The capabilities of the human mind never cease to amaze me. And, sometimes my own mind and its ability to remember things from long ago surprises me. On my recent trip to the Houston Museum of Natural Science we stopped for a few minutes to watch the Foucault pendulum. The pendulum swung back and forth, moving evenly around the circle, knocking over two of the domino like markers every 15 minutes. Back and forth, back and forth. Even as we stood there watching I had the thought, way in the back of my mind, that this was not the first time I had watched a pendulum moving around a circle.
I was full of questions about how this thing worked. My nephew, the engineering student, patiently explained how it worked and answered my questions. I understood that the pendulum was fixed and it was really the rotation of the earth that was giving the appearance of movement. But I couldn’t grasp what was keeping it moving so evenly. Yet, I still kept thinking, “I know all of this, I’ve seen this before” somewhere deep in my thoughts. We waited for it to knock over two markers and we moved on to other exhibits.
After we got home I did my homework (which I should have done before the trip) and discovered that there is a magnet surrounding the cable at its top. As the pendulum reaches the middle of its swing, it closes a circuit that activates the electromagnet and pulls the cable away from the center position. At Houston’s latitude (30° N.) the pendulum will move halfway around each day and knock down all of the pins.
As I was reading about this pendulum and Leon Foucault, the inventor, the thought that I’ve seen this before became stronger. I kept putting it in the Griffith Observatory that I had visited as a sixth grader on a Girl Scout field trip. After a little internet searching I found what my memory was telling me – there was a Foucault pendulum there and it was exactly as I remembered it!
The fact that I could remember this long ago event was entertaining, but what made me laugh was remembering my thoughts that day that all that science stuff didn’t make any sense to me. The planetarium enchanted me because I liked astronomy (still do), but the rest was lost on me. But, maybe not. I think my brain stored up all that data for me to pull out one day when something in my memory triggered it!
The Foucault pendulum is amazing and so is the human brain. The song Somewhere In My Memory from the Home Alone movies keeps playing in my mind!