Hundred Years of Einstein's Cosmological Constant

It was little over a hundred years ago that Einstein introduced the ‘cosmological constant’ in his General Theory of Relativity in order to obtain a static universe, to conform to the philosophical view of the universe at that time. What Einstein subsequently dubbed as the ‘biggest blunder’ of his life (after Hubble’s discovery of the expanding universe) has come back in vogue in cosmology. Here we look at the evolution of the concept of the cosmological constant from its inception to it possibly making up close to about 70% of the energy density of the universe.