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.
Contents
The pitch drop experiment at the University of Queensland
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.[1] The ninth drop is expected to fall in 2012 or 2013. [2]
This is recorded in the Guinness Book of 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 pre-dated by two other still-active scientific devices, the Oxford Electric Bell (1840) and the Beverly Clock (1864).
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 resided. The temperature stability has lengthened each drop's stretch before it separates from the rest of the pitch in the funnel.
In October 2005, John Mainstone and the late Thomas Parnell were awarded the Ig Nobel Prize in Physics, a parody of the Nobel Prize, for the pitch drop experiment.[3]
To date, no one has ever witnessed a drop fall. The experiment is in the view of a webcam but technical problems prevented the most recent drop from being recorded.[4][5] 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.
Timeline
| Date | Event | Duration
(months) |
Duration
(years) |
|---|---|---|---|
| 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 |
See also
References
- ↑ Edgeworth, R., Dalton, B.J. & Parnell, T.. "The Pitch Drop Experiment". http://www.physics.uq.edu.au/physics_museum/pitchdrop.shtml. Retrieved 2007-10-15.
- ↑ "Is this the most boring experiment ever? Scientists watch drops of pitch form - and there have been eight in 75 years". http://www.dailymail.co.uk/sciencetech/article-2142928/Is-boring-experiment-Scientists-watch-drops-pitch-form--75-years.html. Retrieved 2012-05-13.
- ↑ The 2005 Ig Nobel Prize Winners
- ↑ University of Queensland page on the Pitch Drop experiment
- ↑ Link to Webcam
External links
es:Experimento de la gota de brea fr:Expérience de la goutte de poix it:Esperimento della goccia di pece he:ניסוי טיפת הזפת nl:Pekdruppelexperiment ru:Опыт с капающим пеком fi:Pikitippakoe zh:瀝青滴漏實驗
