World's longest lab experiment still going 85 years later

In 1927, Professor Thomas Parnell of the University of Queensland set out to teach his students a lesson, and that lesson is still going on today and has at least another 100 years to go.

The physics professor wanted to demonstrate to his pupils that solid material could have viscous properties, so he used tar pitch, a derivative of coal once used to waterproof boats, in an experiment to prove his point.

At room temperature, pitch appears to be solid and can even shatter if hit with a hammer, but despite its look and feel, pitch can also flow at room temperature — just really, really slowly.

To conduct the Pitch Drop Experiment, Parnell melted some pitch into a glass funnel with a sealed stem and allowed it to settle for three years. In 1930, the funnel was unsealed, clearing the way for the pitch to flow freely, but it sure did take its sweet time.

Eight years went by before the first drop of pitch hit the beaker below, and it was another nine years before the second drop hit. Parnell passed away in September 1948, but a third drop was recorded in 1954, before the Pitch Drop Experiment was stored away in a cupboard.

The experiment may never have seen the light of day again had it not been for John Mainstone.

Mainstone, who joined the University of Queensland physics department in 1961, took over the project after a colleague discovered the "weird" object in the cupboard. With some coaxing, Mainstone also got the university in 1975 to publicly display the experiment in a cabinet in the foyer of the department building.

Now, the Pitch Drop Experiment has its own live webcam. The eighth and most recent drop was recorded on 28 November 2000, but wouldn't you know it? The camera malfunctioned when it fell. To date, no one has actually witnessed a drop fall.

The experiment isn't kept under special environmental conditions, so the rate of flow fluctuates with seasonal temperatures. However, Mainstone expects that the ninth drop will occur sometime in 2013 and adds that it could be at least another 100 years before all the pitch flows out of the funnel.

It's pretty safe to say Parnell got his point across, albeit slowly, and his perseverance didn't go unrecognised. In 2005, Parnell and Mainstone were awarded the Ig Nobel Prize, an America parody of the Nobel Prize, for physics. The Pitch Drop Experiment also holds the world record for being the longest running lab experiment in the Guinness Book of Records.