Of Naturalness and Complexity

Abstract: It is argued that the occurrence of disproportionately ("un-natural") large (or small) numbers, as well as deep cancellations, are comparatively natural traits of the way Nature is geared to operate in most complex systems. The idea is illustrated by means of two outstanding and over-resilient problems in theoretical physics: fluid turbulence and the computation of ground-states of quantum many-body fermion systems. Potential connections with the issue of Naturalness, or lack thereof, in high-energy physics are sketched out.