The Guinness world record for the longest-running experiment is held by scientists at the University of Queensland, Australia who have been running the 'Pitch Drop Experiment' for nearly 100 years, which could go on for another century. Started in 1927 by an Australian physicist named Thomas Parnell, the experiment aims to measure both the fluidity and high viscosity of a substance called pitch, which is a derivative of tar and is regarded as the world's thickest known fluid that was used for waterproofing boats in the past.
What is the experiment?
Parnell heated a sample of pitch and poured it into a glass funnel with a sealed stem. He allowed the pitch to cool and settle for three years. In 1930, he cut the funnel's steam and waited. According to the university, "the experiment was set up as a demonstration" and has not been kept under special environmental conditions. Instead, it is kept in a display cabinet so the rate of flow of the pitch varies with seasonal changes in temperature.
After Parnell, the late Professor John Mainstone became the experiment's custodian in 1961 and kept it ticking for 52 years. Since the experiment's inception, the pitch has slowly dripped out of the funnel - so slowly that it took eight years for the first drop to fall, and more than 40 years for another five to follow.
As of the last update, nine drops had fallen with another one expected to drop this decade. However, owing to various glitches, no one has actually seen a drop fall.
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Experiment's finding
While pitch feels solid -- even brittle at room temperature, which can be easily shattered with a hammer, the experiment demonstrated that the viscosity of the substance is about 100 billion times that of water. Additionally, there is enough pitch still in the funnel for the famous experiment to run for another hundred years.
In 2005, Maidstone and Parnell (posthumously) were awarded the Ig Nobel prize - a satirical award that highlights obscure and trivial achievements in scientific research. The Ig Nobel prize aims to honour work that makes people laugh but also makes them think.
