the occasionally awesome James May on TV this week explained semi-conductors by olding up a spoon (conductor) and a copy of a vinyl record in cardboard record cover of Jeff Wayne's Musical Version of The War of the Worlds (insulator)
this made me think of alternative crazy types of gate that one might propose
historical battles (marathon, poitiers 1&2 etc) aer really gating functions to either populations or cultures moving from one area to another - think of the movement as a large current, and the small armies (relatively speaking ) as a voltage applied - i.e. valve/transistor/switch/gate...
so the whole of history of human migration and population plus landmark battles could be viewed as a computation....what does it compute tho? 42? 23? or does it just deliver a ring pull from a coke can to a stranded tralfamadorian on Titan?