Einstein’s Static UniverseEinstein’s Static Universe

(1917)(1917)

De Sitter’s Accelerating UniverseDe Sitter’s Accelerating Universe

Always expandingAlways expandingexponential curve R = exp[texponential curve R = exp[t/3]/3]

No matter – only No matter – only It has no beginning and no endIt has no beginning and no end

(1917)(1917)Willem De SitterWillem De Sitter

1872-19341872-1934

Friedmann’s universesFriedmann’s universes

1922,19241888-1925

Edwin HubbleEdwin Hubble(1889-1953)

Hubble-Humason Law todayHubble-Humason Law today

Milton HumasonMilton Humason(1891-1972)

The Einstein-de Sitter UniverseThe Einstein-de Sitter Universe

‘‘I do not think the paper very important I do not think the paper very important myself, but de Sitter was keen on it’myself, but de Sitter was keen on it’ EinsteinEinstein

‘‘the paper by Einstein and myself I do the paper by Einstein and myself I do not myself consider the result of muchnot myself consider the result of muchimportance, but Einstein seemed to thinkimportance, but Einstein seemed to thinkIt was’It was’ De SitterDe Sitter

1932

= 0= 0

Lemaître's UniverseLemaître's Universe

The best description of The best description of the visible universethe visible universe todaytoday

1927

> 0> 0

Tolman’s Oscillating Tolman’s Oscillating UniverseUniverse

Richard Tolman and Einstein at Cal Tech

1932

Tolman includes theTolman includes the22ndnd Law of thermodynamics: Law of thermodynamics:

Oscillations growOscillations grow(1932)(1932)

JDB + Dabrowski include theJDB + Dabrowski include thecosmological constant:cosmological constant:Oscillations always end Oscillations always end

(1995)(1995)

Kasner’s Anisotropic UniverseKasner’s Anisotropic Universe

Edward KasnerEdward Kasner(1878-1955)(1878-1955)

19211921

Volume abc time

expansionexpansion shearshear rotationrotation

Gödel's Rotating UniverseGödel's Rotating Universe

Allows time travelAllows time travelto occur !to occur !

1949

Real Universes Tend to Get LumpyReal Universes Tend to Get Lumpy

Is this the origin of Is this the origin of galaxies ?galaxies ?

Newton 1693Newton 1693Jeans 1902Jeans 1902

Lifshitz 1946Lifshitz 1946

The Big Bang UniversesThe Big Bang Universes

The Evidence of a Hot Early HistoryThe Evidence of a Hot Early History

A temporary lambdaA temporary lambda

The Inflationary UniverseThe Inflationary Universe

1981

Even Smaller BeginningsEven Smaller Beginnings

Chaotic InflationChaotic Inflation

Geography is more complicated than we thoughtGeography is more complicated than we thought

Eternal InflationEternal Inflation

More than 10More than 1010107777

by-universes from our patch aloneby-universes from our patch alone

Lemaître's universe describes our visible universe to high precisionLemaître's universe describes our visible universe to high precision

The Universe is Accelerating AgainThe Universe is Accelerating Again

> 0

The Return of Lambda ?The Return of Lambda ?

?