Our civilization hinges on complex ideas from simple principles that almost nobody is aware of. So what would happen if civilization as we know it came to an end? Everyone who has visited the cinema in the last 30 years is likely to have an idea of what the end of the world might look like. But if there was a global catastrophe that set back the clock thousands of years, how might we go about rebuilding?
Time at the centre of our world
At the centre of everything we do in modern societies is centered around the bizarre concept of time. Everything -- from the trading hours of global markets, to the calls to prayer for the monk -- is synchronised to the beat of the day, hour, and minute. If a band of survivors were ever serious about rebuilding civilisation, a standardised method of time would be a very important ingredient.
But what is time? The question is difficult to answer because when we talk about ‘time’ it is often unclear which ‘time’ we are talking about. For the record, there are two different types of time:
- Cosmic time. This is what Stephen Hawking refers to when he speaks of the distorting effect gravitational masses such as black holes can have on time, and how time is actually a dimension -- along with space -- that came into being with the Big Bang.
- ‘Our’ synchronised time. This is the time we are all familiar with. The 60-minute hour; and 60-second minute. The 24-hour day.
If the first definition is confusing, don’t worry. The monks of late-thirteenth century did not require knowledge of black holes to construct the very first mechanical clocks. What we are focused on today is the concept -- and what everyone really means -- of ‘our’ time. It’s a whole different ball game.
The concept of synchronised time
The function of a clock is very simple: it counts the movements of oscillator and displays these oscillations in a tally (the time).
All an oscillator is, is something that makes a signal as it oscillates (moves) from a starting position to an end position. You might be familiar with a type of oscillator already: a pendulum. A pendulum is a fixed mass at the end of a rigid rod. Start a pendulum off swinging and it will eventually run out of steam -- air resistance will start to slow it down -- but the time it will take for a pendulum to move on a small angle and return to its starting point always runs to the exact same beat. This constant regularity is what makes the pendulum the ideal oscillator for a clock.
The earliest types of clocks strived for regularity, but did not have oscillators. This meant that the idea was there, but the execution was lacking. For example, water clocks kept time by dripping water in a series of lines down the side of a container. Sand timers keep time by requiring gravity to force sand or some other granular material through a small hole. The sand timer was one of the main devices for timekeeping before the invention of the mechanical clock in the fourteenth century Europe.
Before the mechanical clock all timekeeping was a struggle for consistency and rhythmic regularity.
Finding time and place in the new world
The world has ended, and no method of time keeping has survived. How can anyone start from the ground up, and reinvent synchronised time? The answer lies in looking up at the Sun and the stars.
The ancients noticed crucial things about the movement of the Sun: that at certain times of day its movement cast short, long, and invisible shadows; that at certain times of the year it stuck around in the sky, higher and for longer; bringing long and warm days. Then at other times of the year it seemed lazy, and the weather was cold, and it did not stick about for long. The ancients also noticed that only one star in the sky did not move in a circle -- Polaris, the North Star.
The Sundial and the Sand Timer
All of these observations were important in the first invention of a timekeeping device -- the sundial. To make a sundial, you will need something upright and straight; fixed permanently into the ground and a hemispheric shell in the shape of a circular arc with hour lines marked out in regular intervals. Creating a sundial is a relatively simple affair. One can be made with a flat circular sundial, but this will lose time around midday, when the shadows cast will be shorter and therefore ‘slower moving’.
It does not matter how many hours you mark out on the arc, as long as they are denoted at regular intervals. The concept of halving the day into two sets of 12 hour periods is something the ancient Babylonians did -- probably to honour the 12 constellations of the zodiac -- and not actually necessary.
The sundial is better than nothing, but imprecise 363 days of the year. Only on the spring and autumn equinoxes will the shadows move across the hour intervals all at the same time. These days can be calculated by observing the Sun as it rises at a perfect right-angle to the North Star. An equinox is when day and night are both exactly 12-hours; the word itself derives from Latin, meaning “equal night”.
It is these hourly intervals that will provide the most reliable measurements. All of today’s clocks work to what is known as the ‘standard equinoctial hour’. Presuming you want to mimic the Babyloninan convention of 24 hours split into two 12-hour periods, measuring the movement of the shadow on a sundial at the equinox will allow you to work out to the exact minute the ‘hour’ on which modern society is synchronized.
These measurements can be recorded with a sand timer, which in turn will come in handy later for gearing up (pun intended) the mechanical clock.
Re-building the mechanical clock
Congratulations, if you have already managed to precisely construct a sand timer that measures the standard equinoctial hour, then you have already leap-frogged thousands of years of human intuition. Now for the main event, the construction of a mechanical clock; a device that will enable universal, synchronised timekeeping among your fellow survivors.
The mechanical clock is a simple-at-heart but ingenious design. The earliest mechanical clocks weren’t clocks at all, but automated systems for ringing bells in monasteries to signal prayer (in fact the word ‘clock’ is derived from the Latin word for “bell”). Today’s clocks tick with a rhythmical beating not unlike a human heart. To make a mechanical clock, you will need four ingredients:
- A power source
- An oscillator
- A controller
- Clockwork gears
A power source does not mean reinventing the battery. As we know, the late-thirteenth and early-fourteenth century monks did not have that knowledge. What they used instead is very simple: a weight on the end of a string wrapped around a shaft. As gravity pulls on the weight, it tugs on the string, which turns the shaft -- generating power.
The best oscillator for reconstructing an early mechanical clock will be one we have discussed earlier -- the pendulum.
The problem with the power source is that, if left to its own devices, the weight will quickly unravel the string and that will be that. That’s where the controller comes in. The controller’s job is to regulate how the weight falls, and how it tugs on the string. A ‘controller’ is generally two things: a two-armed lever and a jagged-gear wheel connected to the pendulum.
The ingenious idea is in the design of the jagged-gear. It is designed to lock and disengage from the lever to the tune of the pendulum’s swing. As the pendulum swings to its beat, away from its starting position, this tugs the lever in the same direction with it and disengages the gear. This drops the weight on the string momentarily, which reinvigorates the pendulum so that it keeps swinging. The design is to trickle out stored energy, one tick at a time.
Standardising synchronized time
At this point, you will already have engineered the basic mechanical clock. The next step -- standardising the stepwise motion of the gears to the equinoctial hour -- is relatively easy. It would involve a mathematical function that would only allow the gears to make a full revolution every 12 hours. Once that is completed, then a minute hand can also be added to run stepwise with the gears, but at an aspect of 60:1.
This is all, of course, if you want to recapture the old Babylonian model of time-keeping. In the new world, things are up for grabs. For example, did you ever wonder why clockwise is the preferred direction for the hands of the clock? It is because the Europeans were accustomed to seeing the shadow of the sundial move across in a clockwise motion. If you are in Australia, or Brazil, or anywhere else in the southern hemisphere, it might make more sense for your new clock face to “follow the Sun” -- that is, in an anticlockwise fashion.
All clocks count oscillations, even the most advanced ones -- but they will be unobtainable for centuries, until much scientific advancement has happened. Electric clocks ‘count’ the oscillations of quartz crystals. Atomic clocks -- the most precise of all -- count the microwave oscillations of an element on the Periodic Table called Caesium. The rebirth of Chemistry will have to come about before these more precise, more rapid, clocks become a reality.
Cameron Dean is a science fiction writer and copywriter for Swiss Watch Trader. His post-apocalyptic novel, The Last Days of Summer, is on its third drafting.