ccovemaker :
Stable voltage at 0 watts....ummm interesting science.
Nothing special/interesting about it: a Lithium battery delivers ~3.6V/cell open-circuit voltage, a fresh alkaline battery delivers ~1.65V/cell, a lead-acid cell delivers ~2.35V, etc. Mains voltage is 115-120V regardless of whether or not you have anything other than your multimeter plugged in. Your PSU's 12V rails are expected to hold 12V regardless of whether or not you have anything plugged in, same for 3.3V and 5V outputs.
Voltages can exist without a load. Voltages and electrical fields are everywhere; even in the vacuum of space.
Electrical current (measured in Amperes) on the other hand does require some form of conductor and load to exist.