  Phase transitions abound in nature and society, and, from species extinction
to stock market collapse, their prediction is of widespread importance. In
earlier work we showed that Global Transfer Entropy, a general measure of
information flow, was found to peak away from the transition on the disordered
side for the Ising model, a canonical second-order transition. Here we show
that (a) global transfer entropy also peaks on the disordered side of the
transition of finite first-order transitions, i.e., those which have finite
latent heat and no correlation length divergence, such as ecology dynamics on
coral reefs, and (b) analysis of information flow across state boundaries
unifies both transition orders. We obtain the first information-theoretic
result for the high-order Potts model and the first demonstration of early
warning of a first-order transition. The unexpected earlier finding that global
transfer entropy peaks on the disordered side of a transition is also found for
finite first-order systems, albeit not in the thermodynamic limit. By noting
that the interface length of clusters in each phase is the dominant region of
information flow, we unify the information theoretic behaviour of first and
second-order transitions.
