A few weeks ago I was watching a historical Chinese drama with my parents. A totally normal teenage thing to do…! Although it may seem dorky, I enjoyed this show about the ruthless fighting between the Emperor’s concubines during the Qing Dynasty. But I noticed something weird right off the bat. These concubines lived in days with named time periods, and used a strange lunar calendar, so when wife A wanted to poison wife B at the hour of mao on the last day of the lunar month you can imagine how confused I was. But eventually I figured out they lived by this strange schedule with 12 time periods in a day, each with a different names and containing 2 of what we call hours in each time period. The lunar calendar is based off movements of the moon, which vary from month to month and year to year, unlike our current calendar. This really made me start thinking about how arbitrary the idea of time was, and how in reality, time-keeping is just a strange man-made concept to create some type of order and conformity between people.Nowadays, time-keeping is such a large part of our daily lives, we let it dictate our lives without giving it much thought. We wake up at a certain time, have to be at school or work by a certain time, eat lunch at a certain time, come home at a certain time, eat dinner at a certain time, and go to sleep at a certain time. WIthout this man made invention of time-keeping we wouldn’t be in the room right now, as this round had to start a certain time. But it wasn’t always this way. Today we’re gonna explore what exactly time-keeping is, then move on to discuss some of the ancient time-keeping methods, how timekeeping evolved over time-no pun intended, before finally looking at how modern timekeeping was born and what methods we use to keep track of our time.Timekeeping, according to the Collins English Dictionary, is the process or activity of timing. Timekeeping is different from time itself, which is the indefinite continued progress of existence and events in the past, present, and future regarded as a whole, according to Merriam-Webster. Therefore, time has always continued on, it was there for our first ancestors and the organisms they evolved from, and will likely continue for the rest of our lives as we know it. Timekeeping, however, is essentially measuring time, and is a manmade concept. It is a relatively recent human desire-most likely around 5000-6000 years old, and most likely originated from the Middle East and Northern Africa. So now that we know what time-keeping is, and how it differs from time itself, we can explore the earliest forms of timekeeping.Some believe that the Sumerians, who were thousands of years ahead of the ancient Egyptians, started timekeeping, but much of the proof for this is rather speculative. The first group we can prove took timekeeping seriously as part of their culture was the Ancient Egyptians-I mean they built sky-high pyramids and invented timekeeping, they’re like that one cousin your parents always compare you to. Like Daniel, why can’t you be more like your cousin Ancient Egypt! Well anyways, the Ancient Egyptians used two main methods to keep track of time: the sun and the stars, and the Greeks and Romans began to use water to do the same thing.Using the Sun. In 3500 BCE Ancient Egyptians built obelisks, four sided monuments, and placed them in locations to cast shadows using the sun. The moving shadows acted as a type of sundial, allowing the Ancient Egyptians to divide the day into two parts, before noon and afternoon. They also showed the longest and shortest days of the year, by seeing when the shadow at noon was the longest or shortest. Eventually, further subdivisions would be added around the base of the obelisks. Then 2000 years later, in 1500 BCE the Egyptians built a more accurate shadow clock, or what we know today as the sundial. A sundial tracks the movement of the sun through shadows onto a surface measured by hour and minute lines. Most of the time the larger sundial would be the more accurate one, due to the lines being able to be divided into smaller periods of time, but a sundial too large causes shadows to become fuzzy, making the sundial harder to read. In the quest for the perfect sundial, the sundial evolved many times, becoming vertical and bowl-shaped, among many other variations.Around 600 BCE the Ancient Egyptians improved upon the sundial by using the stars. They used the merkhet, the oldest known astronomical tool, which uses a string with a weight on the end to measure a straight vertical line. Two merkhets were used to develop the North-South line by lining them up with the Pole Star, allowing for measurement of nighttime hours when the sun was not present, as it measured when certain stars crossed a marked line, telling what time during the night it was.Water clocks were the first instruments not using celestial bodies to tell time. Water is also like that overachieving cousin-we need it to survive, it can clean up messes, people fight wars over it, and it allowed people to measure time more accurately. Wow, impressive! The Greeks used clepsydras, which is Greek for water thief, by dripping water through a narrow opening and accumulated the water in a reservoir where a floating object, carrying a pointer rose, marked the hours. In the Middle East, a less accurate variation of this was used where water would drip out and land in a bowl until it sank. Despite these clocks not being able to tell time more closely than a large