Researchers at Trinity College Dublin have some long awaited test results: After 69 years, they have captured on video a drop of pitch, also known as bitumen or asphalt.
With a camera trained on a glass funnel containing a generous dollop of the substance, so thick that it appears as a solid at room temperature, it finally happened.
You can see the dramatic moment in this video above, which proves conclusively that pitch is indeed a liquid, according to Nature.
Pitch is estimated to be about 2 million times more viscous than honey and 20 billion times more so than water, Nature says.
The magazine writes that the experiment, started in 1944, has been going on so long that the name of the scientist who began it has been forgotten. For years, the glass funnel and stand collected dust on a laboratory shelf at Trinity, where it no doubt yielded several drops over the decades that no one was around to witness:
"Physicists at Trinity College recently began to monitor the experiment again. Last April they set up a webcam so that anyone could watch and try to be the first person ever to witness the drop fall live.
At around 5 o'clock in the afternoon on 11 July, physicist Shane Bergin and colleagues captured footage of one of the most eagerly anticipated and exhilarating drips in science. "We were all so excited," Bergin says. "It's been such a great talking point, with colleagues eager to investigate the mechanics of the break, and the viscosity of the pitch."
Since 1961, John Mainstone has been the custodian of a similar, even older, pitch-drop experiment (yes, there's more than one) at the University of Queensland in Brisbane, Australia. That experiment is listed by Guinness as the longest-running laboratory experiment. While he has yet to personally witness a drop — which takes anywhere from 7 to 13 years to form — he has examined the Dublin video "over and over again".
"There were a number of things about it that were really quite tantalizing for a very long time pitch-drop observer like myself," he says.
Asked about the scientific import of the experiment, Trinity physicist Denis Weaire, says: "Curiosity is at the heart of good science, and the pitch drop fuels that curiosity."