1. A method for applying RF energy to determine a processing state of an object placed in a cavity, during processing of the object, the method comprising: applying RF energy to the object during the processing; receiving RF feedback indicative of a dielectric response of the cavity and/or the object to electromagnetic (EM) fields excited in the cavity; mathematically manipulating RF feedback to obtain computed RF feedback, correlated with one or more processing states of the object; and monitoring the computed RF feedback during the processing to determine the one or more processing states of the object.