The universe is commonly defined as the totality of existence, including planets, stars, galaxies, the contents of intergalactic space, and all matter and energy. Definitions and usage vary and similar terms include the cosmos, the world and nature.
Scientific observation of earlier stages in the development of the universe, which can be seen at great distances, suggests that the universe has been governed by the same physical laws and constants throughout most of its extent and history. The universe is believed to be at least 93 billion light years in diameter and has existed for about 13.7 billion years, since it was created by the Big Bang.
There are various multiverse hypotheses, in which physicists have suggested that the universe might be one among many universes that likewise exist. The farthest distance that it is theoretically possible for humans to see is described as the observable universe. Observations have shown that the universe appears to be expanding at an accelerating rate, and a number of models have arisen to predict its ultimate fate.
Famous quotes containing the word universe:
“Why inspire in us a horror of our being?... To look upon the universe as a prison cell and all men as criminals about to be executed is the idea of a fanatic.”
—Voltaire [François Marie Arouet] (16941778)
“Without poets, without artists, men would soon weary of natures monotony. The sublime idea men have of the universe would collapse with dizzying speed. The order which we find in nature, and which is only an effect of art, would at once vanish. Everything would break up in chaos. There would be no seasons, no civilization, no thought, no humanity; even life would give way, and the impotent void would reign everywhere.”
—Guillaume Apollinaire (18801918)
“For the universe has three children, born at one time, which reappear, under different names, in every system of thought, whether they be called cause, operation, and effect; or, more poetically, Jove, Pluto, Neptune; or, theologically, the Father, the Spirit, and the Son; but which we will call here, the Knower, the Doer, and the Sayer. These stand respectively for the love of truth, for the love of good, and for the love of beauty.”
—Ralph Waldo Emerson (18031882)