History of Time (Part 2/2)
…and time measurement
Interviewer: Aco Momčilović, psychologist, EMBA, Owner of FutureHR, Ph.D. Student @ University of Dubrovnik; Co-Founder and Co-Director of Global AI Ethics Institute.
Interview with Mirko Sardelić, Ph.D., Research Associate at the Department of Historical Studies HAZU, Honorary Research Fellow of the ARC Centre of Excellence for the History of Emotions (Europe 1100–1800) at The University of Western Australia; formerly a visiting scholar at the universities of Cambridge, Paris (Sorbonne), Columbia, and Harvard.
Part 1 is available on this link.
4. How did mechanisms of time measurement develop through time? What were the ways of time measurement in previous centuries?
One of the first features of timekeeping that one notices is that one hour has 60 minutes, with 60 seconds in each minute. Alongside culture that shapes the perception of time in its members, it has always been mathematics that formulated and divided time into segments. Today the most widely used numerical system is decimal (base 10), but ancient civilizations used different systems, with bases such as 12, 40, or 60. The base 60 is convenient as it is easily divisible with the first six numbers, as well as by 10, 12 (the number of lunar months in a year), 15, 20, and 30. The same base used by the Babylonians is ‘responsible’ for the fact that there are 180 degrees in a triangle or 360 degrees in a circle.
The first objects that were used for daily timekeeping were shadow and water clocks. More than 5,000 years ago, Egyptians built tall obelisks whose shadows on the floor indicated the time of the day. The oldest known description of a water clock (clepsydra) is some 3,500 years old, and it is also of Egyptian origin.
The big problem for calendars has always been a discrepancy between the solar year and the lunar year. The Romans measured the time from the foundation of their capital (ab Urbe condita, in 753BC). Julius Caesar in 45 BC initiated the first reform of the calendar, designed by Greek mathematicians and astronomers, the most prominent of whom was Alexandrian astronomer Sosigenes. The next crucial reform in the Western world happened in 1583 when Pope Gregory XIII initiated a reform based on contemporary advancements in astronomy that showed that Caesar’s astronomers overestimated the length of the year by little over 11 minutes. After 1600 years (from Caesar to Gregory) the cumulative change was some 10 days. One of the issues was that not all European countries adopted the reform at the same time — e.g., Greece and Russia did that in the early 20th century. This caused quite a confusion in traveling; one of the most popular anecdotes is related to American Olympians coming to the first modern Olympics in Athens (1896) later than they wanted to due to the differences in the calendar.
The invention of modern clocks in Europe is related to the activities of the Church, which often employed the most skilled artisans for various works. Since the bell was used to signal a particular hour, the two words got interconnected. The Latin word for bell, clocca, evolved in the word for the timekeeper: the clock.
Christian Huygens invented a pendulum clock in 1657, and it increased the accuracy of clocks by 50 times, and the errors were measured in seconds rather than minutes after his invention. A French physicist Foucault used the pendulum to show that the Earth spins and that it takes 24 hours to do it. Pendulum clocks remained the most accurate time-keeping devices till the invention of quartz clocks in 1927. However, the future of timekeeping was on the atomic scale.
Although it was already Lord Kelvin’s (late 19th century) idea that atoms could be used for timekeeping, it was only after WW2 that this idea was elaborated on and widely adopted. In 1967 the International System of Units standardized one second in relation to the natural frequency of the cesium atom: the second was defined as exactly 9,192,631,770 oscillations or cycles of the cesium atom’s resonant frequency. In recent decades (since 1983) even the definition of the meter is derived from that of a second by fixing the speed of light in a vacuum to be exactly 299,792,458 meters per second, and then defining 1 meter = 1 / 299792458 seconds. Thus, the accurate measurement of a basic time unit equals to an accurate measurement of a basic length unit, underscoring the importance of time in the modern era.
5. Was the perception of time a significant factor in forming social and other relations between civilizations/cultures and inside a single culture?
For millennia humans were obsessed with attempts to create a framework in which time can be put in relation to humans, to nature, to God. In many cultures god(s) either created and mastered time or existed outside time — because, as Plotinus argued, to exist within time means to exist imperfectly.
