  We present observation of large, expanding string loops forming around a
heated wire tip embedded in a nematic liquid crystal sample. Loops expand due
to convective stretching. This observation leads to a new insight into
phenomena which could occur in the early universe. We show that local heating
of plasma in the early universe by evaporating primordial black holes can lead
to formation of large, expanding cosmic string loops, just as observed in the
liquid crystal experiment. Intercommutation of string loops from neighboring
black holes can lead to percolation, thereby forming an infinite string
network. This is remarkable as such an infinite string network is thought to
arise only when the entire universe undergoes phase transition.
