Shrinking Rulers

Length contraction

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 objects contract along their direction of motion: $L = L_0/\gamma$.
• Time dilation in one frame is length contraction in another, and both agree on what happens.
• Neither frame is “right”: lengths and times depend on the observer.

Steps

1. The muon’s view
2. Length contraction
3. Moving spaceship
4. Half the length
5. A cosmic ray’s galaxy
6. Who’s right?