The iconic Pitch Drop experiment inches toward its tenth drop as cooling and physics quietly reshape its timeline
A Century-Long Experiment That Barely Moves
The Pitch Drop experiment, launched in 1927 by physicist Thomas Parnell at the University of Queensland, is nearing its 100-year milestone.
- Only nine drops have fallen in nearly a century.
- The tenth drop is forming, but separation remains distant.
It’s like watching a clock tick once a decade—time stretches, and patience becomes the experiment itself.
Solid or Liquid? The Physics Behind Pitch
Parnell designed the experiment to challenge perception: what appears solid may still flow.
- The material, asphalt (pitch), behaves as an extremely viscous liquid.
- It is 100 billion times more viscous than water and two million times thicker than honey.
Can something that shatters under a hammer also flow like a liquid? The pitch proves it can—just painfully slowly.
A Drop-by-Drop Timeline Across Decades
Since the funnel stem was cut, each drop has marked a rare scientific moment.
- First drop: December 1938
- Most recent (ninth): April 2014
- Gaps have stretched from 8–9 years to nearly 14 years
Despite continuous observation, no scientist has ever witnessed a drop fall live—a paradox for such a famous experiment.
Why the Experiment Is Slowing Down
The increasing delay between drops signals shifting internal dynamics.
- As pitch drains, pressure inside the funnel decreases, slowing flow.
- A subtle external factor also played a role: air conditioning installed in the 1980s.
Lower ambient temperatures slightly increased the pitch’s viscosity—like refrigerating honey and expecting it to pour at the same speed. It won’t.
Legacy, Recognition, and Scientific Curiosity
The experiment gained global attention under John Mainstone, though neither he nor Parnell saw a drop fall.
- Awarded the Ig Nobel Prize in Physics (2005).
- Celebrated for making people laugh first, then think deeply.
Beyond novelty, it remains a powerful lesson in long-term observation and material science—a reminder that some truths reveal themselves only over generations.
TL;DR: The 99-year-old Pitch Drop experiment has produced just nine drops, with intervals growing longer due to reduced pressure and cooler temperatures after air conditioning installation. The tenth drop is forming, highlighting how even tiny environmental changes can reshape physics over decades.
AI summary:
- Pitch Drop experiment started in 1927
- Only 9 drops observed; 10th forming
- Pitch is extremely viscous liquid
- Drop intervals increasing over time
- Cooling from AC slowed experiment further
