Cosmology

Name

Author and date

Classification

Remarks

Babylonian cosmology

Babylonian literature (1900-1200 B.C.)

Plurality of heavens and earths

The Earth and heavens are a "spatial whole, even one of round shape," revolving around the "cult-place of the deity" rather than the Earth,[6] and there is a plurality of heavens and earths.[7]

Brahmanda (Hindu Cosmology)

Hindu Rigveda (1500-1200 B.C.)

Cyclical or oscillating, Infinite in time

The universe sustains for around 311 trillion and 40 billion years that is 100 years of the cosmic creator Brahma. There is a smaller period of unmanifestation in around 4 billion years that is one day in the life of Brahma. The universe cycles between expansion and total collapse. After one cycle of the life of Brahma another universe follows up to an infinite number each of which exists for a time period of 311 trillion and 40 billion years. It also speaks of an infinite number of universes at one given point of time. Universe 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[disambiguation needed] 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.

Pythagorean Universe

Philolaus (d. 390 BC)

Existence of a "Central Fire" at the center of the Universe.

At the center of the Universe is a central fire, around which the Earth, Sun, Moon and Planets revolve uniformly. The sun revolves around the central fire once a year, the stars are immobile. The earth in its motion maintains the same hidden face towards the central fire, hence it is never seen. This is the first known non-geocentric model of the Universe.[8]

Stoic universe

Stoics (300 B.C. - 200 A.D.)

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)

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.

Multiversal cosmology

Fakhr al-Din al-Razi (1149–1209)

Multiverse, multiple worlds & universes

Al-Razi rejects the 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," [9] and that there could be an infinite number of universes.[10]

Maragha models

Maragha school (1259–1528)

Geocentric

Various modifications to Ptolemaic model and Aristotelian universe, including rejection of equant and eccentrics at Maragheh observatory, and introduction of Tusi-couple by Al-Tusi. Alternative models later proposed, including the first accurate lunar model by Ibn al-Shatir, a model rejecting stationery Earth in favour of Earth's rotation by Ali Ku?çu, and planetary model incorporating "circular inertia" by Al-Birjandi.

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 ?. In effect ? is equivalent to a repulsive force which counteracts gravity. Unstable.

De Sitter universe

Willem de Sitter 1917

Expanding flat space.

Steady state. ? > 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 ?

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 ?

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 ; ? = 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

? > 0 ? > |Gravity|

? is positive and has a magnitude greater than Gravity. Universe has initial high density state (‘primeval atom’). Followed by a two stage expansion. ? 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. ? 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."[citation needed]

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

Cyclic model

Lauris Baum;Paul Frampton 2007

Solution of Tolman's entropy problem

Phantom dark energy fragments universe

into large number of disconnected patches. Our patch contracts containing only dark energy with zero entropy.