So the other day something amazing happened, the pitch dropped and was caught on video! What does this mean? Well at first I had no idea, except that a lot of people on the internet were making a big deal about it so I thought I’d check it out and find out what all the fuss was about.
Firstly, what is pitch? I’m not talking about music pitch, where to drop it would be lowering the way you sing. What I’m talking about is the sticky tar looking stuff used for bitumen or asphalt. It can be made from petroleum products or plants and is a hugely viscous substance, think of an extremely thick honey.
Image from markhillary
So that’s what pitch is, not very exciting in my books, so what’s everyone talking about? Well it turns out in 1927 there was an experiment set up, here in Australia, by Professor Thomas Parnell at the University of Queensland to show students about the fluidity and viscosity (how thick the liquid is) of pitch. That even though it looked like a solid at room temperature it was actually an extremely viscous liquid (many many times that of water).
Parnell warmed the pitch up, poured it into a glass funnel that was sealed off at the bottom and then waited three years for the pitch to completely settle out evenly before cutting the sealed stem of the funnel. The experiment takes into account the physics of how liquids flow as well as the effect of temperature on the pitch itself to calculate the viscosity of the pitch. With gravity, the extremely viscous material slowly drips out of the funnel and the dates of when a drop falls is recorded, as this is on the scale of decades (the last drop being back in November 2000).
There is a live feed for the UQ experiment to catch that next drop getting ready to fall yet still, unless you’re a physics lecturer or enthusiast this isn’t very invigorating stuff. Where it does get unique though is that no one has ever captured the drop of pitch on camera, until now! (unfortunately due to technical issues they could not film the last one)
A similar experiment was set up in 1944 at Trinity College in Dublin and on July 11th they captured one of their drops on video.
This pitch-drop experiment is the world’s longest continuously running experiment and has won Parnell and Professor John Mainstone, the long time custodian of the experiment, an Ig Nobel prize. Ig nobel prizes are a slight parody on the nobel prizes but best described by creator Marc Abrahams as “honouring achievements that make people laugh, then make them think.”
Fun fact – the term ‘pitch black’ actually comes from this type of pitch, due to its extremely dark color.
One downside to the UQ experiment however is that as the experimental conditions were not controlled at the start (the set-up is now in a display cabinet), the viscosity calculations are only estimates as the flow can change with the temperature seasonally. But still it must be admitted, you’d need a lot of patience for an experiment this long!
Science, Stuff and Things 