In the early twentieth century, Albert Einstein published his equations of general relativity and a Dutch astronomer, Willem de Sitter, found a solution to them that predicted an expanding universe. This, too, was a highly significant prediction because if the universe has been expanding and if galaxies are moving farther apart, this implies that in the past they once were closer together. If the universe has been “blowing up” for the duration of its existence, that means that it must have had an actual beginning.
Einstein, who didn’t realize that his equations suggested an expanding universe, was distressed to hear about this implication of his famous theory. When Russian mathematician Alexander Friedmann tried to persuade him, Einstein sought to prove Friedmann wrong. Actually Einstein was wrong. The great physicist was, by his own account, “irritated” by the idea of an expanding universe. He went so far as to invent a new force, the “antigravity” force, as well as a number called the “cosmological constant:’ to try to disprove the notion of a beginning. Later Einstein admitted his errors and called his cosmological constant the biggest mistake of his life.In the late 1920s, astronomer Edwin Hubble, peering through the hundred-inch telescope at Mount Wilson Observatory in California, observed through the “red shift” of distant nebulae that galaxies were moving rapidly away from each other. The number of stars involved in this galactic dispersal suggested an astoundingly vast universe, much bigger than anyone had thought. Some galaxies were millions of light years away. The impression that many people had long held of the stillness and changelessness of space was an illusion. Hubble noticed that planets and entire galaxies were hurtling away from one another at fantastic speeds. Moreover, space itself seemed to be getting bigger. The universe wasn’t, expanding into background space, because the universe already contains all the space there is. Incredibly, space itself was expanding along with the universe. Hubble’s findings, subsequently confirmed by numerous others, generated great excitement in the scientific community.