Vision, hearing, and smelling — key elements of getting around in our environment — all have a particular organ dedicated to the activity. Unlike those, a sensory organ that detects time does not exist, and there are no internal physical measurements of time. Our brain creates the feeling of the passage of time which, like other subjective experiences, make the sense of time subject to distortions and illusions. This can create difficulties for some things, but there are fascinating advantages. We all tend to forget that our brain is a sophisticated time machine, even more, the best one ever built. Humans managed to master the ability to understand time and can mentally project themselves back into the past or forward into the future, thus performing a mental time travel. Not only can we relive events that happened decades ago, but we also attach strong emotional content to some of these traumatic or joyful experiences. Those then can help us maneuver through our possible futures that we daydream about or plan. Humans started to develop more significantly once they realized they can affect and shape their future through their actions in the present.
6. Today, we can find popular videos that are summing up most of the earth or space-time from the beginning to this moment or the end. How can we put the timeframe of life on Earth into a bigger perspective?
The time dimension can have multiple scales. Scientists argue that time came into existence alongside visible space with the Big Bang ca 13.7 billion years ago. Observing distant galaxies allows us to see back in time — i.e., what they looked like millions of years ago. Geological age can be estimated through fossil remains and carbon dating. Cellular age is limited by the length of the ends of the chromosomes (telomeres). The lifespan of all forms is determined by various physical, chemical, and biological processes. The life cycle of stars can range from several million years to a hundred of billion years (red dwarfs). We can put that in relation to the longest lifespans of animals and plants on Earth: Greenland sharks can live up to 500 years, while mayfly lives only 24 hours. Giant sequoias can live up to 3,000 years — General Sherman in California is estimated to be 2,500 years old. On the other hand, some plants, such as the model plant Arabidopsis, have a life cycle of just two to three months.
First Homo sapiens appeared in Africa some 200,000 years ago and developed the ability to use language 50,000 years ago. The oldest human civilizations are less than 10,000 years old. In the geological time frame, this is just a tiny fraction of the life of the Earth, while we perceive it as an incredibly distant past.
7. Which philosophers before, and scientists today contributed to the exploration and perception of time as a topic?
In the Western world in the period around 500 BC, Greek philosophers discussed the nature and properties of time. The sophists proposed that it is not a reality, since the past and future are unreal and imaginary. Philosopher Zeno of Elea (490–430 BC) set a number of philosophical problems (paradoxes) related to time and space — the most famous one being that Achilles might never catch the tortoise which has a considerable initial advantage. Immanuel Kant suggested that Time is merely an element of the systematic framework humans use to structure their experience.
As mentioned before, human perception of time was influenced by religions and philosophers, but some crucial advancements were made in the fields of physics, mathematics, and astronomy. Therefore, one contemplating time should consider scholarly works that explain the physical properties and the relativity of time. Nonetheless, this requires a lot of broad knowledge, and mastering some crucial concepts, which takes a long time, and generates more questions than it provides answers. Physicist Paul Davies has put it in a nutshell: “The scientific study of time has proven to be disturbing, disorienting, and startling”.
There are two major philosophical theories on the nature of time: presentism and eternalism. Presentism postulates that only the present is real, while the past is a configuration that once existed, and the future is undetermined. On the other hand, eternalism proposes that the past and future are equally real as the present, and there is nothing special about the present.
The study of time in neuroscience was somewhat neglected (due to its complexity and relation to other issues) in the 20th century. However, in this century, there has been much more interest in the topic, primarily in relation to how the brain stores memories. The memories keep the information from the past with the purpose to help humans anticipate the future — this is why the temporal factor is crucial.
8. Why do humans perceive time the way they do? What are the dangers of our evolution-developed ways of perception in today’s world of much faster and even accelerating pace of change of things?
The human brain uses more familiar concepts to explain and substitute some more complex ones, and this can be seen in our vocabulary. For example, the concept of space is more familiar to us than the concept of time, therefore we say: long/short period of time. Long and short are primarily space-related adjectives. One of the theories proposes that humans adapted the circuits related to understanding and representing space to be able to do the same with time.
Although humans have developed amazingly sophisticated instruments to measure time, it has remained an evasive concept. Some of the struggles is encapsulated in phrases such as ‘Time flies!’ or ‘Run against the clock’. The Red Queen effect is an increasingly relatable concept in present-day society, whereby one needs to constantly work hard not to fall behind. It is paradoxical because humans have advanced in so many aspects and yet it seems that they struggle more to keep up with the pace of the modern world.