Also in that decade, Albert Einstein 's theory of general relativity was found to admit no static cosmological solutions, given the basic assumptions of cosmology described in the Big Bang's theoretical underpinnings. The universe (i.e., the space-time metric) was described by a metric tensor that was either expanding or shrinking (i.e., was not constant or invariant). This result, coming from an evaluation of the field equations of the general theory, at first led Einstein himself to consider that his formulation of the field equations of the general theory may be in error, and he tried to correct it by adding a cosmological constant. This constant would restore to the general theory's description of space-time an invariant metric tensor for the fabric of space/existence. The first person to seriously apply general relativity to cosmology without the stabilizing cosmological constant was Alexander Friedmann. Friedmann derived the expanding-universe solution to general relativity field equations in 1922. Friedmann's 1924 papers included " Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes " (About the possibility of a world with constant negative curvature) which was published by the Berlin Academy of Sciences on 7 January 1924. Friedmann's equations describe the Friedmann–Lemaitre–Robertson–Walker universe.