This situation is similar to a body exactly balanced at the top of a smooth surface that, with the slightest disturbance will depart from its equilibrium position and continue until it reaches a local minimum. As they are described such states are dynamically unstable, and consequently they are not observed. The gap v m i n ≤ ≤ v ≤ ≤ v m a x is a precursor of the actual phase change from liquid to vapor. The points E ( p m i n , v m i n ) and C ( p m a x , v m a x ) , where ∂ ∂ v p | T = 0 , that delimit the largest possible liquid and smallest possible vapor states are called spinodal points. Their locus forms a spinodal curve which bounds a region where no homogeneous stable states can exist.