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After Decades of Waiting, Scientists Finally Observe Pitch Drop

Jul 19, 2013 04:55 PM EDT

It might seem like a minor thing -- a piece of pitch forming a drop that subsequently separates -- but scientists have been waiting patiently for decades to watch this phenomenon that, despite taking anywhere from seven to 13 years to build up to, occurs in a tenth of a second.

This particular experiment was first set up in 1944 at Trinity College Dublin in order to demonstrate the viscosity, or fluidity, of pitch, which is also known as asphalt or bitumen. But another, located at the University of Queensland in Australia, first began in 1927 in one teacher's effort to prove to his students that things are not always what they seem.

This is because pitch is hard and rock-like; in fact, if struck with a hammer, it will shatter. However, by definition it is flowing, only at very slow speeds: all told, pitch is 2 million times viscous than honey and 20 billion times more so than water.

Despite representing the longest-running laboratory experiment in the world, according to Guinness World Records, and despite there being two of these experiments, it wasn't until July 11 that the moment in which a drop of the substance separates was seen by human eyes.

John Mainstone, who has overseen the Queensland project since 1961, described to WNYC's Radiolab back in February the frustration behind his missing this drop time after time.

After missing it in 1962 and then 1970, he said he was so eager to be there the moment it fell that, in 1979 when it appeared to be nearing its point of breaking away, he decided to come in over the weekend to check on it.

Saturday night nothing had happened. Monday morning the drop of pitch lay on the surface where it had fallen.

Around 1988 another drop was getting ready to fall when Mainstone stepped out the room just for a moment -- maybe to get a cup of tea -- and, much to his dismay, missed the drop by perhaps as little as 15 minutes.

With the advent of the technology and determined to never again miss the crucial moment, he installed a camera. The year 2000 came, the pitch fell while Mainstone was out of town and, as fate would have it, the camera failed.

"That was one of my saddest moments, I must say," he told Radiolab.

Mainstone subsequently installed not one but two more cameras and, 13 years later, was once again patiently awaiting the drop when the news came -- other researchers had caught the phenomenon on camera, meaning whatever Mainstone records going forward will no longer represent the first in scientific discovery.

What exactly are scientists like Mainstone looking for out of the experiment?

According to those involved, without seeing it, it's not clear how the pitch separates, including details such as what breaks first. Now, however, with the video online, anyone can observe and take their own notes -- including Mainstone.

"I have been examining the video over and over again," he told Nature, "and there were a number of things about it that were really quite tantalizing for a very long time pitch-drop observer like myself."

And then, says Denis Weaire of Trinity College Dublin, there's a different kind of value that such an experiment brings that can't be rehearsed in studies published in prestigious journals.

"Curiosity is at the heart of good science," he told Nature, "and the pitch drop fuels that curiosity."

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