Spacetime Diagram: The Pole in the Barn
The classic pole-in-the-barn scenario:
A runner carrying a pole runs through a barn at extremely high speed (here 3/5 the speed of light). The pole and the barn have the same rest lengths.
The velocities of pole and barn, and of the observer from whose reference frame the diagram is constructed, are shown (all as measured from the earth's frame).
Drag the slider to change the observer's frame.
Four events are labeled:
A: The left door of the barn opens just as the right end of the pole reaches it.
B: The left door of the barn closes just as the left end of the pole clears it.
C: The right door of the barn opens just as the right end of the pole reaches it.
D: The right door of the barn closes just as the left end of the pole clears it.