crossman said:
anything that can be described as a variable resistance is a variable resistance.
Your model of a voltage sensing servo motor twisting the armature of a potentiometer, while producing the same circuit effects, relies on:
- large construction (fractions of inches or larger - macro scale),
- conversion of electromagnetic energy to mechanical motion and then mechanical motion back to electromagnetic energy,
- high power consumption to vary the resistor.
As the Spectrum article states, that solution to the theoretical concept was dismissed as a dalliance, that is, as possible, but of limited practical value. The article also implies there were other solutions to the principle of memristance than em - mech - em which were also dismissed.
The new breakthrough from Hewlett Packard's Stanley Williams, et. al., is that at micro levels small enough that quantum physics plays an important role, a single solid state construction of titanium dioxide + dopants exhibits the memristance properties predicted almost forty years ago by Leon Chua. This is exciting because it apparently fits very well into the world of integrated circuits, which a servo - pot would not.
What holds my attention is the symmetry of the relationships of charge, current, voltage and flux that occurs when the principle of memristance is included in the diagram in the Spectrum article (the second image).
The rules of resistance, inductance and capacitance are not to be re-written, only added to, and the addition is memristance.