Spacetime Diagrams

Drawing motion through time

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

• Spacetime diagrams plot time up and space across; points are events.
• With years and light-years, light travels at 45°.
• Slower-than-light worldlines are steeper than 45°.

Steps

1. Time goes up
2. Worldlines
3. Reading a worldline
4. A moving observer’s axes
5. Reading the rocket’s clock
6. The tilted line