The disproved theory I will be writing about is the Einstein Static or Stationary Universe. Albert Einstein came up with the theory in the year 1917, just after completing the theory of relativity. This theory is about a relativistic model of the universe in which the universe is both spatially and temporally infinite and space is neither expanding nor contracting. This model of the universe became known as the Einstein World or Einstein’s static universe.
People believed in Einstein static universe for 14 years until the year 1931. In his seminal Cosmological Considerations paper of 1917, Einstein showed that general relativity could indeed give a consistent model of the static universe. However, two assumptions were necessary. Firstly, the universe was of closed spatial geometry like a sphere and had no beginning or end. Secondly, a consistent solution necessitated the introduction of a new term to the field equations of relativity. Some regarded the new term, known as the cosmological constant, as something of a fudge factor and claimed that it marred the symmetry and simplicity of the original field equations. However, general relativity certainly allowed the term; indeed, it is a little-known fact that Einstein had noted the possibility of such an extension to the field equations in his original exposition of 1916. Now the cosmological constant found an important application because it allowed a model of the universe that was consistent with Einstein’s views on the relativity of inertia.
Einstein’s Cosmological Considerations paper is a fascinating read as it contains a discussion of his views of the limitations of Newtonian cosmology and a description of his long path to a satisfactory relativistic model of the universe.