Everything Everywhere Daily: History, Science, Geography & More - The Pitch Drop Experiment

Episode Date: August 1, 2020

In 1927, Professor Thomas Parnell of the University of Queensland in Brisbane, Australia created an experiment to demonstrate to his students the concept of viscosity and how some substances which appear to be solids are actually liquids. That experiment is still running 90 years later. Learn more about your ad choices. Visit megaphone.fm/adchoices

In 1927, Professor Thomas Parnell of the University of Queensland and Brisbane, Australia, created an experiment to demonstrate to his students the concept of viscosity and how some substances which appear to be solids are actually liquids. That experiment is still running 90 years later. Learn more about the pitch drop experiment, the world's longest continually running scientific experiment on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong,

long. ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. This episode is sponsored by Fluent in Three Months. Have you ever wanted to learn a foreign language and do so quickly? my friend Benny Lewis over at Fluent in three months might be able to help. Benny has spent over a decade language learning around the world. His techniques have helped tens of thousands of people learn the languages they want to learn quickly through both his online courses and his language hacking guides.

I've personally met Benny in many places all over the globe and have seen his language skills and action. He doesn't just talk the talk, he walks the walk when it comes to language learning. And I'm sure he'll be able to help you too. To sign up for his free Speak in a Week email course, just go to FluentIn3 Months.com or click on the link in the show notes. The concept of viscosity is one which mostly concerns physicists who are interested in fluid dynamics, but also one which can be easily comprehended from everyday experience. Viscosity is simply a fluid's resistance to deformation at a given rate.

Water has a very low viscosity. Olive oil has a higher viscosity. Honey has a still higher viscosity and can, ketchup is usually higher than that. Basically, the longer it takes something to pour, the higher its viscosity. Viscosity can also get much higher than something like ketchup. Things like peanut butter and toothpaste are technically fluids with very high viscosity. They're very resistant to flowing, but given enough time, they will flow.

Some things like silly putty don't seem like fluids at all, but they actually are. For example, if you put a piece of silly putty over a surface with a hole, it will have eventually drain through the hole. And we'll take hours to do, but it will eventually go down the hole just like water in extreme slow motion. At the very top of the viscosity scale is pitch. Also known as bitumen and asphalt, it is an organic substance with an extremely high viscosity. If you were to pick it up, it would look and feel like a rock. Pitch is both naturally occurring and manufactured. On the island of Trinidad, there's a natural lake made out of pitch. You can actually walk on the pitch lake, and you can feel yourself sinking in extreme slow motion. And I know this because

I've been there, and I've actually done it. It's a pretty cool experience. This brings us back to Professor Thomas Parnell, which I mentioned in the intro. Back in 1927, he wanted to conduct an experiment to show his students how certain substances that seem like solids were actually highly viscous fluids. What he did was take a sample of pitch and heated it. When you heat pitch, it becomes much less viscous and pours more easily. He then filled a glass funnel that was sealed at the bottom with the pitch and let it settle for three years. In 1930, after the pitch had settled, he broke the seal at the neck of the funnel to let the pitch start flowing. The funnel filled with pitch was then placed under a glass dome and put it in a display case outside the lecture hall. The pitch began flowing

out of the open end of the funnel, very slowly. Eight years after the glass was broken and allowed the pitch to flow, the first drop fell from the funnel. It took eight years for a single drop to flow out. Since 1930, the experiment has remained intact, and the funnel still sits outside the lecture hall with pitch slowly flowing out of it. In 90 years, exactly nine drops have fallen. The average time for the first seven drops was approximately eight years. However, sometime after the seventh drop in July of 1988, the time between drops increased. The eighth drop occurred in November of 2000, 12.3 years after the previous drop,

and the ninth drop occurred in April 2014, 13.4 years later. What had happened was that air conditioning was installed in the building, which lowered the average temperature the pitch was exposed to, increasing the ventilation. viscosity. The last drop actually occurred when the apparatus was moved to clean out the previously dropped pitch below, and the current hanging drop broke off. The next and tenth drop is expected to occur sometime later this decade. It is estimated there is enough pitch in the funnel to last about another 100 years. In the 90 years the experiment has been running, there have been three custodians of the experiment. Professor Parnas previously mentioned was the first. Professor John

Mainstone took over in 1961, and he, oversaw the experiment for 52 years. The third and current custodian of the experiment is Professor Andrew White, who took over the job in 2013. No one has ever actually seen any of the nine drops take place. They have happened in the middle of the night or at times when no one was looking. In 2005, the experiment was awarded the Ig Nobel Prize in Physics, which is a parody of the Nobel Prize. The Guinness Book of World Records has also awarded it the record for the world's longest continually running laboratory experiment. Today there is a webcam hooked up so you can actually watch the pitch drop in real time.

I would say it's like watching grass grow or watching paint dry, but both of those things are actually much, much faster than flowing pitch. After the eighth drop of the pitch in November 2000, they were finally able to calculate its viscosity. The value they came up with was that it was 230 billion times more than. viscous than water. It should be noted that the University of Queensland is not the only long-term pitch drop experiment in the world. In October 1944, a similar pitch experiment was started at Trinity College in Dublin. No one is sure who started the experiment, and it was forgotten for decades,

with dust accumulating on it and no one paying attention to the pitch drops. In April 2013, they noticed a drop was forming, so they moved the apparatus and set up a webcam. And at 5 p.m., on July 11, 2013, the camera captured the first ever pitch drop. They calculated their pitch was 30 billion times more viscous than water. There are a few other long-term scientific instruments still in operation. The most notable is the Oxford Electric Bell at Oxford University. It is a battery that's connected to a clapper, which alternates between two charged bells. When it touches one bell, the charge switches and it moves to the other bell.

The battery was set up in 1840, and it is a battery. been running for 170 years straight. It has been estimated that the bell has produced 10 billion rings since it started. Eventually, the battery will run out, but each movement of the clapper is extremely small, as is the amount of charge involved. In 1872, Lord Calvin set up an apparatus in Glasgow University to test the diffusion of liquids. He created two 17-5-foot-tall glass tubes in a lecture theater. In one, he put a blue copper sulfate solution at the bottom and then topped off the tube with water. In the other, he put water at the bottom and then topped it off with a red-colored alcohol. The tubes have been left alone for 148 years. Renovations to the room have built a

walled-off compartment for the tubes and no one has touched it. It isn't really an active experiment as there's no custodian and no one is taking measurements, but the liquids are still diffusing. There is one more pitch drop experiment that was rediscovered at Aberystwyth University in Wales. The experiment actually dates back to 1913, before the Queensland experiment, but it was completely forgotten for over a century. The pitch in this experiment hasn't budged in over a century. It has only moved a few millimeters and hasn't even gone out of the funnel yet. It's estimated it might take 1,300 years for the first drop to fall. Executive producer of Everything Everywhere Daily is James McAula.

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