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Drip Drops


You may recall a story from 2013 of the TCD Physics Pitch Drip experiment. It had been running since 1944, and its aim was to demonstrate that some apparently solid materials can actually be liquids of extraordinarily high viscosity.


In the experiment, a funnel was filled with Pitch (a variant of tar consisting mainly of bitumen, apparently) and it was left to...well... drip. Into a container waiting patiently underneath. Waiting for several years. A drip would fall about every decade. A similar experiment has been running in Queensland since 1930, and its drip rate is graphed above.


The apparatus was left in a glass display cupboard and largely forgotten for decades, until it was moved in 2013 and a time-lapse system was set up to catch its next drip. The video is available at the link below and was met with something approaching excitement at the time.

It allowed TCD Physics Dept to calculate the viscosity of pitch to be about 20,000,000 Pa s - 2 million times that of honey.


But now today we have dramatic news. The drip has dropped again. Only five years since the last event, and five years ahead of schedule! A quick calculation would suggest that the viscosity has halved, but of course, with only something like 8 data points - and several of them of dubious worth, because for decades nobody was paying any attention - that conclusion might be a little premature.


But I bet that physicists in Trinity spend far more time discussing and/or analysing this today than they do any of the several multi-million euro research projects they have going on.


https://www.tcd.ie/Physics/news-events/news/pitchtardrop/

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