Early humans ate only the food they caught and used only the tools they made. Millennia of effort to overcome the coupling of production and consumption eventually led to agriculture, mass manufacturing and electric power distribution. The resulting specialization of work, economies of scale and novel technologies define our modern world--and allow me to sit in a caf¿ sipping an espresso and writing this article on a laptop computer, with no thought to the ultimate sources of the water, coffee, electricity and wireless-network bandwidth that I consume.

The ready availability of these resources exemplifies the concept of virtualization, which (to computer scientists) refers to hiding useful functions behind an interface that conceals the details of how they are implemented. When the caf¿'s barista, for example, turns on a water spigot, it is as if he taps a bottomless barrel. The same phenomenon occurs when I plug my laptop into a wall socket. Given the huge unseen electric grid beyond the plug, who knows how and where that power was generated?

   
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