UC Berkeley Berkeley Scientific Journal

Title The Mechanics of Timekeeping

Permalink https://escholarship.org/uc/item/7fs3p0sj

Journal Berkeley Scientific Journal, 21(1)

ISSN 1097-0967

Author Liu, Katherine

Publication Date 2016

DOI 10.5070/BS3211033747

Undergraduate

eScholarship.org Powered by the California Digital Library University of California THE MECHANICS OF TIMEKEEPING

BY KATHERINE LIU

THE DEVELOPMENT AND MECHANICS OF MEASURING TIME IN HUMAN HISTORY

by all major cultures, works by indicating melted down and the height of the candle ince the earliest human civilizations, the time of day by the length and direction at diferent moments measure how much S 1 humans have kept time in one form or of a shadow cast by the sun’s light. But time has passed. another, either through water clocks, because such devices cannot work at night, More modern forms of timekeeping sundials, hourglasses or candle clocks. the sundial’s counterpart, the water clock, include pendulums, pocket watches, and Tough primitive, these early forms of was created to tell time during the night. classroom clocks. Tese are still relatively clocks were the building blocks of modern Te water clock is a basin of water that lets simple compared to today’s digital clocks timekeeping technology. However, even water drip from a small hole near the base and beyond, but are equally interesting and though time is such an essential part of our of the basin. Lines were drawn inside the important. Pendulums are quite distin- lives, many people do not understand the basin walls to denote sections of time so as guished in function from clocks and pock- mechanics underlying clock function. the water level dropped, it would gradually et watches in that they don’t have as many Archaeological evidence has shown that reveal lines above the water level, thereby small components that aid it in telling the Egyptians and Babylonians began indicating the time.1 time. Te main parts of a pendulum are measuring time 5,000 years ago. Tey Te earliest clocks, along with the sundial the rod and weight which together swing started by recording the length of a day and water clock, are the hourglass and side to side in an oscillating motion.2 To by following the sun across the sky and candle clocks. We ofen see these in flms maintain the same oscillating rate, there noting the phases of the moon.1 Te and animation to give an archaic setting. are specifc confgurations not seen from Egyptians also created calendars that However, even these seemingly familiar the outside. But this does not prevent a had 12 months with 30 days each. Tese and simplistic clocks are quite impressive pendulum clock from eventually lagging in calendars even included 5 extra days every in being able to accurately keep time even timekeeping. So, occasionally, a clockmak- year to estimate the solar year. Te next before the physics regarding water fow er or clock owner will need to reconfgure form of time measurement came with and planetary motion were understood. the cogs in a pendulum so they read time the invention of the sundial. Te sundial, Te candle clock works similarly to the accurately. Pocket watches and clocks are which has been invented independently water clock in that the wax of a candle is unique from pendulums. Clock mechanics

44 Berkeley Scientifc Journal | FALL 2016 “Time is a way to track the irrevers- ible occurrences in our lives, from deaths, to food eaten, to water spilled”

