Aristotle & Ptolemy: Geocentric Universe.
Throughout history Greek philosophers such as Aristotle, Ptolemy, and Copernicus, tried to figure out the universe and its structure. Sometime between 384 and 322 BC Aristotle had believed that the universe was spherical and dividend into two worlds, the astronomical and the sub lunar world. Aristotle models didn't explain what has been observed about the motion of the stars and planets so that led Ptolemy to come up with his model sometime between 100AD and 170AD, which explained the retrograde motion. This is what people believed until Nicholaus Copernicus came up with his theory of Heliocentric between 1473 and 1543.
In Aristotle's model of the universe he believed it was made up of four elements, earth, water, air, and fire. In the astronomical world it contained a fifth element called ether. In his model it consisted of fifty-six spheres interlocked within one another with the outermost sphere being called the Prime Mover because all other spheres got there motion from it. Then Ptolemy disagreed with Aristotle's model because it didn't explain the observed motions of the stars and planets. He used a theory of epicycles, which are secondary orbits for planets to explain the retrograde motion of the stars and planets. Then Nicholaus Copernicus came up with his theory of a Heliocentric Universe were the sun was the center of the universe instead of the planet earth and all the planets rotate around the sun including earth.
Even today we still believe Copernicus's model to be true that our universe consists of planets evolving around the sun. This will probably not be the last theory that humans come with that we hold as true. As science and technology advance we will discover new things to help us understand the universe better and someday someone else will come up with a new model for how the universe operates. Even someday someone may find out how all of universes operate and how they all tie into one another.
