Kate Gramling Principal consultant Illumineer

Engineering Time

PostedTuesday, November 5, 2019 at 9:12 PM

Engineering Time

Time. Enemy or friend, it marches on without concern for the humans on this planet. I’ve been thinking a lot about time this week, because, of course, we returned to standard time in Sunday’s wee hours.

I grew up on a farm in a state that didn’t observe Daylight Saving Time until recently, so I still find the whole idea … annoying. Very little of my schedule now has anything to do with daylight, so the semi-annual reminder of how much clocks control daily life is irksome.

Clocks tell us when to go to work and when to come home. They countdown to deadlines and tick away the time spent waiting in line or traffic. Clocks are oblivious to sunlight.

Sunlight is a natural phenomenon, but time, for all practical purposes, is a quality defined by its measurement. It’s easy to think of time as a natural force, like gravity, but as Einstein tells us, “time is an illusion.”

SundialFor the bulk of human history, time has been measured by observations of the natural world. Our earliest ancestors would count days by the appearance of the sun in the sky. When that wasn’t enough, they developed sundials to count the daylight hours. When that wasn’t enough, they developed other tools, like water clocks, which could measure the passage of time at night.

As civilizations spread and technology became more complex, our need for precise and reliable measurement of time increased. We specified time standards, created time zones, and built portable timepieces. The technology of timekeeping, in turn, helped speed up the pace of discovery and commerce.

We’re now a long way from sundials and water clocks. Today, we define a second using the frequency of vibration in the hyperfine ground state of caesium-133 atoms. The caesium fountain clock, based on this, is so precise that physicists say it will neither gain or lose a second in more than 100 million years.

It is difficult to talk about time without considering the technology used to measure it. That makes it a topic that naturally brings together history, mathematics, engineering, and science. There are lots of ways to investigate time that encourage engineering discussions and activities. For example:

  • Investigate devices used to tell time. How have they changed through history and what other forces or technologies helped contribute to their development? What are the strengths and weaknesses of each design?
  • Designing Harmonic Timing Devices: Ready, Set, Escape
    In this activity, students are asked to design simple yet accurate timing devices using limited supplies. The challenge is to create a device that measures out a time period of exactly three minutes in order to enable a hypothetical prison escape.
  • Portable Sundial
    Students investigate the accuracy of sundials and the discrepancy that lies between "real time" and "clock time."
  • How would our lives be different if we did not have any tools that measure time? Or if we had only sundials or water clocks or hourglasses?

Pocket watch photo by Debbie Schiel; Sundial image by Jolene00; both found on


Filed Under Earth & Space Sciences Physics/Physical sciences Engineering