laboratory.
1985
Macroscopic quantum tunnelling in an electric circuit (Nobel 2025) · Physics
Quantum effects are usually seen in single atoms. In 1984–1985 Clarke, Devoret and Martinis showed that a superconducting circuit large enough to hold in the hand tunnels quantum-mechanically as a whole and has discrete energy levels. This work underlies today's superconducting quantum computers. It received the 2025 Nobel Prize in Physics.
1986
Objective-collapse theories (GRW, Diósi–Penrose) · Physics
According to these theories the wave function collapses spontaneously through a physical process independent of any observer. For a single particle such collapse is very rare, but in large objects made of many particles it happens almost instantly, which explains why everyday objects are always found in one place. Unlike other interpretations they predict small deviations from standard quantum mechanics, so they can be tested by experiment.
1988
Global (neuronal) workspace theory · Psychology and mind
According to this theory many specialised processes run in the brain at the same time and outside awareness. Information becomes conscious when it is broadcast to wide areas of the brain at once, that is, when it enters a shared "workspace". Baars proposed the theory in 1988 using a theatre metaphor. Dehaene and colleagues turned it into a model based on long-range neurons linking frontal and parietal regions in particular.
March 1989
Cold fusion (low-energy nuclear reactions) · Energy
In 1989 Fleischmann and Pons announced that they had measured excess heat, not explainable by chemistry, in an electrolysis cell with a palladium electrode at room temperature, and that it might come from nuclear fusion. Many laboratories could not reproduce the result. A group of researchers continues the work under the name "LENR".
1990
Functional magnetic resonance imaging (fMRI) · Psychology and mind
fMRI indirectly shows which brain regions are more active during a task by measuring changes in blood oxygenation. The BOLD signal it relies on was described in 1990 by Seiji Ogawa and colleagues. By allowing the human brain to be studied without surgery, fMRI transformed cognitive neuroscience. It has also been shown, however, that some statistical methods can give false positives and that repeated measurements in the same person can have low reliability.
1991
The lithium-ion battery · Technology and engineering
Lithium-ion batteries work by lithium ions moving back and forth between two electrodes during charging and discharging. Because they are light and can be recharged many times, they made phones, laptops and electric vehicles possible. The first commercial lithium-ion battery went on sale in 1991. Whittingham, Goodenough and Yoshino shared the 2019 Nobel Prize in Chemistry for this work. The environmental and social effects of cobalt and lithium mining and recycling are important topics of debate.
1995
Fermat's Last Theorem · Mathematics
In 1637 Fermat wrote in the margin of a book that aⁿ + bⁿ = cⁿ has no solution in positive integers for n > 2, and that he had "a marvellous proof". No proof was found for 358 years, until Andrew Wiles published one in 1995.
October 1995
Exoplanets · Astronomy and cosmology
In 1995 Mayor and Queloz found the first planet orbiting a Sun-like star (51 Pegasi). In September 2025 NASA's count of confirmed exoplanets passed 6,000. Some lie in their star's habitable zone, and their atmospheres are being searched for signs of life.
1996
Intelligent design · Biology
According to proponents of intelligent design, some biological structures are so complex that they would not work at all if one part were missing ("irreducible complexity"). They therefore infer that such structures were produced by an intelligent designer rather than by blind, step-by-step processes. Opponents present models showing the stepwise development of these structures and argue that the theory is not scientifically testable. In 2005 a US court held that teaching it as science in public schools was unconstitutional.
1998
Dark energy and accelerating expansion · Astronomy and cosmology
In 1998 distant supernovae appeared fainter than expected, which was interpreted as the expansion of the universe accelerating. The unknown cause was named "dark energy". Data released by DESI in 2025 hinted that dark energy may not be constant but may change over time; this result is not yet settled.

2000 onwards

December 2001
Near-death experiences · Parapsychology
Some patients whose hearts stopped and who were then resuscitated report experiences such as a tunnel, bright light, watching themselves from outside the body and meeting deceased relatives. Some researchers think these point to consciousness possibly being independent of the brain; others explain them by lack of oxygen and activity in particular brain regions. They are also compared with accounts of the afterlife in most religions.
