Monday, October 21, 2013

Even More Pitch Experiments

While the Pitch Drop Experiment at the University is billed by both the Guinness Book of World Records and it's own webpage [1] as the longest running experiment, ScienceNews reported last week of other experiments that are similar in nature and one that is clearly the winner of the longest running experiment. I loved the article as I was not aware of any of these other experiments.

Two of the experiments are the design of Lord Kelvin. The first involves a layer of pitch in a shallow, broad dish. Corks were placed under the pitch and bullets were on top. Over time, the corks floated to the top and the bullets sank. What I find most fascinating was that this was used as a model for the now-deposed concept of aether which permeated the universe.
"Pitch was the only earthly material Kelvin knew of that could simultaneously behave as a solid and a fluid. He and other physicists of his era believed that a similar substance called the ether permeated the cosmos. Ether needed to be rigid enough to propagate rapidly oscillating light waves, yet fluid enough for planets and other objects to travel through it. Pitch was a great analog."
(The concept of aether was finally set aside for good when Einstein developed the concepts of relativity. While this experiment may have been the first time that rheology and cosmological physics crossed paths it wasn't the last. The same matrix calculations that Einstein developed for his Theory of Relativity are used today in many rheological equations.)

The second experiment, also attributed to Lord Kelvin, was an artificial glacier, in which pitch was placed at the top of a ramp and slowly crept down it over time, much how a glacier slowly flows down a moutainside or other slope.

But the last experiment described by ScienceNews tops all of this, even a couple of other experiments [2] that aren't mentioned.
"Despite its head start, the newly rediscovered 1914 pitch experiment in Wales has not produced a single drop. The funnel stem is about 80 millimeters long, Aberystwyth lab technician Stephen Fearn says, yet the pitch has descended a mere 6 millimeters in the century since physicist G.T.R. “Taffy” Evans set it up. At that rate, the pitch won’t emerge from the funnel — let alone form a drop — for another 1,300 years. It’s unclear what type of pitch Evans used and why it flows so slowly."
Obviously a much more viscous pitch, but still rheology trumps all as there is sufficient evidence from the last 99 years that it is flowing. As they say, "When the going gets tough, the tough get rheology".

[1] Be sure to check out the high res version!

[2] Including another one from Lord Kelvin - what was it with this guy and long-running experiments?

No comments: