Humans have been trying to make sense of time since, well, the beginning of time, at least human time. Almost all religions and cultures have creation stories that touch upon time and are constructed around cycles of nature. Ancient Jews were no exception. The Jewish calendar, now in the year 5780, incorporates lunar, solar and daily cycles, as well as the weekly one reflecting the Torah’s description of the seven days of creation. It is the thread tying together prayer, ritual and holidays marking seasonal milestones and past events critical to the formation of the Jewish people. Jewish time also takes fertility cycles, both human and agricultural, into account. And, as elsewhere in the Western world, Jewish time is generally linear, with one event following another. But there are exceptions: The Jewish mystical tradition of Kabbalah, for example, often looks upon time as an illusion. Of course, religion is just one lens through which to view time. Astronomers, philosophers and scientists have pondered whether “time” actually exists and have attempted to define, measure and describe it.
From among thousands of beliefs and theories about time, we’ve selected just a few. We begin with…
Indigenous peoples have creative ways of experiencing and expressing time that often fall outside Western linear models. The Pirahã of the Amazon rain forest have been said to exist totally in the present, and their language has no word for “time.” The language of the Yupna of Papua New Guinea portrays the future as uphill. And the Aymara of the Andes envision the past in front and the future behind. From the Maya perspective, time is sacred. At their peak in Mesoamerica, the Maya created complex, precise calendars based on careful study of recurrent astronomical and natural cycles, including the observable motion of the sun across the sky, the phases of the moon, the gestational period of human beings and the growing cycle of corn. One is the Maya Long Count calendar, which famously ended in 2012, completing a 5,126-year cycle, and beginning a new one; another is a 260-day calendar that is believed to be based on the duration of a human pregnancy. Maya calendars continue to mark agricultural cycles today, and are used by Maya farmers to conduct ceremonies and make offerings throughout the corn growing season.
The ancient religions of Asia, principally Hinduism and Buddhism, view time as eternal, going through infinite phases of creation and destruction. There is no one genesis but many, since time is cyclical, like a wheel, with no beginning and no end. The best-known manifestation of this repetitive narrative of birth and reincarnation may be the mandala. It’s of Tibetan origin, even though the name is Sanskrit for “circle” or “discoid object.” The Vedas, Hindu texts that date back to the second millennium BCE, detail a complex system of time and estimate that each cycle lasts 4,320 million years. Civilizations as well as individuals experience these endless cycles. The universe, too, undergoes an infinite number of deaths and rebirths, an idea that roughly corresponds to modern scientific cosmology. Other natural cycles—such as day and night, the moon and the tides, the seasons—demarcate daily life. The Buddha, Siddhartha Gautama (born in Nepal in 563 BCE), had a fairly straightforward approach to time: Don’t trouble yourself over unanswerable questions, but focus on seeking enlightenment in the here and now.
Greek mythology features Chronos, the god of time. When the search for knowledge replaces gods, early Greek philosophers such as Antiphon, Parmenides and Heraclitus hold conflicting views of time. Respectively, they argue that time is not a reality but a measure; that reality is limited to what exists here and now, so the past and future are unreal and imaginary; and that the flow of time is real and the essence of reality. “No man ever steps in the same river twice, for it’s not the same river and he’s not the same man,” Heraclitus says. Plato, in the 4th century, posits that the creator created time in the same instant as the heavens, but bows to science in conceding that time must be connected to the motion of heavenly bodies. Aristotle, often considered the most important philosopher of his time, is more practical: Time, he says, does not exist on its own but is essentially a measurement of change. It is infinite, in that the universe has always existed and will always exist, and time is eternal. Aristotle’s views on time would influence thinkers for centuries to come.
