*Updated 2024
Astronomers, archaeologists and theologians, among many others, have pondered the nature and meaning of “time.” We all know what time is until someone asks us to define it. Then we’re at a loss for words. Worse yet, the more we think about time, the more complicated the subject becomes, especially if we let the fantasies of science fiction creep into our minds.
During the pandemic, when people all over the world stayed at home for extended periods of time, we had nothing but time on our hands to ponder the nature of time as we perceive it. Is it linear, meaning does it move in only one direction, or is it cyclical, evolving around cycles, such as seasons? While many people in the modern era seem to agree that time is linear, for most of humankind’s existence, time has been considered cyclical and rhythmic.
Below are three arguments stating that time is linear and three more stating that time is cyclical.
Three Reasons Time is Linear
Time is Irreversible
Much to the chagrin of H.G. Wells and other writers, not to mention of movie and theater fans of characters like Marty McFly, it’s simply impossible to travel back in time. As living beings, we are born, we age, and we die, in that order. We know about the past, but we can’t, by definition, know about the future. This is because time is unidirectional. This is not perception, it’s physical reality.
Things Fall Apart
The Second Law of Thermodynamics suggests that time is linear and unidirectional because things in our universe go from a state of order to a state of (increasing) disorder. My hot cup of tea becomes cold, it doesn’t heat up. A dead body decays, it doesn’t come back to life. Cars wear out. And I’m aging. I can deny that these things happen, but one day I won’t be around to deny them anymore.
Time is Cumulative
Time is linear because of the different and cumulative ways we can record and measure it. Our Smartphone stopwatches measure time in milliseconds. This may be an absurd level of precision for daily life, but it is increasingly important as we push the limits of human athletic performance. We can also measure time by counting the number of times the Earth goes around the Sun, just as humans have done for thousands of years. If counted, this shows linear progress from a starting point onward. Or we can measure the vibration of cesium-133 atoms, as is done to set International Atomic Time. That global standard is so accurate that it will take 1.4 million years for it to be off by a full second. These natural phenomena can be recorded in long, cumulative and linear sequences.
Three Reasons Time is Cyclical
The Earth, Moon, and Sun Move in Repeating, Elliptical Patterns
All of our most common time measurement systems we use in daily life are cyclical: The repetition of 60 seconds into a minute, 60 minutes into an hour, 24 hours into a day, seven days into a week, (roughly) four weeks into a month, (roughly) three months into a season, and four seasons into a year. As such, don’t our feelings of déjà vu and the idea that history repeats itself support the notion that time is cyclical? If time were truly and naturally linear, wouldn’t we use linear, metric counting measures that proceed from a single starting point towards infinity, like distance measurements do?
Humans Haven’t Really Needed Structured, Linear Ways to Measure Time
Until recently, the lives of agricultural, nomadic, and even urban peoples were governed by the endlessly repeating seasonal round. Calendars, which portray time as a linear concept, are a recent phenomenon when compared to the long-term existence of our species. The earliest calendar may have developed as early as 10,000 years ago; well-documented calendar systems don’t become common in the archaeological record until within the last 5,000 years. Our species is 200,000 years old; for at least 95% of humankind’s existence as a species, time was cyclical and circadian.
Calendars are Cultural, Man-Made Constructs
Have you noticed that our calendar years, i.e., linear timeframes, are counted as cumulative units from a particular starting point? This is because annual calendars are used by the political and religious powers to mark events they deem important, like the birth of Jesus, not natural or physical events or processes, like the origin of life on earth. What’s the difference between the Hebrew, Chinese, Gregorian, and Mayan calendars? Ultimately, and from the perspective of time itself, not much. These calendars have different origins, starting points, counting systems, and holidays that are relevant only to people, not animals, plants, or the planet. In the end, each of these calendars is nothing more than a cultural construct based on local political, religious, scientific, and economic systems created by humans.
The Bottom Line: Humans have a complicated relationship with time. Our modern lives are almost ridiculously structured by linear time and its precise measurement. However, our human ancestors, and some of our relatives today, live by a different understanding of time, one that it is cyclical, circadian, and rhythmic. There may be wisdom in that. Do you have a linear or cyclical view of time?