2003
Proof of the Poincaré conjecture · Mathematics
In 1904 Poincaré posed a conjecture characterising three-dimensional "sphere-like" spaces. Grigori Perelman proved it in three papers posted to arXiv in 2002–2003. He declined the Clay Institute's million-dollar prize and the Fields Medal. It is the only Millennium Prize Problem solved to date.
2004
Integrated information theory (IIT) · Psychology and mind
According to this theory, proposed by Giulio Tononi in 2004, consciousness is a system's capacity to generate integrated information over and above its parts. This capacity is measured by a quantity called Φ (phi). On the theory, consciousness is tied to tightly connected structures in posterior regions of the brain and is not unique to brains. Some researchers regard it as a principled theoretical basis for consciousness, while others criticise it on the grounds that its core claims cannot be tested.
2005
Higher-order theories of consciousness · Psychology and mind
According to higher-order theories, a mental state is conscious only when the mind represents that state to itself. Seeing a red apple, for example, becomes conscious only when accompanied by a higher-order representation registering "I am seeing red". The view was developed in philosophy by David Rosenthal; in neuroscience it is proposed that prefrontal regions play a role in this higher-order representation.
2006
Theistic evolution (evolutionary creation) · Biology
According to theistic evolution, God created living things through the evolutionary processes that science describes, and no conflict is seen between science and religion. Francis Collins, former director of the Human Genome Project, and the Catholic Church's official statement of 1996 are examples. Both atheist scientists and creationists criticise the view, for different reasons.
March 2011
The "Feeling the future" experiments · Parapsychology
In 2011 the social psychologist Daryl Bem published nine experiments in one of psychology's most respected journals, reporting that participants "sensed" events that had not yet happened slightly better than chance. Independent replications did not find the effect. The controversy became one of the events that set off psychology's replication crisis.
2012
Deep learning · Computing and artificial intelligence
Artificial neural networks, inspired by nerve cells in the brain, had been studied since the 1950s. In 2012 a many-layered ("deep") network trained on graphics processors beat earlier methods in image recognition by a wide margin, an event regarded as the start of today's wave of AI. Hinton and Hopfield received the 2024 Nobel Prize in Physics for foundational contributions to the field.
June 2012
CRISPR gene editing · Biology
Derived from a defence system bacteria use against viruses, CRISPR-Cas9 made it easy and cheap to cut and change DNA at a chosen site. It was the subject of the 2020 Nobel Prize in Chemistry. In 2023 the first CRISPR therapy was approved for sickle-cell disease. An unauthorised edit of human embryos in 2018 drew international condemnation.
July 2012
Discovery of the Higgs boson · Physics
The Higgs boson, predicted in 1964, was announced on 4 July 2012 by the ATLAS and CMS experiments at CERN's Large Hadron Collider. The particle is the signature of the Higgs field, which is thought to give elementary particles their mass.
August 25, 2012
Voyager and interstellar space · Space exploration
Launched in 1977, Voyager 1 and 2 imaged Jupiter, Saturn, Uranus and Neptune up close. On 25 August 2012 Voyager 1 crossed the edge of the Sun's wind (the heliopause) and became the first human-made object in interstellar space. Both spacecraft are still sending data to Earth today.
2014
QBism (Quantum Bayesianism) · Physics
According to QBism the wave function expresses not the world itself but an agent's personal beliefs about their own future experiences. A measurement is an action the agent takes on the world and the new experience received in return; "collapse" is just the updating of belief with new information. The interpretation reads quantum probabilities within Bayesian probability theory and is one example of epistemic approaches that treat the wave function as information.
2015
The extended evolutionary synthesis · Biology
A group of biologists argues that developmental processes, environment-dependent changes in form, epigenetic inheritance and organisms' modification of their own surroundings (niche construction) play a larger role in directing evolution than assumed, and that the current theory should therefore be extended. Other biologists argue that these phenomena are already accommodated within the existing theory.
