Having experience with three children now, I would like to put forward some theorems on the physics of pacifiers (pacis, binkies, etc.). These are all based on my observations.
Theorem of Paci Uncertainty: It is not possible to know the location of all pacis designated for a single child at any given point in time.
Theorem of Paci Induced Equilibrium: It is necessary to know the location of at least one paci at any given time in order to sustain equilibrium. If no pacis have a current known location, one must be located in order to ensure equilibrium can be achieved.
Theorem of the Paci Property of Substitution: When the location of one paci becomes unknown, the location of that paci will not again be known until another paci has been located first.
Theorem of States of the Paci: A paci may exist in a continuum of subjective states of cleanliness, which are only able to be evaluated by the observer (parent). The state determines whether the paci is suitable to use to restore equilibrium. Some factors affecting the evaluation of the state of the paci include experience of the observer, gender of the observer, subjective evaluation of the cleanliness state of the location where the paci has fallen, application of the "three second rule," average hours of sleep the observer has experienced that week, and how far away the system is from equilibrium.
I hope these thoughts help parents pursue further study regarding the paci.