fraction of an hour, they were still used in parts of Africa until the early 1900’s! But between 100 BCE and 500 AD, Greeks and Romans developed more elaborate water clocks. They added complexity to make the flow more constant by regulating the pressure. These fancier water clocks rang bells;opened doors to show little figures of people, and even moved astrological models of the universe. They can be thought of as the inspiration for modern cuckoo clocks, like this one, which are in the homes of millions (of elderly -idk about this part) people today.Now that we’ve covered the development of older timekeeping in the Middle East and Europe, what about in Asia? Well one example we have is from China, where the clock tower built by Su Sung and his associates in 1088 AD is located. It used a water-driven technology invented in 725 AD and was over 30 feet tall, with an automatically rotating celestial globe, and five front panels with doors that showed mannequins, who rang bells and held tablets indicating the hours of the day. Now that’s a fancy water clock.The next stage of development and modernization of timekeeping was the mechanical clock, which is still used in some parts of the world today and has arrangements of gears and wheels that spin and are turned by weight attached to them. As the weights were pulled down by gravity, the wheels were forced to turn regularly and consistently. A pointer, attached to the wheels, marked the hours. This type of clock was invented in Medieval Europe and became commonly used in churches and monasteries to tell time for regular prayers and church attendance accurately. Eventually, Galleo realized that the constant swing of the pengellum would be the best thing to regulate the movement of the wheels in the clock and in 1656 Dutch Astronomer Christian Huygens made the first successful pendulum clock. This was a huge step and reduced the error margin to around 10 seconds per day. Then, In 1721, George Graham reduced the pendulum clock’s error margin to within a second a day by compensating for changes in the pendulum’s length caused by temperature variations. The mechanical clock continued to develop until it achieved an accuracy of a hundredth of a second a day and eventually became what we know today as the ‘Grandfather Clock’. These clocks became the golden standard in the 19 century and are still in use today1So that brings us to modern times. As most people know, the common material used in clocks and watches today is Quartz. These clocks are reliant on the electric property of the quartz crystal. When an electric field is applied to a quartz crystal, it changes the shape of the crystal itself. If you then squeeze or bend it, an electric field is generated. When placed in an electronic circuit, the interaction between the mechanical stress and the electrical field causes the crystal to vibrate, generating a constant electric signal that can be used to measure time. It sounds complicated but basically the crystal changes shape, generating an electric field and then that field can interact with mechanical stress, generating a constant beat that is used to measure time. This method continues to be popular today because it is both cheap and reliable. Most likely your watch or alarm clock relies on this quartz system.But today most people use their phones and other electronic devices to check time. How is the time in these generated? It most likely is synchronized with one of the world’s most accurate cesium atomic clocks. An example would be the cesium atomic clock at the National Institute of Science and Technology (NIST), in Boulder, Colorado, which is the nation’s primary frequency standard that is used to define Coordinated Universal Time (known as UTC), the official world time. These atomic clocks are incredibly complicated, essentially relying using a consistent flow of atoms to create a consistent wave that keeps time. These clocks are recognized as the most accurate ones we have today and are seen as the ‘correct time’. So now we know how we get the time we use the most-our phone’s time.But what about the future of timekeeping? I mean it’s been constantly developing so there has to be something new. Many believe the future of timekeeping could be optical atomic clock, which measures atoms or ions that are moving at frequencies 100,000 times faster than cesium. These clocks are much more precise than cesium atomic clocks because of these faster vibrations, which cause them to, in turn, “tick” faster. Experiments are still going to fix some issues with the downtime but scientists in Germany believe these clocks could definitely replace our current cesium atomic clocks. Wow-what a journey it’s been. We went to Ancient Egypt to discover how they used the sun and stars for timekeeping, then we went to Greece, Rome, and the Middle East to see how water clocks were used, before seeing the magnificent water clock tower in China, and then saw the invention and evolution of mechanical clocks, before seeing the modern appeal of using quartz watches and clocks and then finally exploring the most accurate clocks we have today: atomic clocks. We then took a peek at what the future of timekeeping could look like, with optical atomic clocks. We can clearly see how time was originally measured in a simplistic way and timekeeping developed into more accurate and complex systems. So next time that alarm clock rings, remember how much work has been put into it so this modern luxury can be used by you.