australian tar experiment

Pitch Drop experiment

PhD students inspect the Pitch Drop experiment.

We're home to the famous Pitch Drop experiment, which holds the Guinness World Record for the longest-running laboratory experiment .

The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar that is the world's thickest known fluid and was once used for waterproofing boats.

Thomas Parnell, UQ's first Professor of Physics, created the experiment in 1927 to illustrate that everyday materials can exhibit quite surprising properties.

At room temperature pitch feels solid - even brittle - and can easily be shattered with a hammer. But, in fact, at room temperature the substance - which is 100 billion times more viscous than water - is actually fluid.

The experiment explained

In 1927 Professor 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, and then in 1930 he cut the funnel's stem.

Since then, 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.

Now, 87 years after the funnel was cut, only nine drops have fallen - the last drop fell in April 2014 and we expect the next one to fall sometime in the 2020s.

The experiment was set up as a demonstration and is not kept under special environmental conditions - it's kept in a display cabinet - so the rate of flow of the pitch varies with seasonal changes in temperature.

The late Professor John Mainstone became the experiment's second custodian in 1961. He looked after the experiment for 52 years but, like his predecessor Professor Parnell, he passed away before seeing a drop fall.

In the 86 years that the pitch has been dripping, various glitches have prevented anyone from seeing a drop fall.

See for yourself

To see the experiment for yourself, view the physical set-up in its display case in the foyer of the Parnell Building (Building 7).

Alternatively, you can watch the experiment's live video stream . More than 35,000 people from some 160 countries are registered to view the stream.

Professor Andrew White is the Pitch Drop's third and current custodian.

Email your Pitch Drop enquiry to [email protected] .

World's slowest-moving drop caught on camera at last

Richard Johnston

Nature ( 2013 ) Cite this article

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Once-forgotten 'tar pitch' experiment yields results after seven decades.

How long would you be willing to wait for a drop of the black stuff in Dublin? After 69 years, one of the longest-running laboratory investigations in the world has finally captured the fall of a drop of tar pitch on camera for the first time. A similar, better-known and older experiment in Australia missed filming its latest drop in 2000 because the camera was offline at the time.

The Dublin pitch-drop experiment was set up in 1944 at Trinity College Dublin to demonstrate the high viscosity or low fluidity of pitch — also known as bitumen or asphalt — a material that appears to be solid at room temperature, but is in fact flowing, albeit extremely slowly.

It is a younger and less well-known sibling of an experiment that has been running since 1927 at the University of Queensland in Brisbane, which Guinness World Records lists as the world’s longest-running laboratory experiment (see: Long-term research: Slow science ). Physicist Thomas Parnell set it up because he wanted to illustrate that everyday materials can exhibit surprising properties. In the past 86 years that experiment has yielded eight drops, with the ninth drop now almost fully formed and about to fall.

John Mainstone has been custodian of the Queensland experiment since 1961, and has yet to see or capture the fall of a drop — unsurprising given that it takes 7 to 13 years for a drop to form, but only a tenth of a second for it to fall.

Pitch-drop experiments involve heating a sample of pitch and pouring it into a sealed glass funnel. The pitch is given time — three years in Parnell’s experiment — to settle and consolidate before the sealed stem of the funnel is cut.

The origins of the Dublin experiment are now lost to history. It may have been part of a push by the physicist and Nobel prizewinner Ernest Walton, a professor at Trinity College Dublin, to promote science demonstrations for educational purposes. Over the years, the identity of the scientist who began the experiment was forgotten, and the experiment lay unattended on a shelf where it continued to shed drops uninterrupted while gathering layers of dust.

Watching it fall

Physicists at Trinity College recently began to monitor the experiment again. Last April they set up a webcam so that anyone could watch and try to be the first person ever to witness the drop fall live.

At around 5 o'clock in the afternoon on 11 July, physicist Shane Bergin and colleagues captured footage of one of the most eagerly anticipated and exhilarating drips in science. “We were all so excited,” Bergin says. “It’s been such a great talking point, with colleagues eager to investigate the mechanics of the break, and the viscosity of the pitch”.

The Trinity College team has estimated the viscosity of the pitch by monitoring the evolution of this one drop, and puts it in the region of 2 million times more viscous than honey, or 20 billion times the viscosity of water. The speed of formation of the drop can depend on the exact composition of the pitch, and environmental conditions such as temperature and vibration.

Asked about the value of this demonstration, Bergin’s colleague Denis Weaire says, “Curiosity is at the heart of good science, and the pitch drop fuels that curiosity”.

Scientists used to believe glass to be a slow-moving liquid as well — in part because old church window panes are thicker at the bottom — but it is now considered a solid 1 .

And the next one

Mainstone, who has spent most of his life waiting to see a drop fall with his own eyes, congratulated the Trinity College team. “I have been examining the video over and over again,” he says, ”and there were a number of things about it that were really quite tantalizing for a very long time pitch-drop observer like myself.”

The University of Queensland pitch-drop experiment can be viewed live via a webcam and has a broad following across the globe. The next Queensland drop is predicted to fall some time in 2013.

