What is the Big Bang Theory/Inflation Theory

The Big Bang theory is the theory in which astronomers believe the universe has expanded from an initial point for over a billion years. In 1912 Vesto Slipher recorded the observation of a spiral nebula and recorded the red shift. What he recorded was that the nebula kept moving away from the earth. In 1924 Edwin Hubble recorded that the nebula was not a part of the milky way. In 1927 priest Georges Lemaitre calculated and made the assumption that the earth is expanding because the distance of the galaxies kept growing bigger and bigger. They have found a light between the distance of the galaxies and the red shift.They believe the universe will officially reach a maximum density and temperature. George Gamow predicted the cosmic microwave background radiation which was the radiation that existed during the Big Bang. During the recombination era, they allowed microwave radiation to travel through the universe. It could still be observed today.In the 1960's and 1970's many astronomers tried to deny the big bang theory. In 1980 Alan Buth formed the inflation theory. The Inflation Theory was a theory in which they say the earth was expanding because of a negative-pressure vacuum energy.  In 2001 the NASA Program gave evidence in which to back up the Inflation Theory.