In our three-dimensional world, measuring time
remains one of the most perplexing pursuits. How humans
measure time has changed dramatically through the ages.
How do we measure time? There are many answers. We can
use the sun and the distant stars. We can use sand through a
funnel. We can use atomic elements. We can use an expensive
watch. Why do we measure time? That's a question for you to
Since the Sun stays still while the Earth rotates, the
position of the Sun overhead reveals the passage of time.
This basic concept makes the sundial work as a timepiece.
Ancient sundials were quite simple, telling only the
approximate time. Today, a modern sundial can tell time to
The natural world offers other constants that can
measure time. Each of these timepieces relies upon a
constant in nature, like the Earth's rotation or movement of
water, to record and measure the passage of time.