Thermodynamic energy exchange in a moving plate capacitor

In this paper we describe an apparent paradox concerning a moving plate cap acitor driven by thermal noise from a resistor. The plates are attracted to gether, but a demon restores the plates of the capacitor to their original position when the voltage across the capacitor is small-hence only small fo rces are present for the demon to work against. The demon has to work harde r than this to avoid the situation of perpetual motion, but the open questi on is how? This is unsolved, however we explore the concept of a moving pla te capacitor by examining the case where it is still excited by thermal noi se, but where the restoring force on the capacitor plates is provided by a simple spring rather than some unknown demon. We display simulation results with interesting behavior, particularly where the capacitor plates collide with each other. (C) 2001 American Institute of Physics.