In 1917, just one year after the publication of his general theory of relativity, German American physicist Albert Einstein wrote a short paper titled Cosmological Considerations on the General Theory of Relativity. For the first time the universe was treated as a four-dimensional (three spatial and one temporal) manifold termed space-time. The geometry of the model universe was determined by solving the Einstein field equations, which relate the curvature of space-time to matter distribution. Modern cosmology was born. And so was the physics of the vacuum.

Einstein initially argued for a static universe and a dozen years would pass before Milton Humason and American astronomer Edwin Hubble would discover the universal expansion of the cosmos. Although Einstein's own field equations dictated that the universe could not be static, Einstein attempted to reconcile general relativity with a static universe by adding a new term to his...