In 1927, an Australian physics professor poured some black goo into a glass funnel to demonstrate that a substance that looked solid could nevertheless flow like a fluid. Nearly a century later, the experiment is still running, and in all that time only nine drops have fallen.

That is not a typo. Not nine drops per minute. Not nine drops per year. A grand total of nine drops since Calvin Coolidge was president of the United States, Charles Lindbergh flew across the Atlantic, and people still regarded radio as fairly cutting-edge technology. The experiment has survived the Great Depression, a world war, the invention of television, the atomic bomb, the space program, the Internet, several generations of university students, and presumably more than one administrator who looked at the thing and asked, “Do we really still need this?”

We do, because this is the Pitch Drop Experiment at the University of Queensland, and it may be the finest demonstration ever devised of the scientific principle known as “this could take a while.”

The Substance That Refuses to Pick a Side

The star of the experiment is pitch, a black, tar-like material once commonly used for things such as waterproofing boats. At room temperature, pitch does a very convincing impersonation of a solid. Touch it, and it feels hard. Hit it with a hammer, and it can shatter. All of which would seem to settle the question rather neatly.

Except pitch flows. It just does so with the urgency of someone who has been told there is a mandatory meeting at 4:30 on Friday afternoon.

This is not the first time we have wandered into the surprisingly slippery question of whether something is really a solid or a liquid. We previously looked at the persistent myth that old window glass is slowly flowing downward because glass is actually a liquid, and we have also tackled the considerably more important scientific question of whether a cat should be classified as a liquid or a solid. Pitch, however, has the advantage of actually cooperating with the experiment. Given enough time, it really does flow—although “enough time” turns out to mean that everyone involved should probably have a succession plan.

Pitch is an extraordinarily viscous fluid. “Viscosity” is essentially a measure of how resistant a fluid is to flowing. Water has low viscosity. Honey has considerably more. Pitch looks at honey and thinks it should really learn some patience.

In a 1984 scientific analysis of the experiment, researchers calculated the viscosity of the Queensland pitch at approximately 2.3 × 10⁸ pascal-seconds—roughly 230 billion times the viscosity of water. The University of Queensland often rounds that comparison more generally to about 100 billion times more viscous. Either way, pitch is definitely flowing; you just need a more generous definition of “hurry up.”

Professor Parnell Pours Some Pitch and Dooms Future Generations to Waiting

The experiment was created by Thomas Parnell, the University of Queensland’s first professor of physics. Parnell was not exactly a stranger to excitement. Born in England in 1881, he studied at Cambridge, where he boxed, wrestled, rowed, ran cross-country, and conducted physics research at the famous Cavendish Laboratory.

Then World War I came along. Parnell joined the Australian Imperial Force and served on the Western Front, eventually becoming a gas officer whose duties included the somewhat alarming responsibility of defusing unexploded gas shells. After the war, he returned to the University of Queensland, refunded £437 in excess salary the university had paid him during his military service, and asked that the money be used to help returning servicemen attend college.

So, to recap, Thomas Parnell boxed, served on the Western Front, dismantled unexploded chemical weapons, gave money back to his employer, and eventually became famous for watching tar move. Careers take unexpected turns.

In 1927, Parnell heated a quantity of pitch until it was sufficiently fluid to pour into a glass funnel. The bottom of the funnel’s stem was sealed, and then he waited for three years before the experiment even officially got going. In October 1930, the pitch had cooled and settled, so the sealed end of the funnel was cut open and gravity was finally free to do its work.

Gravity apparently discovered that it had cleared its calendar for the afternoon unnecessarily.

Eight Years Later…

The first drop fell in December 1938. By then, Franklin Roosevelt was in the White House, Hitler had annexed Austria, Orson Welles had broadcast The War of the Worlds, and Mickey Mouse had been joined by Donald Duck. The pitch had traveled a few centimeters.

The second drop fell in February 1947. The third arrived in April 1954, the fourth in May 1962, and the fifth in August 1970. By that point, a pattern had emerged: every seven to nine years, give or take, the pitch would finally surrender another drop.

