- 2017 IEEE. In this talk, we are briefly surveying our recent results  challenging the claim that the memristor is the "Missing circuit element" . The crucial question is if the memristor equations guarantee that the device can be realized by passive components. With active components and feedback, arbitrary device characteristics can be realized. Recent work of Chua indicates  that certain type of memristor features may imply an active device. Our "thermal noise test" shows that there are infinitely many situations where the physical realization of memristor equations requires an active device. Therefore the memristor equations, in their present form, do not provide the "Missing circuit element" as an innately passive device. Traditional resistors, inductors and capacitors defined by the Maxwell's equations remain the fundamental, reliably passive building elements of electronic circuitry.