The following table outlines the significant historical cosmologies in chronological order.
Historical descriptions of the cosmos
| NAME | Author & Date | Classification | REMARKS |
|---|---|---|---|
| Brahmanda | Hindu Rigveda (1500-1200 B.C.) | Cyclical or oscillating, Infinite in time | The universe is a cosmic egg that cycles between expansion and total collapse. It expanded from a concentrated form —a point called a Bindu. The universe, as a living entity, is bound to the perpetual cycle of birth, death, and rebirth |
| Atomist universe | Anaxagoras (500-428 B.C.) & later Epicurus | Infinite in extent | The universe contains only two things: an infinite number of tiny seeds, or atoms, and the void of infinite extent. All atoms are made of the same substance, but differ in size and shape. Objects are formed from atom aggregations and decay back into atoms. Incorporates Leucippus’ principle of causality: ”nothing happens at random; everything happens out of reason and necessity.” The universe was not ruled by gods. |
| Stoic universe | Stoics (400-200 B.C.) | Island universe | The cosmos is finite and surrounded by an infinite void. It is in a state of flux, as it pulsates in size and periodically passes through upheavals and conflagrations. |
| Aristotelian universe | Aristotle (384-322 B.C.) | Geocentric, static, steady state, finite extent, infinite time | Spherical earth is surrounded by concentric celestial spheres. Universe exists unchanged throughout eternity. Contains a 5th element called aether (later known as quintessence). |
| Aristarchean universe | Aristarchus (circa 280 B.C.) | Heliocentric | Earth rotates daily on its axis and revolves annually about the sun in a circular orbit. Sphere of fixed stars is centered about the sun. |
| Seleucian universe | Seleucus of Seleucia (circa 190 B.C.) | Heliocentric | Modifications to the Aristarchean universe, with the inclusion of the tide phenomenon to explain heliocentrism. |
| Ptolemaic model (based on Aristotelian universe) | Ptolemy (2nd century A.D.) | Geocentric | Universe orbits about a stationary Earth. Planets move in circular epicycles, each having a center that moved in a larger circular orbit (called an eccentric or a deferent) around a center-point near the Earth. The use of equants added another level of complexity and allowed astronomers to predict the positions of the planets. The most successful universe model of all time, using the criterion of longevity. Almagest (the Great System). |
| Aryabhatan model | Aryabhata (499 A.D.) | Geocentric or Heliocentric | The Earth rotates and the planets move in elliptical orbits, possibly around either the Earth or the Sun. It is uncertain whether the model is geocentric or heliocentric due to planetary orbits given with respect to both the Earth and the Sun. |
| Abrahamic universe | Medieval philosophers (500-1200) | Finite in time | The universe that is finite in time and has a beginning is proposed by the Christian philosopher, John Philoponus, who argues against the ancient Greek notion of an infinite past. Logical arguments supporting a finite universe are developed by the early Muslim philosopher, Alkindus; the Jewish philosopher, Saadia Gaon; and the Muslim theologian, Algazel. |
| Albumasar model | Ja'far ibn Muhammad Abu Ma'shar al-Balkhi (787-886) | Heliocentric | His planetary orbits are only given with respect to the Sun rather than the Earth, thus suggesting a heliocentric model. |
| Maragha models | Maragha school (1259-1474) | Geocentric | Various modifications to the Ptolemaic model and Aristotelian universe, such as the rejection of the equant and eccentrics at the Maragheh observatory, the first accurate lunar model by Ibn al-Shatir, and the rejection of a stationery Earth in favour of the Earth's rotation by Ali Kuşçu. |
| Nilakanthan model | Nilakantha Somayaji (1444-1544) | Geocentric and Heliocentric | A universe in which the planets orbit the Sun and the Sun orbits the Earth, similar to the later Tychonic system. |
| Copernican universe | Nicolaus Copernicus (1543) | Heliocentric | The geocentric Maragha model of Ibn al-Shatir adapted to meet the requirements of the ancient heliocentric Aristarchean universe in his De revolutionibus orbium coelestium. |
| Tychonic system | Tycho Brahe (1546-1601) | Geocentric and Heliocentric | A universe in which the planets orbit the Sun and the Sun orbits the Earth, similar to the earlier Nilakanthan model. |
| Static Newtonian | Sir Isaac Newton (1642-1727) | Static (evolving), steady state, infinite | Every particle in the universe attracts every other particle. Matter on the large scale is uniformly distributed. Gravitationally balanced but UNSTABLE. |
| Cartesian Vortex universe | René Descartes 17th century | Static (evolving), steady state, infinite | A system of huge swirling whirlpools of aethereal or fine matter produces what we would call gravitational effects. His vacuum was not empty. All space was filled with matter that swirled around in large and small vortices. |
| Hierarchical universe | Immanuel Kant, Johann Lambert 1700s | Static (evolving), steady state, infinite | Matter is clustered on ever larger scales of hierarchy. Matter is endlessly being recycled. |
| Einstein Universe with a cosmological constant | Albert Einstein 1917 | Static (nominally). Bounded (finite) | “Matter without motion.” Contains uniformly distributed matter. Uniformly curved spherical space; based on Riemann’s hypersphere. Curvature is set equal to Λ. In effect Λ is equivalent to a repulsive force which counteracts gravity. UNSTABLE. |
