★★☆ Moderate

↔ Lorentz Contraction

A moving object appears shorter along its direction of motion by the Lorentz factor γ. Drag β toward 1 to see the ruler compress. A transverse ruler remains unchanged.

β = v/c = 0.00

Presets:

γ = 1.000 Rest length = 300 px Observed length = 300 px Contraction = 0.0%

L = L₀ / γ = L₀ √(1 − β²) | γ = 1/√(1−β²)

Lorentz–FitzGerald Contraction

Predicted independently by FitzGerald (1889) and Lorentz (1892) and explained by Einstein's Special Relativity (1905): any object moving at speed β = v/c is measured to be shorter in the direction of motion by the factor 1/γ. The rest length L₀ is what an observer at rest relative to the object measures. A moving observer measures the contracted length L = L₀/γ.

Only the dimension parallel to motion contracts. Transverse dimensions (height, depth) are unaffected — shown by the unchanged green bar. Near β = 0.99, γ ≈ 7, so the ruler is only ~14% of its rest length.