This is the result of assuming a coefficient of kinetic friction that is independent of the load. While it is certainly possible to include numerically an ad-hoc load-dependent coefficient of kinetic friction, this would be at the cost of simplicity and additional free param. eters. In this Letter, we have instead opted to capture the essential physics needed to elucidate the interleaved- phone book enigma, and we reveal the key dimensionless parameter a 2LLE of the problem. Experimental Methods