Static universe
A cosmological model in which the universe’s overall scale does not change with time. Einstein’s 1917 model is a prominent example.
Einstein field equations: Equations relating spacetime geometry to the distribution of matter and energy. Einstein used these equations to test whether a matter-filled universe could remain unchanging.
Albert Einstein: The physicist who developed general relativity and introduced a static cosmological model in 1917. He modified his gravitational equations to permit a matter-filled, unchanging cosmos.
Expanding universe: A cosmological model in which the average distance between unbound galaxies increases over time. It matches the observed large-scale recession of galaxies, unlike a static model.
Age of the universe: The time elapsed since the universe entered its early hot, dense phase, estimated at about 13.8 billion years. A truly eternal static cosmos avoids the finite cosmic age inferred from expansion.
Cosmological constant: A constant term in Einstein’s field equations that contributes uniform energy density and pressure to spacetime. Einstein introduced it to balance gravity in his static cosmological model.
World's premier observatory: An astronomical observatory in California that housed the 100-inch Hooker Telescope. Observations made there helped reveal that distant galaxies lie beyond the Milky Way.
Big Bang: The cosmological model that describes the universe’s evolution from an early hot, dense state. Its expanding history replaces the eternal unchanging cosmos of static models.
Olbers' paradox: The question of why the night sky is dark if an infinite, eternal, uniform universe contains stars everywhere. Its classical assumptions include an eternal, static universe, which makes the darkness puzzling.
Einstein static universe: Einstein’s 1917 cosmological solution, with positive spatial curvature, matter, and a cosmological constant. It is the best-known specific realization of a static universe.
Edwin Hubble: The American astronomer whose observations established the extragalactic nature of spiral nebulae and linked distance with recession speed. His findings helped displace the idea of a permanently static cosmos.