Event	Date
Funnel stem opened	October 1930
First drop	December 1938
Second drop	February 1947
Third drop	April 1954
Fourth drop	May 1962
Fifth drop	August 1970
Sixth drop	April 1979
Seventh drop	July 1988
Eighth drop	November 2000
Ninth drop	April 2014

Parnell himself did not get to enjoy much of this astonishingly slow-motion success. He died in 1948, having lived long enough to see—or, more accurately, to learn about—the first two drops. Actually seeing one fall would prove remarkably difficult.

Enter the Unluckiest Man in Experimental Physics

In 1961, physicist John Mainstone became custodian of the Pitch Drop Experiment, and he would remain responsible for it for the next 52 years. Five drops fell during that period. John Mainstone saw none of them.

This was not because he was neglecting his responsibilities. Quite the opposite. Mainstone became fascinated with the experiment and spent decades trying to witness the brief moment when the elongated neck of pitch finally broke and a drop separated. The problem was that this particular lump of pitch seemed to possess both patience and a malicious sense of timing.

The 1979 Drop: Defeated by Sunday

By April 1979, the sixth drop looked ready to go. Mainstone checked it on Saturday evening and found it still hanging there. He went home and did not return on Sunday. When he arrived at the university early Monday morning, the drop was sitting in the beaker.

After waiting nine years for the event, Mainstone had missed it by a weekend. Still, another opportunity would come along. He only had to wait until 1988.

The 1988 Drop: Defeated by Tea

The seventh drop was particularly promising because the Pitch Drop Experiment was being displayed at Brisbane’s World Expo 88. Mainstone was there. The drop was ready. This time he was going to see it.

And then he made the sort of decision that probably haunted him every time someone subsequently offered him a hot beverage. He went to get a cup of tea.

As Mainstone later recounted in an interview with Radiolab, he walked away briefly, returned, and discovered that the pitch had dropped. He estimated that he may have missed the event by as little as 15 minutes.

Somewhere in Brisbane that day, John Mainstone discovered that a watched pot may never boil, but an unwatched lump of pitch will absolutely drop the moment you go looking for tea.

Technology Will Save Us

By the time the eighth drop began approaching its moment of destiny in 2000, the world had changed. We had computers, digital cameras, and the Internet. Humanity no longer needed to rely upon a physicist physically standing beside a funnel for years at a time. A camera could watch the experiment continuously and record the historic event whenever it happened.

At last, science had defeated the pitch.

The eighth drop fell on November 28, 2000. The recording system failed at the critical moment. According to the University of Queensland, an unfortunately timed blackout prevented the event from being captured.

At this point, one begins to suspect the pitch knew exactly what it was doing.

At Least There Was an Ig Nobel Prize

By now, the experiment had attracted worldwide attention, which was understandable. Most scientific demonstrations do not require researchers to make arrangements for their eventual successors.

In 2005, Mainstone and the late Thomas Parnell received the Ig Nobel Prize in Physics for their patience in conducting an experiment that had been underway since 1927 and produced approximately one drop every nine years. The Ig Nobel Prizes honor research that makes people laugh and then think, which seems almost suspiciously designed for the Pitch Drop Experiment.

Parnell received his award posthumously, having been dead for 57 years. Mainstone attended the ceremony, which may have been one of the few major events associated with the experiment that had the courtesy to occur while he was actually present.

Meanwhile, Air-Conditioning Was Interfering With Science

Something else had happened to the pitch: it was slowing down. The early drops generally arrived about every seven to nine years, while the eighth took more than 12 years and the ninth took more than 13.

One culprit was an invention most Queenslanders probably regarded as an improvement: air-conditioning. The experiment was never conducted under carefully controlled laboratory conditions. It sat in a display cabinet, exposed to ordinary changes in the temperature of the building, and that mattered because the viscosity of pitch changes dramatically with temperature.

