  Statistical physics provides a useful perspective for the analysis of many
complex systems; it allows us to relate microscopic fluctuations to macroscopic
observations. Developmental biology, but also cell biology more generally, are
examples where apparently robust behaviour emerges from highly complex and
stochastic sub-cellular processes. Here we attempt to make connections between
different theoretical perspectives to gain qualitative insights into the types
of cell-fate decision making processes that are at the heart of stem cell and
developmental biology. We discuss both dynamical systems as well as statistical
mechanics perspectives on the classical Waddington or epigenetic landscape. We
find that non-equilibrium approaches are required to overcome some of the
shortcomings of classical equilibrium statistical thermodynamics or statistical
mechanics in order to shed light on biological processes, which, almost by
definition, are typically far from equilibrium.