Zhao, J., Simon, S. L. & McKenna, G. B. Nature Communications http://dx.doi.org/10.1038/ncomms2809 (2013).

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July 19, 2013

World's Slowest-Moving Drop Caught on Camera At Last

The once-forgotten "tar pitch" experiment has yielded results after a seven-decade wait

By Richard Johnston & Nature magazine

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Long wait John Mainstone has been custodian of the Queensland experiment since 1961, and has yet to see or capture the fall of a drop — unsurprising given that it takes 7 to 13 years for a drop to form, but only a tenth of a second for it to fall.

Watching it fall Physicists at Trinity College recently began to monitor the experiment again. Last April they set up a webcam so that anyone could watch and try to be the first person ever to witness the drop fall live.

Asked about the value of this demonstration, Bergin’s colleague Denis Weaire says, “Curiosity is at the heart of good science, and the pitch drop fuels that curiosity”.

Scientists used to believe glass to be a slow-moving liquid as well — in part because old church window panes are thicker at the bottom — but it is now considered a solid .

And the next one Mainstone, who has spent most of his life waiting to see a drop fall with his own eyes, congratulated the Trinity College team. “I have been examining the video over and over again,” he says, ”and there were a number of things about it that were really quite tantalizing for a very long time pitch-drop observer like myself.”

The University of Queensland pitch-drop experiment can be viewed live via a webcam and has a broad following across the globe. The next Queensland drop is predicted to fall some time in 2013.

This article is reproduced with permission from the magazine Nature . The article was first published on July 18, 2013.

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1927 - Famous Pitch Drop Experiment (1927)

Pitch Drop Experiment

The Pitch Drop experiment is designed to demonstrate that pitch is a high viscosity fluid and not a solid. It began in 1927, when Professor Thomas Parnell heated a sample of pitch and poured it into a glass funnel with a sealed stem. When the pitch was heated the viscosity was much lower and so it was clear that the pitch was a liquid. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. The now cooled pitch appeared to be a solid, it was hard to the touch and would shatter if hit by a hammer. However, from that date on the pitch has slowly dripped out of the funnel - so slowly that now, nearly 90 years later, the ninth drop has only just fallen. This shows that pitch is in fact a very slow moving fluid. The ninth drop touched the eighth drop (and so was considered to have fallen), on the 24th of April 2014.

The experiment was set up as a demonstration and is not kept under special environmental conditions, so the rate of flow of the pitch varies with seasonal changes in temperature. In the mid 1990s the University also began to air condition the nearby lecture theatres, cooling and thus slowing the eighth drop. Nonetheless, it is possible to make an estimate of the viscosity of this sample of pitch. It turns out to be about 100 billion times more viscous than water! The original beaker became too full for the drops to fall freely and so was removed after the ninth drop. It is now sitting to the left of the experiment and a fresh beaker has been placed underneath the tenth drop.

The Pitch Drop Experiment is famous, mentioned by several Brisbane authors and listed by the Guinness Book of Records in 2002 as the "world's longest-running laboratory experiment". Thomas Parnell and the late Prof John Mainstone were awarded the 2005 Ig Nobel Prize in Physics for starting and maintaining the experiment. It is continuously streamed live on the internet for fans wanting to follow its progress.

This item is part of the UQ Physics Museum ‘ 100 Years of Physics at UQ ’ Tour < Previous Item | Return to Tour Menu | Next Item >

This item is part of the UQ Physics Museum ‘ Parnell, Sumpner and Paul ’ Tour < Previous Item | Return to Tour Menu | Next Item >

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After 69 years, 'pitch drop' experiment finally caught on video

By Dieter Bohn

Source Nature , Trinity College Dublin , and kottke.org

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In 1927, a researcher at the University of Queensland in Australia began what's widely recognized as the longest-running experiment ever, the so-called "pitch drop." It's a simple set up: fill a flask with tar pitch and let it ooze out the bottom to see how quickly it flows, and eventually it makes a proper drop that falls down — about once every ten years or so. Tar pitch is a substance that appears to be solid, but in fact is actually a slowly flowing liquid. However, since the beginning of that experiment human eyes have never actually seen the pitch drop from the bottom of the flask — the last time the Queensland experiment dropped, the webcam that was set up to see it failed at precisely the wrong moment.

Fortunately, another experiment was also set up in 1944 at Trinity College in Dublin, Ireland . At 5PM local time on July 11th, the drop finally happened and was caught on video. You can see a time-lapse video of the event below, or tune in to the live view of the original experiment at the University of Queensland to wait for the next drop. Fair warning: it'll be awhile. If you're interested in learning more about the experiment, Radio Lab did a show on the subject this past February .

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Longest experiment sees pitch drop after 84-year wait

By Lisa Grossman and Celeste Biever

17 April 2014

Video: Pitch drops again in world’s longest experiment

The pitch has dropped – again. This time, the glimpse of a falling blob of tar, also called pitch, represents the first result for the world’s longest-running experiment.

