What are clocks?

A clock is an instrument that is used to measure time. Ancient clocks such as sundials used the position of the Sun and shadows to keep track of the time. Instead of offering a precise time, though, sundials provided a general sense of the time of day based on the position of the Sun. Modern clocks, on the other hand, aim to precisely measure the time between two events that recur at constant intervals.

• Discuss how clocks work generally (measuring time between two events)
• Describe the different types of clocks and how they work (include diagrams)
• Explain what makes a clock ‘good’

Why does precision matter?

• For everyday things, clocks don’t have to be ultra precise. As long as the time is correct within a few minutes, there is little consequence if your clock is off from the actual time.
• Precision does matter when thinking about:
  • Communications: Super precise clocks use synchronized fiber optic switches that connect devices together, and cellphone towers
  • Navigation and GPS: measure the timing of signals and to report positions relative to satellites using triangulation
  • Science: Measuring physical phenomena like gravitational waves requires incredible precision. Atomic clocks allow scientists to make super precise measurements and do fundamental tests of the theory of General Relativity.

What affects a clock’s precision?

• The power source – most clocks use batteries to send an electrical pulse to the quartz vibrator. Over time, the battery power (and therefore the strength of the pulse) decreases, leading to a decrease in the clock’s precision.
• Environmental variables, such as temperature
• When moving really fast or near something really massive (aka relativistic effects). This more changes how time is moving as opposed to the clock’s precision

What makes an atomic clock special?

Atomic clocks are the most precise clocks in existence. They use the special properties of atoms, namely that all atoms have discrete, well-defined electron transitions, as their definition of a second.