In today’s lecture we’re going to be talking about experiments, and I thought it might be
interesting for you all 1. _____ learn about the world’s oldest continuously running laboratory
experiment 2. _____ is still going today. In fact, it holds the Guinness World Record for 3. _____ the
longest-running experiment. This experiment began in 1927 and has been going 4. _____ since.
It’s called the ‘pitch drop’ experiment and it was created by Professor Thomas Parnell at the
University of Queensland, Australia. Parnell was the university’s first physics professor, and he
wanted to show in this experiment that everyday materials, 5. _____ as pitch, can have quite
surprising properties.
You see, when pitch is at room temperature, it feels solid. You can easily break it 6. _____
a hammer. However, it isn’t in 7. _____ solid. At room temperature, pitch is many billions of times
more viscous than water, but it’s actually fluid.
In 1927, Professor Parnell took a sample of pitch. He heated it and poured it 8. _____ a glass
funnel. He allowed the pitch to cool and settle – for three years. He then turned the funnel
upside 9. _____ and cut the top off it.
Since 10. _____, the pitch has slowly dropped out of the funnel. How slowly? Well, the first drop
11. _____ eight years to fall. It took another forty years for 12. _____ five drops to fall. Today it’s
been almost 90 years since the experiment started. Only nine drops 13. _____ fallen from the
funnel. The last drop fell in April 2014 and the next one is expected to fall in 14. _____ 2020s.
The experiment has 15. _____ tragic story associated with it. Professor Parnell died 16. _____ seeing a pitch drop. His replacement, Professor John Mainstone, became responsible for the pitch
drop experiment from 1961. He held the job for 52 years, and missed seeing the drop 17. _____
three times – by a day in 1977, by just five minutes in 1988 and finally in 2000, when the
webcam that was recording the experiment suffered a power outage for 20 minutes, during
18. _____ time the pitch dropped.
The pitch drop experiment is something we can all participate 19. _____ now. There’s a live web
stream that allows anyone to watch the glass funnel and wait for the fateful moment. A similar
experiment to the Queensland pitch drop was set 20. _____ in Dublin, and the video of the moment
the pitch actually dropped went viral on the internet. It’s interesting to see how a very slow
event can spread news so quickly.