Cosmic-string evolution: A numerical simulation

A system of intercommuting cosmic strings is numerically evolved in a homogeneous radiation-dominated expanding universe. Further evidence for the existence of a ‘‘scaling’’ solution is presented, and results for the long-string energy density are given. Long strings exhibit significant small-scale structure—kinks and short-wavelength propagating modes. Net loop production is observed to be strongly peaked at scales considerably smaller than the horizon, and reasons for this severe fragmentation are briefly discussed. The new numerical techniques employed are also described.