Neil deGrasse Tyson discusses the history of the scientific method. He looks at the Michelson-Morley experiment and he helped disprove the existence of the luminiferous aether. He examines how mathematics and physics were used to predict the location of the planet Neptune before it was discovered. He also examines how irregularities in the orbit of Mercury helped to establish Einstein's theory of relativity. Finally, he looks at historic models of the know universe by Ptolemy and Copernicus and discusses some of the theological ramifications of science.