You guys. YOU GUYS. HOLY CRAP YOU GUYS IT FINALLY HAPPENED. After decades of observation, the climax of one of the longest running experiments in history has finally been captured on video. The pitch! It has dropped!
Tar pitch is the material used to coat roofs and pave roads. If you hit it with a hammer, it shatters like a solid. But it's actually a liquid. It even flows like a liquid. It just does it very, very, very slowly.
In 1944, physicists at Trinity College Dublin set up an experiment to demonstrate that, firm and stable appearances aside, tar pitch is, in fact, a liquid. The pitch-drop experiment was born.
Pitch drop experiments are all about time and patience. To prepare one, you start by heating a sample of pitch and pouring it into a sealed glass funnel. Then, before you even begin the experiment, you need to give the pitch a few years to cool to room temperature. When you're sure the pitch has cooled, cutting the tip of the funnel allows the pitch to flow at its own, mindnumbingly slow pace. Since 1944, the drips of pitch have come at a rate of about once per decade, but never before has a drop been captured on film or video. Back in 2000, the drip from an even longer-running pitch-drop experiment in Queensland, Australia was missed due to technical difficulties. But this time – THIS TIME – scientists were ready. And on July 11, 2013, around 5 in the afternoon, a drop of pitch was captured breaking away from the descending flow.
According to Nature, the Trinity College team has estimated the viscosity of the pitch "in the region of 2 million times more viscous than honey, or 20-billion times the viscosity of water." The Queensland experiment has calculated the viscosity of its pitch to be 100-billion times that of water. Point being: pitch is one viscous liquid.