Einstein's assumption that the universe is static was in conflict with his own field equations

The cosmological principle continuous to play an important role in cosmological modelling to this day. However, Einstein’s second assumption that the universe is static was in conflict with his field equations, which permitted models of the universe that were homogeneous and isotropic, but not static. In this regard, Einstein’s difficulties were essentially the same that Newton had faced: A static Newtonian model involving an infinite container with an infinite number of stars was unstable