A lecture about an experiment

A lecture about an experiment

Listen to the lecture about a science experiment to practise and improve your listening skills.

Do the preparation task first. Then listen to the audio and do the exercises.


In today's lecture we're going to be talking about experiments, and I thought it might be interesting for you all to learn about the world's oldest continuously running laboratory experiment that is still going today. In fact, it holds the Guinness World Record for being the longest-running experiment. This experiment began in 1927 and has been going ever 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, such as pitch, can have quite surprising properties.

You see, when pitch is at room temperature, it feels solid. You can easily break it with a hammer. However, it isn't in fact 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 into a glass funnel. He allowed the pitch to cool and settle – for three years. He then turned the funnel upside down and cut the top off it.

Since then, the pitch has slowly dropped out of the funnel. How slowly? Well, the first drop took eight years to fall. It took another forty years for another five drops to fall. Today it's been almost 90 years since the experiment started. Only nine drops have fallen from the funnel. The last drop fell in April 2014 and the next one is expected to fall in the 2020s.

The experiment has a tragic story associated with it. Professor Parnell died without 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 fall 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 which time the pitch dropped.

The pitch drop experiment is something we can all participate in 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 up 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.

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Submitted by Echo1 on Sat, 24/10/2020 - 08:21

The Michelson-Morley experiment. The main objective of this experiment was to detect the luminiferous ether which was believed to be the medium wherein light and other electromagnetic waves propagate. In this experiment, they measured the speed of light in many different angles and speculated that they should measure a maximum and a minimum value for the speed of light. The maximum value of the speed of light will be measured when the light is travelling within the ether, and the minimum value can be measured when the light is travelling against the motion of the ether. However, no differences in the speed of light was detected which suggested that the light does not require any medium to propagate onto. This experiment is now known as the "Best failure in science" because it is being used in a lot of practical applications specially in laboratory testings.
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Submitted by danisep on Thu, 22/10/2020 - 02:52

No I don't know a lot about any experiments, at the beginning I get the point of the experiment and I think that it's an interesting fact and we have learned something new which is great, but now this experiment is just marketing for the university I can't believe that there are people watching constantly a stream waiting for a drop.

Submitted by Ugulhan on Wed, 21/10/2020 - 16:50

I really surprised that it has been taken eight years for the first drop. I would say then the pitch drop is almost an oil substance if it could be solid but actually is a fluid. In fact, oil can be frozen at room temperature too for example oil from cotton, when you want to save oil of cotton in bottle, you can pour the warm oil into the bottle, and it can be secured in a dark room for many years. Over time, the oil will become a solid shape, but in fact, it was fluid. You can also turn the bottle upside down and cut the top off it. It is only my prediction, in school time I loved to learn physic...:) so I am saying this process.

Submitted by Denise on Thu, 01/10/2020 - 21:34

No :/. Actually I haven’t been studying that much For the past four years so I don’t know many things related with experiments or things like that but I’m glad to read this article it’s really interesting. It’s weird to think of bitumen as a solid property. Thank you for the lesson anyway ❤️
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Submitted by Hennadii on Thu, 03/09/2020 - 09:39

Of course, I've read or heard about many different experiments. Some of them are very interesting but some are completely stupid (in my humble opinion) and caused a meme about the "Britain scientists". But, telling the truth I'm not the person who interested in any kind of experiments that much to keep them in mind. So it's a bit hard for me to give a proper answer to this question. In his case, let me say some words about the "Pitch drop experiment". I think it was quite interesting in 1927 to start this experiment - to show others that the common material which everybody took like something solid turn out to be liquid. And the very first drop (maybe the first two or three) was a great achievement for all who took part in this experiment. But now, all this "drops waiting" through the years looks like something stupid and absolutely senseless. This experiment evolved into the university tradition and doesn't belong to science anymore. Of course, it's only my opinion and I admit someone can think differently.

Submitted by fahri on Wed, 05/08/2020 - 02:49

Dear team. From the lesson above. Pitch is (BLACK SUBSTANCE) a thick, black substance that was used in the past to make wooden ships and buildings waterproof. The question: Is definition right in that context??? What's the urgency of picth drop in our live??? I think it's just waste our time to see it. Thank you very much for your explanation and answer.

Hello fahri,

Yes, that's correct. Pitch is an extremely thick liquid - so thick it appears to be a solid - and that is why it drips so slowly.



The LearnEnglish Team

Submitted by nona nasr on Wed, 10/06/2020 - 22:08

I don’t understand The experiment has a tragic story associated with it. Professor Parnell died without seeing a pitch drop.

Hello nona nasr,

Professor Parnell set the experiment up and it would have been nice if he had seen the pitch drop, but unfortunately he did not. This is why the story has a sad (tragic) side.



The LearnEnglish Team