In the mid-1990s, according to the University of Queensland Physics Museum, nearby lecture theaters were air-conditioned. The cooler environment slowed the pitch. Humanity had spent decades trying to make indoor life more comfortable, and the pitch responded by adding several years to its schedule.

Someone Finally Saw a Pitch Drop Fall

By 2013, Mainstone was still waiting. But that year, something extraordinary happened. Unfortunately for him, it happened in Ireland.

Trinity College Dublin had its own pitch-drop experiment, established in 1944. Like Queensland’s experiment, it demonstrated the unexpectedly fluid behavior of something that looked thoroughly solid. In May 2013, with a drop apparently nearing separation, researchers set up a webcam.

On July 11, it happened. The pitch fell, and the camera worked. For the first time, the fall of a pitch drop had been captured on video. Trinity College announced the achievement several days later.

Mainstone finally got to watch a pitch drop fall. It just wasn’t his pitch. He reportedly examined the Irish video repeatedly, studying an event he had spent more than half a century trying to see firsthand.

John Mainstone’s Final Wait

The ninth Queensland drop was now getting very close. This time there would be no chances taken. Three cameras watched the apparatus, and tens of thousands of people around the world registered to watch the livestream. Surely Mainstone would finally see his drop.

In August 2013, John Mainstone suffered a stroke and died at the age of 78. He had cared for the experiment for 52 years without ever witnessing a single drop fall. The University of Queensland announced his death while the ninth drop was still hanging from the funnel. It fell—or at least began the surprisingly complicated process of falling—about eight months later.

There is something unexpectedly poignant about that. Mainstone spent most of his professional life caring for an experiment operating on a timescale that simply did not care about the length of a human life. He understood that he might never see what he was waiting for, yet he kept the experiment going so somebody eventually would.

Science occasionally requires brilliance. Sometimes it requires patience. And sometimes it requires 52 years of patience followed by the humility to leave the job to somebody else.

The Ninth Drop Somehow Made Falling Complicated

By 2014, Professor Andrew White had succeeded Mainstone as custodian. He had three cameras trained on the experiment, the world was watching, and the pitch apparently responded to this level of supervision by finding another way to make things difficult.

The eighth drop was still sitting in the receiving beaker below the funnel. As the ninth drop stretched downward, it eventually reached the old drop. Instead of snapping free and making the dramatic little plunge everyone had waited 13 years to see, Drop No. 9 simply touched Drop No. 8.

Analysis of time-lapse images later determined that this happened on April 12, 2014. Researchers could identify the touchdown because the ninth drop’s descent slowed from about 0.25 millimeters per day to roughly 0.1 millimeters per day. Just contemplate the level of excitement involved in discovering that something has suddenly slowed down to one-tenth of a millimeter per day. This is why physicists require specialized training.

But the ninth drop still had not broken away from the funnel.

So They Tried to Move the Beaker

On April 24, White decided to replace the beaker containing the accumulated drops so future drops would once again have room to fall freely. The plan sounded simple enough, which should already make you nervous.

White lifted the bell jar surrounding the apparatus. An old seal caused part of the setup to move unexpectedly, the wooden base wobbled, and the ninth drop snapped off.

After 13 years of waiting, one of the most closely monitored drops in scientific history was finally detached not by gravity alone, but during an attempt to move the furniture.

The University of Queensland therefore has a wonderfully awkward answer to the seemingly simple question, “When did the ninth drop fall?” It touched down on April 12, but it separated on April 24. The university reported the separation on April 24, while later scientific analysis identified April 12 as the touchdown date.

After waiting more than a decade for one drop, even defining when it had actually “dropped” required additional research.

And Now We Wait for Number Ten

The original beaker was removed after the ninth drop, giving the next generation of pitch plenty of room to perform. As of 2026, the University of Queensland reports that only nine drops have fallen, and Drop No. 10 is still forming.

Back in 2014, the university predicted that the next drop would arrive sometime in the 2020s, which is roughly the same timeframe we were given for when to expect the dishwasher repairman to show up. As of 2026, the pitch is keeping its options open.

