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:
“Be not anxious to avoid poverty. In this way the wealth of the universe may be securely invested.”
—Henry David Thoreau (18171862)
“The kind of scientist who has no room for faith in his universe is rather old-fashioned nowadays.”
—Robert D. Andrews, and Nick Grindé. Dr. John Garth (Boris Karloff)
“The universe appears to me like an immense, inexorable torture-garden.... Passions, greed, hatred, and lies; law, social institutions, justice, love, glory, heroism, and religion: these are its monstrous flowers and its hideous instruments of eternal human suffering.”
—Octave Mirbeau (18501917)