In this hour of Radiolab, we take to the street to ask what makes cities tick.

There's no scientific metric for measuring a city's personality. But step out on the sidewalk, and you can see and feel it. Two physicists explain one tidy mathematical formula that they believe holds the key to what drives a city. Yet math can't explain most of the human-scale details that make urban life unique. So we head out in search of what the numbers miss, and meet a reluctant city dweller, a man who's walked 700 feet below Manhattan, and a once-thriving community that's slipping away.

***It's Alive? There's no scientific metric for measuring a city's personality. But hit the streets, and you can see and feel it.

***The Belly of the Beast

***Dying Embers. An underground fire sweeps through a town, and changes everything.

[October 7, 2010]