Scripturally, the Abrahamic world starts the clock at the moment of creation. “In the beginning God created the heavens and the Earth,” opens Genesis in the King James version of the Bible. (The Quran of Islam goes down the same path, though it diverges a bit on what happened on day seven.) The great Christian philosopher and theologian Augustine (354-430) explicitly addresses time. “The earth is not eternal; the earth, as well as time, has both a beginning and an end,” he says, but man was “brought into existence to endure eternally.” Human existence proceeds through birth, death and immortality, and human history from creation to the second coming of Jesus Christ and the end of days. (Jewish tradition also includes a belief in redemption and physical resurrection, but past Messianic failures have left most Jews wary.) The Book of Revelation finishes the New Testament with a terrifying spectacle of a lamb with seven horns and seven eyes, a horse ridden by Death, and seas of blood. Once Jesus triumphs over evil at the battle of Armageddon (the ancient city of Megiddo in northern Israel) and Satan is cast into a lake of fire, time as we know it on Earth comes to an end.
Many medieval thinkers address Aristotle’s assertion that the universe has no beginning. Rabbi Saadia Goan ben Joseph, a prominent 9th-century Arabic-speaking Jewish scholar who lived during the Abbasid Caliphate, studies Aristotle and determines that the past cannot be eternal. Twelfth-century Christian mystic Hildegard Von Bingen has a vision of a cosmic egg universe that surges flames, emptying and filling itself like a womb, as it moves through time until its demise. Catholic philosopher Thomas Aquinas (1225-1274) observes that time and action (motion) are always perceived in relation to one another: Time is associated with numbering the sequence of actions. Time, he argues, could not have existed before man, because without humans, there was no one to number the actions. In the 14th century, John Duns Scotus and William of Ockham refute Aquinas, insisting that time exists independent of action. That same century, French theologian Peter Aureole states that time exists independent of humans. “Time simply is,” he says, adding that time exists as a constant flow, but humans divide it into past, present and future.
As much as anyone, the British scientist Sir Isaac Newton (1647-1727) is the bridge between Renaissance giants such as Nicholas Copernicus, Galileo Galilei and Johannes Kepler and the modern age of science. He formulates the laws of gravity and motion that are standard until Albert Einstein comes along and turns thinking about time and space on its head. According to Newton, absolute time (sometimes known as “Newtonian time”) exists independently of any perceiver and progresses at a consistent pace throughout the universe. It is measurable but imperceptible and can be truly understood only mathematically. Newton also asserts that gravity is an attractive force between two objects, an explanation that is widely accepted until Einstein, who adds time as the fourth dimension of space, shows that gravity is actually the result of the mass of objects curving space-time.
Albert Einstein was light years ahead of the pack in more ways than one. His special theory of relativity (1905) and general theory of relativity (1915) disputed Newton’s ideas of absolute time and showed that it is the speed of light that is absolute. Therefore, Einstein argued, if light has a speed, then time and space are far more fluid than Newton would ever have thought. Humans occupy relative time: Time elapses at a different rate for one person than it does for another if they’re moving relative to one another. Einstein also postulated that gravity can actually bend time, warping the very fabric of our universe. Einstein had a lot to say about the nature of time generally. “The distinction between the past, present and future is only a stubbornly persistent illusion,” he wrote after the death of a friend.
Einstein lived to the age of 76, long enough to see his theories proven and expanded, although not always in ways to his liking. His theoretical scribblings, made when he was a young man holding down a day job at the Swiss Patent Office, anticipated satellites, space travel, computer simulation and the Hubble Space Telescope, which can see stars being born and dying as well as galaxies trillions of miles away. His work helped pave the way for the theory of the “Big Bang,” the massive explosion scientists say gave birth to the universe some 13.8 billion years ago. Notwithstanding all these scientific advances, physicists continue to debate the nature of time. At a 2016 conference in Canada on the subject of time, 60 physicists pondered weighty questions such as whether time is fundamental (is there a fundamental unit of time that cannot be broken down further?) or emergent (affected by changes in the universe), according to an account in Quanta Magazine. They agreed on a few things: “Teacups shatter but do not spontaneously reassemble; eggs can be scrambled but not unscrambled.” While the mystery of time remains unresolved, it is easier than ever before for humans to tell time on a daily basis. Thanks to atomic clocks, we can measure the precise length of a second, the base unit of modern timekeeping. So together, along with our synchronized devices, we can continue to explore the nature of time and ask: Does anybody really know what time it is?