The theory of Inflationary Cosmology was formulated by Edwin Hubble in the 1929. He discovered that the universe was indeed expanding, contrary to the scientific theory's of a static universe. This discovery even took famous physicist Albert Einstein by surprise!
What Inflationary Cosmology means is that the universe is continuously expanding! All the solar systems are moving away from each other in the universe. In his work, Hubble used the 'Hubble constant' to determine the size and age of the universe. It is odd that it is called the 'Hubble Constant' because the term is not constant as it changes with time.
The Hubble Constant was derived from measurements of redshift (speed moving away from earth) and a galaxies distance. Over the years, the Hubble Constant ha been revised and made more accurate. Hubble's own original prediction was 500 kilometers per second per megaparsec, but now the value is 50 km/sec/mpc.
This evidence of an expanding universe is key evidence in the theory of our universe's origin being the 'Big Bang'. The Big Bang could explain why the universe is still expanding because the momentum of the blast is still carrying our galaxy and others away from the center of the universe. The amount of mass in our universe will directly determine the futute and the ultimate fate of this universe. If the mass is large enough, then the universe will continue to expand more and more forever, isolating each galaxy from each other galaxy more and more as time goes on. Adversely, if there is not a large enough amount of mass in our universe, the gravity will eventually slow the expansion and the material will begin to fall toward the center of the universe where it originated! This is called “the Big Crunch” and it refers to the galaxy collapsing back in on itself!
