Why Do Raw Eggs Wobble?

The shell gives both eggs the same outline. The inside gives each egg a different spin.

When a hard-boiled egg rotates, the solid white and yolk move with the shell, so the egg stays balanced and spins smoothly. A raw egg contains fluid. The shell can move ahead of that fluid, which shifts the balance point and damps the rotation. A brief stop makes the effect easy to see: the raw egg can start moving again because the liquid inside still has motion.

Science World and the Exploratorium describe the stop-and-release test, and a Dartmouth physics demonstration records the raw egg's rapid damping. 123

The real egg photograph is Pexels photo 7118759.