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- Published: 18 July 2013
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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Long-term research: Slow science 2013-Mar-20
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Ig Nobels hail world's longest-running experiment 2005-Oct-12
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The Pitch Drop Experiment (University of Queensland)
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Johnston, R. World's slowest-moving drop caught on camera at last. Nature (2013). https://doi.org/10.1038/nature.2013.13418
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Published : 18 July 2013
DOI : https://doi.org/10.1038/nature.2013.13418
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Longest-running laboratory experiment
The Pitch Drop Experiment has been running since 1927 at the University of Queensland, Australia. It consists of black pitch contained in a glass funnel, with the entire apparatus enclosed in a container. It demonstrates that pitch is actually an extremely viscous liquid. Once the stem of the funnel was cut, the pitch slowly began to drip. In late 2000, the 8th drop fell. From this experiment it has been possible to demonstrate that the viscosity of pitch is about 100 billion times that of water. There is enough pitch still in the funnel for this famous experiment to run for another hundred years.
The experiment was initiated by the University of Queensland's first physics professor, Thomas Parnell.
After 69 years, 'pitch drop' experiment finally caught on video
By Dieter Bohn
Source Nature , Trinity College Dublin , and kottke.org
Share this story
:format(webp)/cdn.vox-cdn.com/uploads/chorus_asset/file/14396679/pitch-drop-640.1419979734.jpg "longest running experiment live")
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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July 22, 2013
Scientists capture pitch drop on camera for first time (w/ Video)
by Trinity College Dublin
The Pitch Drop experiment set up in 1944 at Trinity College Dublin's School of Physics is one of the world's oldest continuously running experiments.
The experiment was established to demonstrate that pitch is a material that flows, albeit with an incredibly high viscosity hence extremely slowly. Also known as asphalt or bitumen, pitch appears to be solid at room temperature.
Whilst pitch has been dropping from the funnel in Trinity since 1944, nobody had ever witnessed a drop fall. It happens roughly only once in a decade.
In May of this year, with the latest drop about to fall, Professor Shane Bergin broadcast the experiment via the web. On July 11th, the drop dripped. You can see a time lapse video of this here.
Tracking the evolution of the drop, Professor Denis Weaire and Professor Stefan Hutzler, and David Whyte calculated the viscosity of the pitch to be 2x107 Pa s, approximately 2 million times the viscosity of honey.
Commenting on the significance of the demonstration, Professor Shane Bergin stated: "People love this experiment because it gets to the heart of what good science is all about – curiosity. Over these past few months, there has been constant chat about when the drip would drop. I watched the time lapse video of the pitch drop falling over and over again. I was amazed. This was the first time this phenomenon was ever witnessed!"
The School of Physics at Trinity College Dublin has many old demonstrations and ancient experimental kit. The Pitch Drop experiment was begun when Nobel Prize winner Earnest Walton was head of the department.
The University of Queensland have a similar experiment that was begun in 1927. The Guinness Book of World Records ranks this as the world's longest running experiment. Whilst 8 drops have fallen in this experiment, nobody has ever witnessed one fall.
Whilst it will be roughly another 10 years before the next drop falls, you can look at the live experiment here.
Provided by Trinity College Dublin
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IMAGES
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COMMENTS
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.
Watch University of Queensland's The Pitch Drop Experiment on Livestream.com.
The Pitch Drop experiment holds the Guinness World Record for the longest-running laboratory experiment.
A 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 , also known as asphalt.
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.
The actual experiment began in October 1930 and is now recognised by Guinness World Records as the longest-running laboratory experiment – and in all that time no one has ever witnessed a...
Longest-running laboratory experiment. The Pitch Drop Experiment has been running since 1927 at the University of Queensland, Australia. It consists of black pitch contained in a glass funnel, with the entire apparatus enclosed in a container.
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:...
The Guinness Book of World Records ranks this as the world's longest running experiment. Whilst 8 drops have fallen in this experiment, nobody has ever witnessed one fall.
The world's longest-running experiment, designed to measure the flow of pitch, has been running since 1930. This latest pitch drop is the 9th and took around...