Moving Clocks Run Slow

The light clock

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Moving clocks run slow: $t = \gamma t_0$, where $\gamma = 1/\sqrt{1 - v^2/c^2}$.
• The light clock shows why: the same speed of light along a longer path means a longer tick.
• Confirmed by muons, atomic clocks on aeroplanes, and GPS.

Steps

1. The light clock
2. The time dilation formula
3. Compute γ
4. Space trip
5. GPS clocks
6. Muons