Friday, July 19, 2013

Pitch Drop the limelight

"Longest Running Laboratory Experiment Keeps on Going, Ever So Slowly"

June 18th, 2013


To view the experiment that the University of Queensland's School of Maths and Physics boasts is "more exciting than watching grass grow," you'll need to go to the display cabinet at the school's foyer. There, beneath a glass dome, you will see a funnel filled with asphalt. It doesn't seem to be doing anything other than sitting there, but do not be deceived: You are looking at the world's longest continuously running lab experiment in action.

The Pitch Drop Experiment began in 1927, the brainchild of UQ physics professor Thomas Parnell. His aim: to demonstrate that pitch—a term that includes substances such as asphalt—is not solid, but a highly viscous liquid.

To prove this, Parnell poured a heated sample of pitch into a closed funnel and let it settle, a process that took three years. In 1930, he cut off the end of the funnel, allowing the pitch to flow freely. Which it did. Very, very slowly. The first drop fell into the beaker in 1938, with the second and third drops following in 1947 and 1954. With the installation of air-conditioning in the building came a reduction in the flow rate—the eighth drop, which hit the beaker in November 2000, took 12 years and four months to fall.

Parnell died in 1948, but his experiment has since been passed onto other custodians from the university. He never saw a drop fall, but neither has anyone else—the asphalt has an exasperating tendency to drip when no one is looking. A live-streaming webcam trained on the experiment during the 2000 drop malfunctioned. The next pitch drop is expected to fall sometime during 2013.

"The Single Drip Scientists Have Been Waiting the Better Part of a Century for Just Dropped"


Josh Voorhees

July 18th, 2013


Science lovers are aflutter today over the above video, which may not look like much—OK, definitely doesn't look like much—until I tell you some people have been waiting for the better part of a century to lay eyes on the long-elusive "pitch drop" captured in the time-lapse footage you just watched with almost infinitely less of a time investment.

I won't pretend like I was even mildly aware of this until a more science-savvy colleague flagged it for me this afternoon, so I'll let Nature explain the back story behind the simple experiment that's developed its own cult-following thanks to a series of absurdly near misses in the past:

    The Dublin pitch-drop experiment was set up in 1944 at Trinity College Dublin to demonstrate the high viscosity or low fluidity of pitch — also known as bitumen or asphalt — a material that appears to be solid at room temperature, but is in fact flowing, albeit extremely slowly.
    It is a younger and less well-known sibling of an experiment that has been running since 1927 at the University of Queensland in Brisbane, which Guinness World Records lists as the world’s longest-running laboratory experiment. Physicist Thomas Parnell set it up because he wanted to illustrate that everyday materials can exhibit surprising properties.

OK, still a little fourth-period-science-class boring, I admit. But where things get good is when you learn about all the close calls suffered by researchers during the years before technology allowed them to basically just DVR the whole thing. Megan Garber, who does a truly great job capturing the excitement around the drop heard 'round the science world, details some of the more painful misses over at the Atlantic.  Those misses, in turn, were all the more painful because on average a typical professional pitch-drop experiment delivers the goods about once per decade, something that played a large part in explaining why no one had ever seen a drop before. So when you step out for 15 minutes to grab tea, as a Queensland professor did once, you're probably never going to be able to enjoy Earl Grey again after you come back to discover you managed to miss something you've been holding your breath for for the past 10 years.

Pitch Drop Experiment

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