An equilibrium state is the most probable configuration in a thermodynamic system. It is a state of maximum disorder. Disorder is called entropy in thermodynamics, which describes a macroscopic system with large number of constituents (e.g., gaseous molecules) by some attributes such as pressure, temperature, heat, work, etc. Configuration refers to the arrangement of these constituents.
The following sequence of pictures illustrates the consequence when, the force (holding up the buildings) is removed by the implosion - it tends to disintegrate into rubble (greater disorder).
This tendency toward greater disorder is called the second law of thermodynamics and can be used to define the "arrow of time" since the sequence of events always flows one way to greater disorder. It is highly improbable for the reverse to happen naturally.