List of estimates of the age of the universe

Since the concept of an expanding universe was first introduced, there have been many estimates of the age of the universe that have evolved with scientific discoveries and developments. Many early estimates used the recessional velocities of distant galaxies to calculate the age of the universe, often getting results of about 2 Gyr (2 billion years) or less. Because this was less than calculations of Earth's age at the time, which were considered more accurate, doubt was cast upon the theory of expansion. This problem was resolved in 1952 when Walter Baade discovered that distances to neighboring galaxies, which were being used in the calculation of the age of the universe, were larger than previously thought; this brought the estimated age of the universe to about 4 Gyr.

As time went on and observations improved, estimates for the age of the universe rose, with most estimates in the 1970s through 1990s in the range of 8–20 Gyr. Many of the higher estimates were due to the age of the oldest globular clusters, which had been estimated to be as high as 16 Gyr; these ages were later revised lower after new data revealed that they were further than previously thought.

The launch of the Wilkinson Microwave Anisotropy Probe (WMAP) in 2001 and the Planck spacecraft in 2009, both measuring anisotropies in the cosmic microwave background, allowed astronomers to make more precise measurements of the age of the universe. The first year of WMAP data resulted in an estimated age of Gyr by two independent research groups. , the accepted age of the universe is Gyr, based on data from the Planck spacecraft analyzed in 2018.

List +EstimateYearMethodAuthorsReferences10 Gyr1922Mathematical derivation of the Friedmann equationsAlexander Friedmann1.8 Gyr1929Recessional velocity, Cepheid variablesEdwin Hubble>2 Gyr1930Gravitational collapse of nebulaeJames Jeans<2 Gyr1931Mathematical derivation from relativityArthur Eddington1–10 Gyr1935Recessional velocityEdwin Hubble, Richard Tolman5–10 Gyr1936Orbits of binary starsJames Jeans0.75–1.5 Gyr1937Recessional velocity, positive cosmological constantEdwin Hubble0.7 Gyr1938Recessional velocityPaul Dirac<1 Gyr1942Recessional velocityEdwin Hubble3.64 Gyr1949Recessional velocity, nonhomogenous cosmologyGuy Omer3.5 Gyr1952Revised distance calculations, recessional velocityWalter Baade4.1 Gyr1956Dirac large numbers hypothesisC. Gilbert Gyr1958Redshift–magnitude relationAllan Sandage17.7 Gyr1972Cepheid variablesAllan Sandage8–18 Gyr1974Oldest globular clustersIcko Iben Jr.13-20 Gyr1974Deuterium-limited density, oldest globular clusters, nucleochronology, galactic evolutionJ. Richard Gott, James Gunn, David Schramm, Beatrice Tinsley6–20 Gyr1977Nucleochronology, galactic evolutionKem Hainebach, David Schramm13.5–15.5 Gyr1978Oldest globular clusters, nuclear chronologyDemosthenes Kazanas, David Schramm, Kem Hainebach Gyr1980–1981Nuclear chronologyWilliam Alfred Fowler, David Schramm, Sidney van den Bergh Gyr1987White dwarf luminosity distributionDon Winget et al.13–18 Gyr1992Nucleochronology, oldest globular clustersSidney van den Bergh>16 Gyr1992RR Lyrae stars, oldest globular clustersYoung-Wook Lee>13 Gyr1994Cosmic microwave background anisotropiesMarc Kamionkowski, David Spergel, Naoshi Sugiyama≥12.07 Gyr1996Oldest globular clustersBrian Chaboyer, Pierre Demarque, Peter Kernan, Lawrence Krauss9.7–15 Gyr1998Oldest globular clustersLawrence Krauss≥9.5 Gyr1998Oldest globular clustersBrian Chaboyer Gyr1999Literature reviewCharles Lineweaver< Gyr2000Literature reviewWendy Freedman Gyr2001Cosmic microwave background anisotropiesLloyd Knox, Nelson Christensen, Constantinos Skordis Gyr2001Cluster ellipticals, cosmic microwave background, type Ia supernovaeIgnacio Ferreras, Alessandro Melchiorri, Joseph Silk Gyr2003Wilkinson Microwave Anisotropy Probe dataDavid Spergel et al. Gyr2003Wilkinson Microwave Anisotropy Probe dataCharles Bennett et al. Gyr2007Wilkinson Microwave Anisotropy Probe dataDavid Spergel et al. Gyr2008Data from Wilkinson Microwave Anisotropy Probe, Sloan Digital Sky Survey, Hubble Space TelescopeFrancesco De Bernardis, Alessandro Melchiorri, Licia Verde, Raul Jimenez Gyr2008Data from Wilkinson Microwave Anisotropy Probe, Sloan Digital Sky Survey, Hubble Space Telescope, high-resolution CMB experiments, two degree field galaxy redshift survey, type 1a supernovaeFrancesco De Bernardis, Alessandro Melchori, Licia Verde, Raul Jimenez Gyr2013Wilkinson Microwave Anisotropy Probe dataCharles Bennett et al. Gyr2014Planck data, WMAP polarization low-multipole likelihoodPlanck collaboration Gyr2014Planck data, WMAP polarization low-multipole likelihood, high-resolution CMB experiments, baryon acoustic oscillationPlanck collaboration Gyr2016Planck dataPlanck collaboration Gyr2020Planck dataPlanck collaboration

See also Age of the universe List of measurements of the Hubble constant Cosmic age problem Lambda-CDM model FLRW metric BOOMERanG experiment

References