Sadly however, the glimpse comes too late for a former custodian, who watched over the experiment for more than half a century and died a year ago.

Up-and-running since 1930, the experiment is based at the University of Queensland in Australia and seeks to capture blobs of pitch as they drip down, agonisingly slowly, from their parent bulk.

It was pipped to the post last year when a similar experiment, set up in 1944 at Trinity College Dublin in Ireland, captured the first ever video footage of a blob of pitch dropping .

In that instance, the blob separated from its parent bulk. By contrast, the Australian team filmed the collision between the ninth blob ever to fall and the eighth blob, which was sitting at the bottom of their beaker – but the ninth blob is still attached to the pitch above it.

Still, the Australian result is important because the experiment has a better set-up, says Stefan Hutzler , a member of the Trinity College Dublin team who used those results to calculate the pitch’s viscosity. “Theirs is in a glass container; they measure the temperature, measure the humidity as well,” he says. “Ours, we don’t really call it an experiment. It was really just sitting there on a shelf, going back to the 1940s.”

The fact that both experiments dropped within a year of each other is “just pure luck”, says Hutzler. Hot summer weather in Ireland last year may have influenced the timing.

The Queensland experiment already features in the Guinness World Records and won an IgNobel prize in 2005 . It was set up by physicist Thomas Parnell to illustrate that although pitch appears solid, shattering when hit with a hammer at room temperature, it is actually a very viscous liquid.

The eventual result follows several near misses, according to the University of Queensland. John Mainstone, who oversaw the experiment for more than 50 years until his death last August , missed observing the drops fall three times – by a day in 1977, by just five minutes in 1988 and, perhaps most annoying, in 2000, when the webcam that was recording it was hit by a 20-minute power outage.

“It’s a pity of course that the person in charge died about a year ago, so he never saw the drop,” Hutzler says. “He would have enjoyed that.”

The eighth and ninth drops each took about 13 years to fall, says current custodian Andrew White. By contrast, the seven drops that fell between 1930 and 1988 did so faster – at an average rate of one drop every eight years.

The next step is to see how long it takes the ninth drop to separate from the pitch above it: “It may tip over quickly or it might slow right down and take years to break away,” says White.

You can keep an eye on the ninth drop’s movements via a live web stream . The University of Queensland says it will work out who was watching when the pitch dropped and record their names for posterity.

The drop experiments show that the physics of a drop forming in a viscous material is still not well understood, Hutzler says – although he doesn’t think watching pitch for decades is necessarily the best way to study it. Using honey or some other less viscous fluid would give you better statistics.

“I think these experiments capture the imagination just because they go on for such a long time,” he says. The video of the drop in Dublin quickly went viral on YouTube. “Ironically, you have a very slow event happening, but the news spreads very quickly.”

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COMMENTS

Pitch Drop experiment - School of Mathematics and Physics ...
We're home to the famous Pitch Drop experiment, which holds the Guinness World Record for the longest-running laboratory experiment. The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar that is the world's thickest known fluid and was once used for waterproofing boats.
Pitch drop experiment - Wikipedia
At room temperature, tar pitch flows at a very low rate, taking several years to form a single drop. The University of Queensland pitch drop experiment, featuring its custodian, Professor John Mainstone (taken in 1990, two years after the seventh drop and 10 years before the eighth drop fell).
World's slowest-moving drop caught on camera at last | Nature
After 69 years, one of the longest-running laboratory investigations in the world has finally captured the fall of a drop of tar pitch on camera for the first time. A similar, better-known and...
World's Slowest-Moving Drop Caught on Camera At Last
After 69 years, one of the longest-running laboratory investigations in the world has finally captured the fall of a drop of tar pitch on camera for the first time. A similar, better-known and...
- The Famous Pitch Drop Experiment - University of Queensland
The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar once used for waterproofing boats. At room temperature pitch feels solid - even brittle - and can easily be shattered with a blow from a hammer.
Famous Pitch Drop Experiment - Physics Museum - The ...
The Pitch Drop experiment is designed to demonstrate that pitch is a high viscosity fluid and not a solid. It began in 1927, when Professor Thomas Parnell heated a sample of pitch and poured it into a glass funnel with a sealed stem.
After 69 years, 'pitch drop' experiment finally caught on video
In 1927, a researcher at the University of Queensland in Australia began what's widely recognized as the longest-running experiment ever, the so-called "pitch drop."
Longest experiment sees pitch drop after 84-year wait
Up-and-running since 1930, the experiment is based at the University of Queensland in Australia and seeks to capture blobs of pitch as they drip down, agonisingly slowly, from their parent bulk.
The Pitch Drop Experiment – Brisbane, Australia - Atlas Obscura
Begun in 1927 by Professor Thomas Parnell, this experiment was meant to reveal the surprising properties of an everyday material: pitch. Pitch is the name of a number of hard tar-like...
After 13 years, progress in pitch-drop experiment (w/ video)
After a wait of more than 13 years, the ninth drop of pitch collided ever so slowly with the eighth drop in the bottom of the beaker. The experiment was set up in 1927 to demonstrate that solid...