| De Sitter universe | Willem de Sitter 1917 | Expanding flat space. Steady state. Λ > 0 | “Motion without matter.” Only apparently static. Based on Einstein’s General Relativity. Space expands with constant acceleration. Scale factor (radius of universe) increases exponentially, i.e. constant inflation. |
| MacMillan | William MacMillan 1920s | Static & steady state | New matter is created from radiation. Starlight is perpetually recycled into new matter particles. |
| Friedmann universe of spherical space | Alexander Friedmann 1922 | Spherical expanding space. k= +1 ; no Λ | Positive curvature. Curvature constant k = +1 Expands then recollapses. Spatially closed (finite). |
| Friedmann universe of hyperbolic space | Alexander Friedmann 1924 | Hyperbolic expanding space. k= -1 ; no Λ | Negative curvature. Said to be infinite (but ambiguous). Unbounded. Expands forever. |
| Dirac large numbers hypothesis | Paul Dirac 1930s | Expanding | Demands a large variation in G, which decreases with time. Gravity weakens as universe evolves. |
| Friedmann zero-curvature, aka the Einstein-DeSitter universe | Einstein & DeSitter 1932 | Expanding flat space. k= 0 ; Λ = 0 Critical density | Curvature constant k = 0. Said to be infinite (but ambiguous). ‘Unbounded cosmos of limited extent.’ Expands forever. ‘Simplest’ of all known universes. Named after but not considered by Friedmann. Has a deceleration term q =½ which means that its expansion rate slows down. |
| Georges Lemaître the original Big Bang. aka Friedmann-Lemaître Model | Georges Lemaître 1927-29 | Expansion Λ > 0 Λ > |Gravity| | Λ is positive and has a magnitude greater than Gravity. Universe has initial high density state (‘primeval atom’). Followed by a two stage expansion. Λ is used to destabilize the universe. (Lemaître is considered to be the father of the big bang model.) |
| Oscillating universe (aka Friedmann-Einstein; was latter’s 1st choice after rejecting his own 1917 model) | Favored by Friedmann 1920s | Expanding and contracting in cycles | Time is endless and beginningless; thus avoids the beginning-of-time paradox. Perpetual cycles of big bang followed by big crunch. |
| Eddington | Arthur Eddington 1930 | first Static then Expands | Static Einstein 1917 universe with its instability disturbed into expansion mode; with relentless matter dilution becomes a DeSitter universe. Λ dominates gravity. |
| Milne universe of kinematic relativity | Edward Milne, 1933, 1935; William H. McCrea, 1930s | Kinematic expansion with NO space expansion | Rejects general relativity and the expanding space paradigm. Gravity not included as initial assumption. Obeys cosmological principle & rules of special relativity. The Milne expanding universe consists of a finite spherical cloud of particles (or galaxies) that expands WITHIN flat space which is infinite and otherwise empty. It has a center and a cosmic edge (the surface of the particle cloud) which expands at light speed. His explanation of gravity was elaborate and unconvincing. For instance, his universe has an infinite number of particles, hence infinite mass, within a finite cosmic volume. |
| Friedmann-Lemaître-Robertson-Walker class of models | Howard Robertson, Arthur Walker, 1935 | Uniformly expanding | Class of universes that are homogenous and isotropic. Spacetime separates into uniformly curved space and cosmic time common to all comoving observers. The formulation system is now known as the FLRW or Robertson-Walker metrics of cosmic time and curved space. |
| Steady-state expanding (Bondi & Gold) | Herman Bondi, Thomas Gold 1948 | Expanding, steady state, infinite | Matter creation rate maintains constant density. Continuous creation out of nothing from nowhere. Exponential expansion. Deceleration term q = -1. |
| Steady-state expanding (Hoyle) | Fred Hoyle 1948 | Expanding, steady state; but unstable | Matter creation rate maintains constant density. But since matter creation rate must be exactly balanced with the space expansion rate the system is unstable. |
| Ambiplasma | Hannes Alfvén 1965 Oskar Klein | Cellular universe, expanding by means of matter-antimatter annihilation | Based on the concept of plasma cosmology. The universe is viewed as meta-galaxies divided by double layers —hence its bubble-like nature. Other universes are formed from other bubbles. Ongoing cosmic matter-antimatter annihilations keep the bubbles separated and moving apart preventing them from interacting. |
| Brans-Dicke | Carl H. Brans; Robert H. Dicke | Expanding | Based on Mach’s principle. G varies with time as universe expands. “But nobody is quite sure what Mach’s principle actually means.” |
| Cosmic inflation | Alan Guth 1980 | Big Bang with modification to solve horizon problem and flatness problem. | Based on the concept of hot inflation. The universe is viewed as a multiple quantum flux —hence its bubble-like nature. Other universes are formed from other bubbles. Ongoing cosmic expansion kept the bubbles separated and moving apart preventing them from interacting. |
| Eternal Inflation (a multiple universe model) | Andreï Linde 1983 | Big Bang with cosmic inflation | A multiverse, based on the concept of cold inflation, in which inflationary events occur at random each with independent initial conditions; some expand into bubble universes supposedly like our entire cosmos. Bubbles nucleate in a spacetime foam. |
| Cyclic model | Paul Steinhardt; Neil Turok 2002 | Expanding and contracting in cycles; M theory. | Two parallel orbifold planes or M-branes collide periodically in a higher dimensional space. With quintessence or dark energy |
Table Notes: the term “static” simply means not expanding and not contracting. Symbol G represents Newton’s gravitational constant; Λ (Lambda) is the cosmological constant.