August 2015
The replication crisis · Psychology and mind
In 2015, 270 researchers repeated 100 psychology experiments published in respected journals. While 97% of the originals had reported significant results, only about 36% of the replications did. Similar problems were reported in medicine and economics. It became a strong example that scientific findings are not settled by a single study.
February 2016
Direct detection of gravitational waves · Physics
According to general relativity, colliding black holes create ripples in spacetime. On 14 September 2015 the LIGO detectors recorded such a signal from the merger of two black holes 1.3 billion light-years away. The result was announced in February 2016. Hundreds of similar events have been observed since.
June 2017
The Transformer and large language models · Computing and artificial intelligence
The Transformer architecture, proposed in 2017, computes how the words in a text relate to one another with an "attention" mechanism. Large language models such as GPT, Claude and Gemini are built on it. They have shown great progress in writing, translation, programming and reasoning tasks. Whether they really "understand" is debated.
2018
Are new neurons born in the adult human brain? · Psychology and mind
For a long time it was thought that no new neurons form in the adult brain. Animal studies and a human study in 1998 showed that new neurons are born in adulthood in the hippocampus, a region important for memory. A study published in 2018, however, found almost no new neurons in the adult human hippocampus. Other studies the same year and later reported neuron production continuing into old age. The difference in results is largely attributed to tissue preparation and labelling methods.
2019
Biodiversity loss and the "sixth mass extinction" debate · Biology
The 2019 global assessment of IPBES, a UN-linked body, estimated that around one million animal and plant species face extinction. Some researchers argue that today's extinction rate is far above the natural rate and that Earth has entered a sixth mass extinction. Others show that estimates of extinction rates depend heavily on the methods used and that species numbers are not declining everywhere at local scale. The debate is less about whether loss is happening than about its rate and scale.
April 2019
The first image of a black hole · Astronomy and cosmology
General relativity predicts objects so dense that not even light can escape: black holes. In April 2019 the Event Horizon Telescope published the first image of the bright ring around the black hole at the centre of the galaxy M87. In 2022 the black hole at the centre of the Milky Way, Sagittarius A*, was imaged too.
December 2020
mRNA vaccines · Medicine
mRNA vaccines give the body a genetic message containing the recipe for a virus protein; cells produce the protein and the immune system prepares against it. Karikó and Weissman's 2005 finding allowed mRNA to be used without triggering unwanted immune reactions. COVID-19 vaccines developed this way were authorised in December 2020. The work received the 2023 Nobel Prize in Physiology or Medicine.
2021
Views on the origin of living things in Islamic thought · Biology
There is no single view on the origin of living things in the Muslim world. Some authors see precursors of evolutionary ideas in the works of al-Jāḥiẓ and Ibn Khaldūn; others argue this projects modern concepts onto the past. Today views range from creationism, holding that species were created separately, through a view that exempts only Adam and Eve, to theistic evolution without exceptions.
July 2021
AlphaFold and protein structure prediction · Computing and artificial intelligence
Predicting a protein's three-dimensional shape from its amino-acid sequence was a 50-year-old problem in biology. AlphaFold 2 made predictions close to experimental accuracy at the CASP competition in 2020. Hassabis, Jumper and David Baker received the 2024 Nobel Prize in Chemistry. The predictions remain models that need experimental confirmation.
August 2021
Present-day global warming and its causes · Earth sciences
According to the World Meteorological Organization, 2025 was about 1.43 °C warmer than pre-industrial times, and the 11 years 2015–2025 are the warmest on record. The UN's climate panel, the IPCC, stated in 2021 that it is "unequivocal" that this warming is caused by human activities. Some scientists argue that the role of natural factors such as the Sun and cosmic rays is underestimated, or that the climate's sensitivity to CO₂ is exaggerated.
December 25, 2021
The James Webb Space Telescope · Space exploration
Launched on 25 December 2021, the James Webb Space Telescope observes in infrared light and can see the universe's first galaxies. In May 2025 the galaxy MoM-z14 was found, seen only about 280 million years after the Big Bang, the most distant galaxy known. The telescope also studies exoplanet atmospheres.
