What’s slower than ketchup, but faster than glass?
OK — trick question because glass actually is a solid.*
An old experiment, dusty and shelved for much of its duration, finally let fall a drop of pitch, also known as bitumen or asphalt, in front of cameras for the first time. Set up in 1944 at Trinity College Dublin — by no one anyone can remember, with an untold number of drops in its lifetime fallen unseen — the drip that looks like a solid but is actually moving very, very slowly, dropped on July 11 at around 5 p.m., with web-cameras faithfully recording the action.
And action it was.
“It takes 7 to 13 years for a drop to form, but only a tenth of a second for it to fall,” reported Nature News. A similar experiment set up in 1927 at the University of Queensland in Brisbane, Australia, has had eight drops fall, but the custodian of that experiment since 1961, John Mainstone, hasn’t seen any of them fall with his own eyes and just missed recording the last one that fell in 2000 because the camera was offline.
In Dublin, physicist Shane Bergin and colleagues had dusted off the experiment and set up the web cameras last April to capture the pitch drop. “We were all so excited,” Bergin told Nature News. “It’s been such a great talking point, with colleagues eager to investigate the mechanics of the break, and the viscosity of the pitch.”
Based on the timing of the flow, the team identified the pitch as being around 2 million times more viscous than honey.
For his part, Mansfield is, as one might expect, drooling over the data. “I have been examining the video over and over again,” he told Nature News, ”and there were a number of things about it that were really quite tantalizing for a very long time pitch-drop observer like myself.”