Century-old Pitch Drop experiment still drips—will anyone finally see it fall?

One of the world’s strangest scientific experiments is still running after nearly a century. Started in 1927, the Pitch Drop experiment at the University of Queensland tracks the slow flow of a thick, tar-like substance. Despite its long history, no one has ever witnessed a drop actually fall—until now, a live-stream monitors the experiment, though past attempts to twitch it have failed.

Professor Thomas Parnell set up the experiment to show that pitch—a thick, tar-derived material—appears solid but is in fact a very slow-moving fluid. The first drop took 98 months to form and fall, followed by the second after 99 months. Later drops slowed further: the seventh took 111 months, the eighth 148 months, and the ninth 161 months.

The experiment gained fame as the 'world’s longest continuously running lab experiment,' earning a Guinness World Record. Yet for decades, no one managed to see a drop fall in real time. John Mainstone, the experiment’s previous custodian, missed the seventh drop in 1988. Even with a live-stream introduced in later years, technical issues caused the 2000 and 2014 drops to go unrecorded. The experiment will mark its 100th anniversary in 2027, with the next drop expected sometime in the 2020s. Researchers believe the experiment could continue for another century, as the pitch inside the funnel remains thick enough to drip at an agonisingly slow pace.

The Pitch Drop experiment remains a unique demonstration of patience in science. Though no one has yet seen a drop land, the live-stream keeps watch for the next event. With at least another 100 years to go, the experiment will likely outlast many more generations of researchers.