Einstein's static universe, aka the Einstein universe or the Einstein static eternal universe, is a relativistic model of the universe proposed by

Albert Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...

in 1917. Shortly after completing the

general theory of relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the differential geometry, geometric scientific theory, theory of gravitation published by Albert Einstein in 1915 and is the current descr ...

, Einstein applied his new theory of gravity to the universe as a whole. Assuming a universe that was static in time, and possessed of a uniform distribution of matter on the largest scales, Einstein was led to a finite, static universe of

spherical A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the ce ...

spatial curvature. To achieve a consistent solution to the

Einstein field equations In the general theory of relativity, the Einstein field equations (EFE; also known as Einstein's equations) relate the geometry of spacetime to the distribution of matter within it. The equations were published by Einstein in 1915 in the form ...

for the case of a static universe with a non-zero density of matter, Einstein found it necessary to introduce a new term to the field equations, the

cosmological constant In cosmology, the cosmological constant (usually denoted by the Greek capital letter lambda: ), alternatively called Einstein's cosmological constant, is the constant coefficient of a term that Albert Einstein temporarily added to his field eq ...

. In the resulting model, the radius ''R'' and density of matter ''ρ'' of the universe were related to the cosmological constant Λ according to Λ = 1/''R''² = ''κρ''/2, where ''κ'' is the

Einstein gravitational constant In the general theory of relativity, the Einstein field equations (EFE; also known as Einstein's equations) relate the geometry of spacetime to the distribution of matter within it. The equations were published by Einstein in 1915 in the form ...

. Following the discovery by Edwin Hubble of a linear relation between the redshifts of the galaxies and their distance in 1929, Einstein abandoned his static model of the universe and proposed expanding models such as the Friedmann–Einstein universe and the

Einstein–de Sitter universe The Einstein–de Sitter universe is a model of the universe proposed by Albert Einstein and Willem de Sitter in 1932. On first learning of Edwin Hubble's discovery of a linear relation between the redshift of the galaxies and their distance, Eins ...

. In both cases, he set the cosmological constant to zero, declaring it "no longer necessary ... and theoretically unsatisfactory". In many Einstein biographies, it is claimed that Einstein referred to the cosmological constant in later years as his "biggest blunder". The astrophysicist

Mario Livio Mario Livio (born June 19, 1945) is an Israeli-American astrophysicist and an author of works that popularize science and mathematics. For 24 years (1991-2015) he was an astrophysicist at the Space Telescope Science Institute, which operates th ...

has recently cast doubt on this claim, suggesting that it may be exaggerated.

References

General relativity Albert Einstein {{relativity-stub