March 2022
The complete human genome · Biology
The Human Genome Project was declared "complete" in 2003, but about 8% of the genome could not be read for technical reasons. In 2022 the Telomere-to-Telomere (T2T) Consortium published the first gapless human genome using long-read sequencing. In 2023 a draft "pangenome" including genomes of 47 people of diverse ancestry was also published.
December 5, 2022
Fusion energy and ignition · Energy
The Sun's energy comes from the joining of light nuclei (fusion). On 5 December 2022 the US National Ignition Facility (NIF) reached "ignition" for the first time, getting more fusion energy out than the laser energy delivered to the fuel. In April 2025 this ratio exceeded four. However, the total electricity drawn by the lasers is still far larger, and there is no commercial fusion power plant yet.
January 18, 2024
The first Turkish astronaut · Space exploration
On 18 January 2024 Alper Gezeravcı became the first Turkish astronaut, travelling to the International Space Station on the Axiom-3 mission. He spent about two weeks on the station and carried out 13 scientific experiments prepared by Turkish institutions led by TÜBİTAK. The mission is the first step in the Turkish Space Agency's human spaceflight programme.
May 2024
Proof of the geometric Langlands conjecture · Mathematics
The Langlands programme aims to build a deep "dictionary" between number theory, geometry and symmetry, and is often called a "grand unified theory" of mathematics. In 2024 nine mathematicians announced a proof of its geometric form in a series of five papers of nearly 1,000 pages.
July 2024
The fifth Busy Beaver number BB(5) · Mathematics
The "Busy Beaver" question asks how many steps a Turing machine with a given number of states can take before halting. For five states the answer was unknown for 60 years. In 2024 an online volunteer collaboration showed the answer is 47,176,870 and published a computer-verified proof.
December 2024
Quantum computers · Computing and artificial intelligence
Quantum computers use "qubits" with superposition and entanglement instead of bits. It has been shown theoretically that they could solve some problems, such as factoring large numbers, much faster than classical computers. Qubits are very error-prone; Google's Willow processor in 2024 was the first experiment to show error rates falling as the number of qubits grows. A useful, large-scale quantum computer does not yet exist.
February 2025
Proof of the Kakeya conjecture in three dimensions · Mathematics
Sets that contain a unit line segment in every direction (Kakeya sets) can have zero volume. Even so, the conjecture says they are as large, in "dimension", as the space they live in. Hong Wang and Joshua Zahl posted a proof of the three-dimensional case to arXiv in February 2025.
April 2025
The claimed biosignature on K2-18 b · Astronomy and cosmology
In April 2025 a team announced, based on JWST data, "the strongest hints yet" of dimethyl sulfide (DMS), a gas known on Earth to be produced only by living things, in the atmosphere of the planet K2-18 b. Reanalyses by other teams concluded that the data are not strong enough to show that the gas is present.
May 2025
Personalised in vivo gene-editing therapy · Medicine
In 2025 in the US, a baby named KJ, born with a severe rare metabolic disease (CPS1 deficiency), received a base-editing therapy designed and manufactured in six months solely to correct his mutation. The results were published in the New England Journal of Medicine. The long-term effect and safety of this single-patient result are not yet known.
June 2025
The muon magnetic moment (g−2), final measurement · Physics
The muon's magnetic property is a very sensitive test of the Standard Model. For years the experimental value and the theoretical prediction seemed to disagree, which was discussed as a sign of "new physics". Fermilab's final result in June 2025 reached a precision of 127 parts per billion. Its gap with the theoretical prediction, updated at the same time, largely closed.
July 2025
AI reaching gold-medal level at the International Mathematical Olympiad · Computing and artificial intelligence
In July 2025 Google DeepMind's Gemini Deep Think model solved five of the six International Mathematical Olympiad problems with natural-language proofs and was graded by official coordinators at gold-medal level (35 of 42). OpenAI reported the same score in its own evaluation. The models did not solve the sixth problem, regarded as the hardest.
