Pitch drop experiment
The pitch drop experiment is a long-term experiment which measures the flow of a piece of pitch over many years. Pitch is the name for any of a number of highly viscous liquids which appear solid, most commonly bitumen. At room temperature, tar pitch flows at a very slow rate, taking several years to form a single drop.
University of Queensland experiment
The most famous version of the experiment was started in 1927 by Professor Thomas Parnell of the University of Queensland in Brisbane, Australia, to demonstrate to students that some substances that appear to be solid are in fact very-high-viscosity fluids. Parnell poured a heated sample of pitch into a sealed funnel and allowed it to settle for three years. In 1930, the seal at the neck of the funnel was cut, allowing the pitch to start flowing. Large droplets form and fall over the period of about a decade. The eighth drop fell on 28 November 2000, allowing experimenters to calculate that the pitch has a viscosity approximately 230 billion (2.3×1011) times that of water. The ninth drop is expected to fall in 2013.
This is recorded in Guinness World Records as the world's longest continuously running laboratory experiment, and it is expected that there is enough pitch in the funnel to allow it to continue for at least another hundred years. This experiment is predated by two other still-active scientific devices, the Oxford Electric Bell (1840) and the Beverly Clock (1864), but each of these have experienced brief interruptions since 1937.
The experiment was not originally carried out under any special controlled atmospheric conditions, meaning that the viscosity could vary throughout the year with fluctuations in temperature. Some time after the seventh drop fell in 1988, air conditioning was added to the location where the experiment takes place. The temperature stability has lengthened each drop's stretch before it separates from the rest of the pitch in the funnel.
Professor Mainstone subsequently commented:
I am sure that Thomas Parnell would have been flattered to know that Mark Henderson considers him worthy to become a recipient of an Ig Nobel prize. Professor Parnell's award citation would of course have to applaud the new record he had thereby established for the longest lead-time between performance of a seminal scientific experiment and the conferral of such an award, be it a Nobel or an Ig Nobel prize.
To date, no one has ever witnessed a drop fall. The experiment is monitored by a webcam but technical problems prevented the most recent drop from being recorded. The pitch drop experiment is on public display on Level 2 of Parnell Building in the School of Mathematics and Physics at the St Lucia campus of the University of Queensland.
The current drop is expected to fall during the second half of 2013.
In May 2013 the experiment was moved to a temporary location. This caused some critics[who?] to question the integrity of the experiment with this movement coming at a time when the next drop is imminent.
|1927||Experiment set up|
|1930||The stem was cut|
|December 1938||1st drop fell||96–107||8.0–8.9|
|February 1947||2nd drop fell||99||8.3|
|April 1954||3rd drop fell||86||7.2|
|May 1962||4th drop fell||97||8.1|
|August 1970||5th drop fell||99||8.3|
|April 1979||6th drop fell||104||8.7|
|July 1988||7th drop fell||111||9.3|
|28 November 2000||8th drop fell||148||12.3|
- Long-term experiment
- William James Beal, Botanist who started a long-running seed germination experiment in 1879 that is due to end in 2100
- Edgeworth, R., Dalton, B.J. & Parnell, T. "The Pitch Drop Experiment". Retrieved 2007-10-15.
- Waugh, Rob. "Is this the most boring experiment ever? Scientists watch drops of pitch form - and there have been eight in 75 years". Daily Mail. Retrieved 2012-05-13.
- The 2005 Ig Nobel Prize Winners
- Mainstone, John. "A Comment from Professor Mainstone". University of Queensland. Retrieved 5 November 2012.
- University of Queensland page on the Pitch Drop experiment
- Link to Webcam