Tracing the ancient origins of time from early mankind to our modern understanding of the concept, Eoin Murphy tells the story of how time came to be.
Found in the Lebombo Mountains between South Africa and Eswatini and shown by radiocarbon dating to be ~44,000 years old, the Lebombo bone is the oldest known archaeological artefact. The fibula bone from a monkey contains 29 distinct notches, which are strongly believed to have been used as a counting tool or basic calendar used to track the phases of the moon.
Bone Bone. Photo: Robert Hart, The McGregor Museum, Kimberley, South Africa
By 12,000 years ago sites had been built containing symbols and structures that suggest their use as early calendars. Gobekli Tepe, located in modern day Turkey is believed to be the oldest human settlement in the world. V-shaped sculptures have been found at the site, which some archaeologists believe may represent the solar calendar.
Sites such as Newgrange and Stonehenge dating back some 5,000 years show the understanding that humans developed to coincide with the solstices. As amazing as this was, what was happening in the east was even more amazing.
The Egyptians and Sumerians both had 12-month calendars. The calendars weren’t perfect, but they were pretty close. The Sumerians still had a year of 360 days, the Egyptians came very close to their year of 365 days.
Calendars are out of sync
The Romans also used a 12-month calendar. However, in their version there were only 355 days. Despite the addition of an extra month known as Mercedonius every two or three years, by 46 BC it was estimated that the Roman calendar had gone 90 days.
To remedy the situation, Julius Caesar turned to his advisor, Sosigenes. A Greek philosopher and astronomer devised a plan to bring the public calendar back into sync with the sun. By adding two more months, and the month of Mercedonius, 46 BC there would be 445 days spread over 15 months. The longest year in history will be known as the ‘Year of Chaos’.
Despite future calendar years consisting of 365 days and a leap year in all four, by the 15th century the calendar had been moved back by 10 days.
Realizing that the Julian Calendar was based on the Earth revolving around the sun every 365.25 days, Aloysius Lilius found a system where the calendar would be based on a year of 365.24219 days. Instead of a leap year every four years (one hundred in 400 years), there will now be 97.
He also proposed skipping a leap year for the next 40 years, to gain ten days.
Lunario Novo by Aloysius Lilius. Photo: Biblioteca del Vaticano
Pope Gregory XIII made changes regarding the reduction of leap years, however he chose to restore 10 days by simply removing 10 days from the calendar. Thursday 4 October 1582 was followed by Friday 15 October 1582 and to this day our calendar is known as the Gregorian Calendar.
Development at the end of time
As early as the sixth century, incense clocks are believed to have been used in China. Hourglass or sandglass clocks may date back even further, and some believe they may date back to the fourth century.
Another time-keeping device known as the water clock had been used in one form or another since the 16th century BC. But in 1088 AD, Su Song, a Chinese engineer would take this concept to a new level. He built a hydro-mechanical clock tower 12 meters high, using gears and mechanisms that would not be seen in Europe for centuries.
Throughout the 14th century, the rate of development in the field of timekeeping exploded in Europe. In 1336, the first clock believed to strike the hour using a bezel and a foliot escapement was engraved in Milan.
Then in 1371, Henri de Vic built and installed a clock in the tower of Charles V’s palace in France. The oldest public clock in Paris, which still exists today, would be the foundation of all timekeeping developments over the next 300 years.
The 24-hour system and division into 60 minutes had been established by the Babylonians and Egyptians long ago. But with the introduction of modern watches, time has become a part of everyone’s life.
Scientific revolution
In the late 15th century Leonardo da Vinci is believed to have produced the first known drawing of a pendulum.
Then, almost a century later Galileo discovered that the constant swing of the pendulum depended only on the length and not on the weight. This discovery could lead to the creation of a pulsilogium, a device that can accurately measure a person’s heart rate. In time Galileo would realize that ordinary motion could be used to measure time accurately, eventually paving the way for scientific time measurement.
Although Galileo started building a pendulum clock, it was never finished. Inspired by the work of Galileo, Christiaan Huygens, a Dutch physicist would in 1656 patent the first pendulum clock. His invention improved the accuracy of timekeeping devices from 15 minutes per day to between 10-15 seconds per day, making it possible to now include minute and second hands in domestic clocks.
Horologium Oscillatorium by Christian Huygens (1673). Photo: Smithsonian Libraries
Great minds change time
In 1687 when Isaac Newton published ‘The Principals of Natural Philosophy’, he changed the way we define time by creating the Theory of Absolute Time. Newton thought of time as something that passes regardless of what happens in the world. This was contrary to the previously held view that time could not pass without change occurring somewhere.
However, when Einstein presented the Special Theory of Relativity in 1905 he challenged the idea that time was absolute. Instead he suggested that the closer an object is to traveling at the speed of light, the more time it slows down and the shorter the object becomes. In 1915, Einstein would develop his theory to include gravity in general relativity.
The theory of relativity changed the world, enabling modern technology such as GPS navigation. It also provided a theoretical basis for how time travel might be possible, although not as it would appear in science fiction films.
Stephen Hawking’s invitation to time travelers. Photo: Science and Industry Museum, Manchester
Although Einstein’s ideas so far should be compatible with all the analysis, physicists could not satisfy both general relativity and quantum mechanics (behavior of atoms and subatomic particles) in one theory. This has led some physicists to ask whether time is real or just an illusion?
But for now, the next time you look down at your wristwatch or check your phone, take a moment and think that the first steps of this amazing journey may have started with our ancestors looking up at the sky and asking: “Why?”
Written by Eoin Murphy
Eoin Murphy He is a teacher and a communication scientist. She is on the board of the Mary Mulvihill Association, which is holding its annual awards ceremony and Science@Culture lecture on Wednesday, May 20. Tickets they are free but extremely limited.
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