  In weakest link models the failure of a single microscopic element of a
brittle material causes the failure of an entire macroscopic specimen, just as
a chain fails if one link fails. Pristine samples of glass, such as optical
communications fiber, approach their ideal strength, and their brittle tensile
failure has been described by this model. The statistics of weakest link models
are calculable in terms of the statistics of the individual links, which,
unfortunately, are poorly known. Use of the skewness of the failure
distribution may permit simultaneous determination of the statistics of the
individual weak links and of their number density, which indicates their
physical origin. However, the applicability of weakest link models to real
materials remains unproven.
