The timeless universe is the philosophical and ontological view that time and associated ideas are human illusions caused by our ordering of observable phenomena. Unlike most variants of presentism and eternalism, the timeless universe entirely rejects the notion of the reality of any time, arguing that it is exclusively a human illusion, and since the universe can know no time, no dimension of time can be permitted in any theoretical explanation of parts of the observable universe. All purported measurements of time must hence according to this view be correlation measurements between movements, as stated by physicist Ernst Mach in 1883:It is utterly beyond our power to measure the changes of things by time. Quite the contrary, time is an abstraction at which we arrive by means of the changes of things; made because we are not restricted to any one definite measure, all being interconnected.In a timeless universe the cosmos in its broadest definition is eternal, without beginning or end, and all physical processes operate within a timeless framework. Since fundamental problems related to time, such as the Arrow of time and time travel, are still among the great unsolved problems of physics, discussions of timeless universes revolve around proposed solutions to these fundamental problems and paradoxa, and the related fundamental problems of philosophy and science. History The first person in recorded history to contemplate a timeless universe was the Ancient Greek philosopher Antiphon, who in the 5th century B.C. held that time was a man-made measure, rather than a real thing or substance. The same opinion was held by another Ancient Greek philosopher in the 2nd century B.C., Kritolaos. In the 2400 years since Antiphon, many different theories of possible timeless universes have been advanced, seeking to explain in whole or in part phenomena otherwise associated with or requiring the existence of time. Thinkers who have examined possible mechanisms responsible for such phenomena in a timeless universe include physicists such as Ernst Mach, Albert Einstein, Kurt Gödel and Carlo Rovelli, and timeless universes have been contemplated in works dedicated specifically to the subject by physicists such as John McTaggart, Julian Barbour and others. Research indicates that concepts of time are not universally known to humanity since the advent of behavioral modernity, but were developed by some cultures at some unknown point along the trajectory of the development of early human society. Indigenous tribes have been studied in Amazonas