“…It appears that in the basic Skyrme model, the global minimum of the energy is attained in each sector C B , but there is no proof of this. Calculations suggest that it is not favourable for a Skyrme field of baryon number B to break up into infinitely-separated subclusters whose baryon numbers add up to B, but these calculations have loopholes [31,32]. The topology of the space of maps U : S 3 → S 3 is quite rich, so within each sector C B there are non-contractible loops and spheres of various dimensions, and as a result, there are numerous unstable solutions of the field equations, i.e.…”