Hawking works with black hole theory, among others, notably the combination of quantum mechanics and general relativity. Sir Isaac Newton generates the physics that predicts the movements of heavenly bodies accurately enough, and Albert Einstein brings forth the general theory of relativity, which implies that the universe started with a big bang from a singularity of infinite mass and curvature, a single point with no dimensions. It is not the center of the universe, and in fact occupies an insignificant spot within the whole. The importance of the earth dimishes with this view. Additionally, many other galaxies are observed with ever greater clarity. The earth indeed orbits the sun, but the sun orbits the galaxy, which is full of stars. Later observations with telescopes based on Galileo's early instrument reveal the true nature of the earth and the sun in relation to the universe, which grows much larger than the early conceptions. Copernicus contributes the idea that the sun is the center, and Galileo concurs.

He begins with the earlier ways people understood the universe and moves to the present day, where many theories exist for specific pieces of the whole picture, but none of the theories cover the universe in its entirety.Īristotle's thinking that everything is made up of only four elements and absolute position and time characterize the universe leads to Ptolemy's idea of heavenly spheres, both assuming the earth is at the center of the universe. Hawking writes about the history and present thinking of theoretical physicists in a manner the average person can understand.

A brief history of time pages