atomic clock in that instead of using atoms of an element, it uses single ions to absorb the radiation and record the frequency and subsequently tick of seconds based on this are interesting in that there are many capement. Tis escapement has mostly the frequency of registered ions.3 diferent confgurations, called escape- same confguration as the Verge Escape- It is important to think about how these ments, of clock pieces. Tese escape- ment, only all the wheels and pallets are devices impact how we perceive time. ments have diferent efciencies, energy put on their side: it runs horizontally. Te Time to most people is a common occur- conversion, and accuracy.6 Several name of this escapement hints at the image rence that has no special meaning other such escapements worth noting are the of the escapement: the pallet position and than the fact that it is how we run our daily Verge Escapement, and the Grasshop- motion in relation to the escape wheel lives. What many people haven’t thought per Escapement.2 looks like the leg of a grasshopper as well about is that time is mostly just imagined. Te Verge Escapement is likely the old- as the coupling rods on a train, connecting Aristotle once described time to be a mea- est clock escapement and consists of a the wheels and rotating in place.2 sure or number of some sort of motion. crown-shaped wheel (the escape wheel) All of these diferent clock escapements Tis means that time is not an indepen- that turns vertically with its ‘teeth’ will eventually require repair because over dent entity and cannot exist separate from protruding to one side. Tese teeth time, their efciency decreases. With so other things in the world.4 Time is directly push a pallet (a rod with parts that can many small metal parts pushing against related to the objects in our lives and is be pushed by the crown-wheel’s teeth) each other, friction is inevitable, which is solely there to measure the motion of those causing the pallet’s rod (the verge) the main source of energy inefciency in objects. Tis notion takes time to digest, to rotate in a single direction. As the clocks.6 but fundamentally greatly makes sense. crown-wheel continues to rotate, it More modern forms of timekeeping and Time is a way to track the irreversible oc- pushes the pallet into completing many clock mechanics include the atomic clock currences in our lives, from deaths, to food cycles, and each cycle translates into and quantum clocks. Previously described eaten, to water spilled. But this then asks a small movement of the hands on a clocks and timekeeping devices relied on the question: why do we bother to measure clock moving clockwise.2 physical characteristics to read time. But time to intricately using high-tech clocks many clocks such as the atomic and quan- and other precise machines if time isn’t tum clocks, use ions, atoms, and radiation ‘really’ there? And though there is no clear waves that are not visible to precisely answer, and is subject to personal views, a measure time. good reason shared by most people is that Inside an atomic clock, atoms of speci- time creates a sense of order in society and fed element, such as cesium, are pushed daily life. If we didn’t have a schedule to through a tube to an area where they are follow, people would just wander aimless- exposed to radio waves of a specifed fre- ly all day long. Tey wouldn’t value their quency. Te energy from these radio waves lives because they wouldn’t realize that it cause the cesium atoms to resonate and was passing so quickly. Days would melt change their energy state. A cesium together and we would never have a sense detector at the the end of the tube registers of purpose if we didn’t keep time. every time a cesium atom reaches it, and will tick of a second of time once a certain frequency of cesium atoms striking the Similar yet diferent from the Verge detector is met.5 Escapement is the Grasshopper Es- A quantum clock is a specialized type of

FALL 2016 | Berkeley Scientifc Journal 45 Atomic clock in a laboratory

Watch Escapement Mechanics. 1-87. Re- References trieved October 3, 2016, from http://www. 1. Andrewes, W. J. (2006, February 1). nawcc-index.net/Articles/Headrick-Esc- A Chronicle Of Timekeeping. Retrieved Mechanics.pdf October 10, 2016, from https://www. scientifcamerican.com/article/a-chroni- Image Sources cle-of-timekeeping-2006-02/ Banner Image: http://cdn.wonder- 2. Du, R., & Xie, L. (2012). A Brief Review fulengineering.com/wp-content/up- of the Mechanics of Watch and Clock. His- loads/2014/10/time-wallpaper.jpeg tory of Mechanism and Machine Science Sundial Image: https://images.roberthard- Te Mechanics of Mechanical Watches ing.com/preview/RM/RH/HORIZON- and Clocks, 5-45. doi:10.1007/978-3-642- TAL/206-768.jpg 29308-5_2 Verge Escapement Image: https://blog. 3. Erker, P., Mitchison, M. T., Silva, R., klockit.com/2015/05/27/making-time-the- Woods, M. P., Brunner, N., & Huber, M. great-escapement/ (n.d.). Autonomous quantum clocks: Atomic Clock Image: http://www.urania. How thermodynamics limits our ability to be/sites/default/fles/Tijd%20en%20secon- measure time. Retrieved October 10, 2016, den%20huidige%20atoomklok from https://arxiv.org/pdf/1609.06704v1. %20atomuhr%20FOCS%201.png pdf. 4. Gale, R. M. (1967). Te philosophy of time: A collection of essays. Garden City, NY: Anchor Books. Retrieved October 28, 2016, from https://books.google.com/ books?hl=en&lr=&id=rWChCwAAQ- BAJ&oi=fnd&pg=PA1&dq=philosophy of time&ots=2jU1n9LCw8&sig=M6cvk- d4up4vmTgCpfG7e27kC-A#v=onep- age&q&f=false. 5. Gessner, W. (2015, November). Ideal Quantum Clocks and Operator Time. Retrieved October 10, 2016, from https:// arxiv.org/fp/arxiv/papers/1305/1305.0949. pdf. 6. Headrick, M. V. (1997). Clock and

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