The big bang theory is the prevailing cosmological model for the observable universe from the earliest known periods through its subsequent large. An expanding universe generally has a cosmological horizon, which, by analogy with the more familiar horizon caused by the curvature of earth. The earth is a plane, not a planet. Believe your eyes and common sense, the earth is flat and motionless. The sun, moon, and stars all revolve around us. To create the universe. Prior to the twentieth century, before the big bang theory had been developed.