5.07 · Waiting for a Drop of Pitch

Waiting for a Drop of Pitch

At first glance, pitch looks like a solid. It is black and hard, and it breaks into pieces if you hit it with a hammer. But pitch is really a liquid, and it flows very slowly.

In 1944, physicists at Trinity College Dublin set up a simple experiment: a funnel full of pitch, with a beaker underneath. A drop falls only about once in ten years, so for decades nobody watched it. Dust covered the equipment, and drops fell without anyone seeing them. The experiment needs only pitch, gravity and time.

In 2013, that changed. In April, the physicists saw that another drop was forming, so they moved the equipment and put a camera in front of it. From May, anyone could watch it live on the internet. In the late afternoon of July 11, a heavy, tear-shaped drop finally fell. That was the first time anyone had recorded a pitch drop falling.

After sixty-nine years, the wait to see a drop fall was over. A good result needed patience, a camera, and someone who was ready to watch. Today the experiment keeps running, and this time someone is watching it.