  A sudden change in the macroscopic parameters of a system will cause it to
depart from equilibrium. In this paper we study how a lack of change can also
inform of such a departure, and allow for work extraction. Potential events
that are unrealized can provide information pertaining the microstates of the
system, essentially playing the role of a passive Maxwell demon, thereby
allowing one to infer details about the microstate probability distribution.
Here, we first qualitatively argue that this effect is present and
consequential in almost every physical system, but is ignored in the standard
formulation of equilibrium statistical mechanics. Then, as a case study, we
quantitatively investigate the local and global thermodynamic properties of an
ideal gas placed in a fragile container that nevertheless, does not burst. This
non-event indicates a departure from equilibrium and allows work extraction
from the system. It also leads to corrections to the heat capacity of the gas.