The experiment is still streamed online, meaning that anyone with an Internet connection can now participate in one of science’s most unusual spectator sports. You can watch the live feed of the University of Queensland Pitch Drop Experiment yourself. The pace is not particularly exciting, but it is still more enjoyable than half of the options available on Netflix.

But Wait: Queensland Isn’t Even the Oldest Pitch Experiment

At this point, the story seems straightforward enough. The Queensland Pitch Drop Experiment began in 1927 and holds the Guinness World Record for the longest-running laboratory experiment.

Except there are older pitch demonstrations, because apparently one civilization-spanning experiment involving slowly moving tar was not enough.

Wales Has Been Waiting Since 1914

At Aberystwyth University in Wales, G. T. R. “Taffy” Evans set up a pitch-drop experiment on April 23, 1914. That was 13 years before Parnell began the Queensland experiment.

Its scientific output has been remarkable: not one drop has fallen.

More than a century later, the pitch is still making its way through the funnel. Queensland, with its nine drops, is starting to look positively reckless.

This creates an apparently awkward problem for Queensland’s claim to fame. Guinness World Records recognizes the Australian experiment as the world’s longest-running laboratory experiment, while Aberystwyth describes its own 1914 apparatus as “possibly the world’s longest-running experiment.” The claims are phrased differently, and the institutions do not use exactly the same criteria. What is beyond dispute is that the Welsh pitch-drop setup predates Parnell’s by 13 years—even though, unlike its comparatively hyperactive Australian cousin, it has yet to produce a single drop.

Science, it turns out, occasionally requires footnotes even when nothing has happened.

Scotland Says, “That’s Cute”

And then there is Scotland. The National Museum of Scotland has a pitch-drop demonstration constructed in Edinburgh in 1902, making it 12 years older than Aberystwyth and 25 years older than Queensland.

The museum describes it cautiously as possibly the oldest pitch-drop demonstration in the world. Unlike Queensland, however, it does not have a complete century-long observational record, so the precise history of its dripping is uncertain.

The Scottish apparatus has produced at least a couple of drops. One fell between June 4 and June 6, 2016, shortly after the museum had moved the equipment, although officials believe the move helped trigger the drop. Even after waiting more than a century, somebody managed to jostle it. This seems to be an occupational hazard of pitch-drop science.

So What Has This Actually Taught Us?

It is tempting to treat the Pitch Drop Experiment as a novelty—a century-long joke involving a funnel and a substance with poor time-management skills. But the underlying lesson is genuinely interesting.

Our everyday categories of “solid” and “liquid” are useful, but the behavior of real materials can be far more complicated. A substance may seem absolutely solid on the timescale of a human hand pressing against it and yet unmistakably flow if you are willing to watch it for several decades.

The experiment also shows how dramatically temperature affects viscosity, illustrates the difficulty of conducting a very long experiment under uncontrolled environmental conditions, and has allowed researchers to estimate the physical properties of pitch. Perhaps most importantly, it demonstrates that some scientific questions cannot be bullied into producing answers on a convenient schedule.

Sometimes nature takes its time. Sometimes a very long time.

The Experiment That Outlived Its Experimenter

Thomas Parnell probably never imagined that anyone would still be discussing his classroom demonstration nearly a century later. He poured the pitch in 1927, opened the funnel in 1930, and died in 1948. John Mainstone inherited responsibility for it in 1961 and spent the next 52 years watching over it before his death in 2013.

The pitch remains.

Somewhere in a glass funnel at the University of Queensland, Drop No. 10 is continuing its almost imperceptible journey downward. Students walk past it. Scientists check it. Cameras record it. People around the world can watch it live.

Eventually, presumably, it will fall. Maybe tomorrow. Maybe next year. Maybe the pitch has read the university’s prediction that it will happen during the 2020s and is now determined to make everyone look foolish.

After nearly a century, one thing seems certain: it will happen when nobody is expecting it.

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