Swings in Harlem

(the editing over at AAAS is getting rather heavy handed, but I will try to learn to stick to a single idea and to use simpler sentences...)

My daughter’s childhood was spent in the little-kid wonderland that is Upper Manhattan.  Playgrounds abound and there is never a dull moment when one is out and about.  As we would swing together in the Downstairs Playground, I pondered the nature of our swinging.  In particular, despite the fact that the chains on our respective swings were the same length, the period of our swinging was different.  Similarly, when kids flung the swings without a body in them, they didn’t exhibit the wonderful behavior of the introductory physics lab.  What was going on?

The simple answer is that we were in a playground in Harlem.  In Harlem, the pendulum’s “massless rod” has mass and displacements are not necessarily small.  All of those messy terms related to mass and displacement don’t go to zero and the nice oscillatory solution of the lab gets swallowed up in a jumble of vandalism prevention and youthful exuberance.

Just as my thinking about swings in Harlem reminded me of forgotten assumptions, much of my thinking lately about “sustainability” has to do with the often-unstated values that are imbedded in its use.  “Sustainable” usually has implications of conservation and efficiency, while “sustainability” usually spans a larger domain that also includes notions of “social justice.”

I think that it is important not to forget what we mean when we say “sustainable”; even more, I think that it is important that we continue to reflect on those underlying meanings and their associated values.  Physics in Harlem is going to remain fairly constant over the coming centuries, but I expect that values there will evolve.  And while swinging may be universal, what Dad does while it is happening can reflect important regional differences in today’s value systems.