September 10, 2025
A potential biosignature on Mars (Cheyava Falls) · Space exploration
In 2024 NASA's Perseverance rover found a rock with "leopard spots" in an ancient river valley in Jezero Crater. A paper published in Nature in September 2025 reported that iron phosphate and sulphide minerals found with organic carbon are commonly associated with microbial activity on Earth. The authors called this a "potential biosignature" and noted that the same features could also form by non-living chemical processes. A definitive answer requires returning the sample to Earth.
October 2025
Metal–organic frameworks (Nobel 2025) · Chemistry
Metal–organic frameworks (MOFs) are crystals built from metal ions linked by organic molecules, with very large empty volumes inside. The internal surface area of one gram of MOF can approach that of a football pitch. They are being developed for uses such as harvesting water and carbon dioxide from the air. They were the subject of the 2025 Nobel Prize in Chemistry.
October 2025
Regulatory T cells and immune tolerance (Nobel 2025) · Medicine
Why does the immune system attack microbes but not our own tissues? In 1995 Sakaguchi identified a special group of T cells that brake immune responses (regulatory T cells). In 2001 Brunkow and Ramsdell found FOXP3, the gene that controls their development. These discoveries received the 2025 Nobel Prize in Physiology or Medicine. Treatments for autoimmune disease and cancer are being developed on this basis.
April 1, 2026
Artemis II, humans around the Moon after 50 years · Space exploration
Launched on 1 April 2026, Artemis II was the first crewed mission to the Moon since 1972. Four astronauts in the Orion capsule flew around the far side of the Moon and took from Apollo 13 the record for the farthest humans have travelled from Earth. The crew splashed down in the Pacific on 10 April. The Artemis programme aims to land near the Moon's south pole on later missions.

Without a certain date

The dates of the following are disputed; each page lists the different views.

Aḥmad Yasawī and the Dīwān-i Ḥikmat — Traditional view · Scholars' caution
Buddhism — Theravāda tradition · Modern historiography
Cave art and the first symbols — Archaeology (Sulawesi, Indonesia) · Archaeology (Spain; Neanderthal claim)
Control of fire — Archaeology (Wonderwerk, South Africa) · Archaeology (Gesher Benot Ya'aqov, Israel) · Archaeology (critical view based on European data) · Greek mythology
Counting and the Ishango bone — Archaeology (Ishango, Democratic Republic of the Congo)
Daoism and the Daodejing — Traditional account (Sima Qian) · Textual history and the Guodian finds
Farming and Göbekli Tepe — Archaeology (Fertile Crescent) · Archaeology (Göbekli Tepe) · Judaism and Christianity (Genesis)
Humanity — Palaeoanthropology (fossil dating) · Palaeoanthropology (East Africa) · Population genetics · Islam (Qur'an) · Judaism and Christianity (Genesis) · Hinduism (Puranas)
Rābiʿa al-ʿAdawiyya and divine love — Commonly accepted date · Earlier date in some sources
Stone tools — Archaeology (Lomekwi 3, Kenya) · Archaeology (Gona, Ethiopia; Oldowan)
The age of the Earth — Radiometric dating (current geology) · Lord Kelvin (1862, cooling calculation) · Young-earth creationism (literal reading of Genesis) · Islam (Qur'an)
The first origin of life (abiogenesis) — Geology (Isua, Greenland; disputed) · Islam (Qur'an) · Judaism and Christianity (Genesis)
The homeland of the Indo-European languages — Steppe (Kurgan) hypothesis · Anatolian hypothesis · South Caucasus / West Asia view
The invention of writing — Archaeology (Mesopotamia, Uruk) · Archaeology (Egypt, Abydos U-j) · Islamic tradition (exegesis and stories of the prophets)
The origin of language — Gradual, early emergence view · Late, abrupt emergence view · Islam (Qur'an) · Judaism and Christianity (Genesis)
The wheel and wheeled vehicles — Radiocarbon dates and depictions
Yunus Emre — Date given in the Risālat al-Nuṣḥiyya itself · Traditional records of his death
Zoroastrianism and the Avesta — Early dating based on linguistic comparison · Traditional Zoroastrian chronology ("258 years before Alexander") · Range proposed by scholars