A Physicist's View of the City as Machine

Frank, who wrote recently for NPR on the physics of cities visible at street-level, returns to the subject from a higher perspective. From a roof-level view, he explains how cities exhibit the Second Law of Thermodynamics, which states that, "Useful work creates unusable waste [or entropy], always and forever." 

What strikes Frank from the rooftop is not what he sees, but what he can hear. "There is a word that applies to the sound of cities which almost never gets applied to nature: 'Din.' The din of cities heard on the rooftop as a rising wall of noise is a testament to the true nature of cities as engines of organization and dynamos of disorder."

The dark side of this beauty, however, writes Frank, is that "the work we do to create and maintain cities means we are also raising the level of disorder, waste and pollution for the planet as a whole."

"We live at a moment when cities are poised to become the dominant mode of human habitation on the planet. But we don't yet know if such a mode can be made sustainable for more than a century or two. Coming to grips with that question can only mean coming to understand the physics of cities - the physics of thermodynamics and its ever-present second law."