Cosmology in general predates the physics that we rely upon in the twenty-first century. Its history is intertwined with religion as an attempt to understand or explain the workings of the world. Science on the grandest scale has felt great impedence from religious dogma and pontificators, specificly, the relationship between Gallileo and the Catholic church. The entire history of cosmology is a subject too broad for a small project to contend with, so I want to explore the workings of just the Big Bang theory; its creation, evolution and adaptation to new data, and revision with inflationary theory.
After Isaac Newton revolutionized mechanics, the term 'cosmology' (or 'cosmogeny' at the time) refered only to the solar system and the immediate environs. Newton did a lot to dispell the geo-centric myths surrounding celestial motion, with his theory of universal gravitation. If planets moved on celestial spheres, instead of moving because of gravity, gravity must not be universal.
Before Einstein, before his revolutionary theory of general relativity of 1915, most astronomers believed that the universe consisted of only one galaxy, the Milky Way. Outside galaxies were certainly studied, but not understood as independant and very distant galaxies similar to our own.
Einstein did not apply his new gravitational field equations to cosmological models until 1917. Predecessors such as Mach and Gallileo grappled with the concepts of inertia inspired Einstein. Newton had attempted to formulate a cosmological model using his theory of gravity, and reasoned in 1692 that the universe could be considered an infinite volume container with an infinite number of stars. Newton was unable to define a gravitational force acting upon a particular body with these boundary conditions however. Newton realized that a universe with matter and only gravity acting upon the matter would result in a universe which would eventually collapse. Obviously the universe has not collapsed, which puzzled Newton.
Einstein was also puzzled by the appropriate boundary conditions to apply to an aparently infinite volume universe, that has not collapsed. In the model of 1917 he tried to describe a universe that exists in a steady state, that is, not collapsing and not expanding. The creation of the big bang model was an inadvertant by-product of his classic 'cylindrical universe,' because such a steady universe must have a mysterious cosmological constant holding it up, and keeping it from collapsing.