Timeline of cosmological theories

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This timeline of cosmological theories and discoveries is a chronological record of the development of humanity's understanding of the cosmos over the last two-plus millennia. Modern cosmological ideas follow the development of the scientific discipline of physical cosmology.


  • c. 16th century BCE – Mesopotamian cosmology has a flat, circular Earth enclosed in a cosmic ocean.[1]
  • c. 12th century BCE – The Rigveda has some cosmological hymns, particularly in the late book 10, notably the Nasadiya Sukta which describes the origin of the universe, originating from the monistic Hiranyagarbha or "Golden Egg".
  • 6th century BCE – The Babylonian world map shows the Earth surrounded by the cosmic ocean, with seven islands arranged around it so as to form a seven-pointed star. Contemporary Biblical cosmology reflects the same view of a flat, circular Earth swimming on water and overarched by the solid vault of the firmament to which are fastened the stars.
  • 6th–4th century BCE – Greek philosophers, as early as Anaximander,[2] introduce the idea of multiple or even infinite universes.[3] Democritus further detailed that these worlds varied in distance, size; the presence, number and size of their suns &/ moons; and that they are subject to destructive collisions.[4] Also during this time period, the Greeks established that the earth is spherical rather than flat.[5][6]
  • 4th century BCE – Aristotle proposes an Earth-centered universe in which the Earth is stationary and the cosmos (or universe) is finite in extent but infinite in time. However, others like Philolaus and Hicetas rejected geocentrism.[7] Plato seems to have argued that the universe did have a beginning, but Aristotle and others interpreted his words differently.[8]
  • 4th century BCE – De Mundo – Five elements, situated in spheres in five regions, the less being in each case surrounded by the greater – namely, earth surrounded by water, water by air, air by fire, and fire by ether – make up the whole Universe.[9]
  • 3rd century BCE – Aristarchus of Samos proposes a Sun-centered universe
  • 3rd century BCE – Archimedes in his essay The Sand Reckoner, estimates the diameter of the cosmos to be the equivalent in stadia of what we call two light years
  • 2nd century BCE – Seleucus of Seleucia elaborates on Aristarchus' heliocentric universe, using the phenomenon of tides to explain heliocentrism
  • 2nd century CE – Ptolemy proposes an Earth-centered universe, with the Sun, Moon, and visible planets revolving around the Earth
  • 5th century (or earlier) – Ancient Buddhist texts speak of "hundreds of thousands of billions, countlessly, innumerably, boundlessly, incomparably, incalculably, unspeakably, inconceivably, immeasurably, inexplicably many worlds" to the east, and "infinite worlds in the ten directions".[10][11]
  • 5th–11th centuries – Several astronomers propose a Sun-centered universe, including Aryabhata, Albumasar[12] and Al-Sijzi
  • 6th century – John Philoponus proposes a universe that is finite in time and argues against the ancient Greek notion of an infinite universe
  • 7th century – The Qur'an says in Chapter 21: Verse 30 – "Have those who disbelieved not considered that the heavens and the earth were a joined entity, and We separated them ... "
  • c. 8th century – Puranic Hindu cosmology, in which the Universe goes through repeated cycles of creation, destruction and rebirth, with each cycle lasting 4.32 billion years. In each cycle, the universe expands from a single point or speck of dust, until it collapses.[13] The texts also speak of innumerable worlds or universes.[14]
  • 9th–12th centuries – Al-Kindi (Alkindus), Saadia Gaon (Saadia ben Joseph) and Al-Ghazali (Algazel) support a universe that has a finite past and develop two logical arguments against the notion of an infinite past, one of which is later adopted by Immanuel Kant
  • 964 – Abd al-Rahman al-Sufi (Azophi), a Persian astronomer, makes the first recorded observations of the Andromeda Galaxy and the Large Magellanic Cloud, the first galaxies other than the Milky Way to be observed from Earth, in his Book of Fixed Stars
  • 12th century – Fakhr al-Din al-Razi discusses Islamic cosmology, rejects Aristotle's idea of an Earth-centered universe, and, in the context of his commentary on the Qur'anic verse, "All praise belongs to God, Lord of the Worlds," proposes that the universe has more than "a thousand thousand worlds beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has."[15] He argued that there exists an infinite outer space beyond the known world,[16] and that there could be an infinite number of universes.[17]
  • 13th century – Nasīr al-Dīn al-Tūsī provides the first empirical evidence for the Earth's rotation on its axis
  • 15th century – Ali Qushji provides empirical evidence for the Earth's rotation on its axis and rejects the stationary Earth theories of Aristotle and Ptolemy
  • 15th–16th centuries – Nilakantha Somayaji and Tycho Brahe propose a universe in which the planets orbit the Sun and the Sun orbits the Earth, known as the Tychonic system
  • 1543 – Nicolaus Copernicus publishes his heliocentric universe in his De revolutionibus orbium coelestium
  • 1576 – Thomas Digges modifies the Copernican system by removing its outer edge and replacing the edge with a star-filled unbounded space
  • 1584 – Giordano Bruno proposes a non-hierarchical cosmology, wherein the Copernican Solar System is not the center of the universe, but rather, a relatively insignificant star system, amongst an infinite multitude of others
  • 1610 – Johannes Kepler uses the dark night sky to argue for a finite universe
  • 1687 – Sir Isaac Newton's laws describe large-scale motion throughout the universe
  • 1720 – Edmund Halley puts forth an early form of Olbers' paradox
  • 1729 – James Bradley discovers the aberration of light, due to the Earth's motion around the Sun.
  • 1744 – Jean-Philippe de Cheseaux puts forth an early form of Olbers' paradox
  • 1755 – Immanuel Kant asserts that the nebulae are really galaxies separate from, independent of, and outside the Milky Way Galaxy; he calls them island universes.
  • 1785 – William Herschel proposes the theory that our Sun is at or near the center of the galaxy.
  • 1791 – Erasmus Darwin pens the first description of a cyclical expanding and contracting universe in his poem The Economy of Vegetation
  • 1826 – Heinrich Wilhelm Olbers puts forth Olbers' paradox
  • 1837 – Following over 100 years of unsuccessful attempts, Friedrich Bessel, Thomas Henderson and Otto Struve measure the parallax of a few nearby stars; this is the first measurement of any distances outside the Solar System.
  • 1848 – Edgar Allan Poe offers first correct solution to Olbers' paradox in Eureka: A Prose Poem, an essay that also suggests the expansion and collapse of the universe
  • 1860s – William Huggins develops astronomical spectroscopy; he shows that the Orion nebula is mostly made of gas, while the Andromeda nebula (later called Andromeda Galaxy) is probably dominated by stars.



Since 2000[edit]

See also[edit]

Physical cosmology[edit]

Belief systems[edit]



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