Physics And Cities: View From The Street : 13.7: Cosmos And Culture Cities are defined, in large part, by physics. It may not be obvious at first glance. But look closer and you'll see evidence everywhere that humans have used their understanding of physics to design and build the machines we call cities.

Physics And Cities: View From The Street

Physics And Cities: View From The Street

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Canal Street in New Orleans Mario Tama/Getty Images hide caption

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Mario Tama/Getty Images

Canal Street in New Orleans

Mario Tama/Getty Images

I was born and raised in the vast urban ecology that is the New York region's metropolitan jungle. As a young man my love for the city and my love for physics grew together. Now I am old enough to see that the pairing of those two romances was no accident.

Beginning this week I will be exploring the relationship between physics and cities. It's part of NPR's most excellent project on Cities. The questions I want to explore concern both the physics of cities and cities as examples of physics.

To tackle these questions, we decided to look at cities on three different scales: from the street, from the roof top and from space. Each scale teaches us something different about how physics shapes the form and function of a city.

We start with city streets, which may just be the best physics lab ever.

For a physicist the world is a theater of forces and energy. Untangling the way forces and energy work in the natural world can be complicated. But cities are, by design, lots of straight lines and right angles. They were built out of an understanding of physics.

Where do you find street-level physics? Everywhere. The lurch of a subway car will teach you more about Newton's laws then a thousand textbooks. Want to experience a (seemingly) variable force of gravity? Step into an elevator and feel it accelerate.

Cities exist to turn energy into useful work. They are machines, engines of the human endeavor. Just look a the plumbing!

On the street you can see evidence of all the many channels bringing energy into the city, and managing its flow. Steam rising from manhole covers speaks of heat flushing through hidden arteries. Subway gratings speak of vast systems of circulating air drawn into the underground and back again. Streetlights hint of power lines snaking beneath the street and transformers buzzing in basements.

Everywhere you look on the street you see the dance of energy flowing in its many different forms: motion, current, heat and light. That glorious choreography is nothing less than a collaboration between our human genius and the natural laws that govern our universe.

You can keep up with more of what Adam Frank is thinking on Facebook and on Twitter @AdamFrank4. His latest book is About Time: Cosmology and Culture at the Twilight of the Big Bang.