The arrow of time, or time's arrow, is a concept developed in 1927 by the British astronomer Arthur Eddington involving the "one-way direction" or "asymmetry" of time. This direction, which can be determined, according to Eddington, by studying the organization of atoms, molecules and bodies, might be drawn upon a four-dimensional relativistic map of the world ("a solid block of paper").
Physical processes at the microscopic level are believed to be either entirely or mostly time-symmetric: if the direction of time were to reverse, the theoretical statements that describe them would remain true. Yet at the macroscopic level it often appears that this is not the case: there is an obvious direction (or flow) of time.
Famous quotes containing the words arrow and/or time:
“Anton Petrovich turned into the passage, followed the arrow to men, mankind, human beings, marched past the toilet, past the kitchen, gave a start when a cat darted under his feet, quickened his step, reached the end of the passage, pushed open a door, and a shower of sunlight splashed his face.”
—Vladimir Nabokov (1899–1977)
“God will take care of you for me. I am my God’s. I belong to him, I go a short time before you, and I want to meet all in heaven, both white and black.”
—Andrew Jackson (1767–1845)