An open question in mechanics of a spinning egg

It is surprising that a hard-boiled egg rises from the horizontal to the ver-tical when spun sufficiently rapidly on a table: the centre of mass rises against the gravity. This counter-intuitive motion is easy for everyone to observe in a kitchen without any special tool, but for a long time it had been remaining as a big challenge to be solved, while the flip-flop movement of a ”tippe-top ” was theoretically explained half a century ago. However, an outline explanation of this rising-egg phenomenon was proposed by Keith Moffatt and Yutaka Shimomura who is the author of the present paper. Their theory [1] provides a rare example of a system in which a dissipative force (here the force of slipping friction) is responsible for a visible instability. Later, Moffatt and Shimomura, together with Michal Branicki published a substantial paper [2], which provides detailed justification for the theory. Shimomura, Moffatt and Branicki published another paper [3] on this rising-egg phenomenon, which focuses on the fluctuating motions of the body