The longest running known lab experiment is 85 years old and counting. In 1927, the pitch-drop experiment began when Thomas Parnell, a physicist at the University of Queensland in Australia, set it up. It sought to demonstrate that tar pitch, though brittle enough to be smashed with a hammer, is actually a liquid which flows, though slowly.
Parnell melted pitch, poured it into a glass fuel, let it cool for three years and then placed a beaker below he funnel. Eight years later, some pitch fell into the beaker. Another glop dropped into the beaker nine years afterward. The third dropping of pitch fell in 1954, after Parnell died.
In 1961, John Mainstone joined the physics department, where he spotted the experiment housed under a bell jar. The department agreed to display it for the world to see fourteen years later, in 1975. It’s still on display, in fact, it is on the internet via webcam. On November 28, 2000, the eighth drop of pitch fell – during a camera malfunction. In the entire saga of the experiment, no one has actually watched any pitch drop from the funnel! Mainstone says it is impossible to predict the next drop of pitch, although the period between drops should increase, because gases in the pitch escape and the weight of the pitch in the funnel decreases with time.
Mainstone says the experiment could continue for another 100 years, "if someone doesn’t throw it out."
Summarized from:
http://www.popsci.com/science/article/2012-01/how-long-longest-running-lab-experiment
Blog Author’s Comment
The above link is really interesting, particularly the comments below the story itself. There is a long discussion about the difference between solids and liquids, and a discussion of whether pitch and glass are liquids or not.
There is a well-referenced contention that glass is a separate state, since it has a firm molecular structure like solids but the bonds aren’t intense enough to be eternally stable. So in the very long run, glass drips and changes shape like a liquid.
Parnell melted pitch, poured it into a glass fuel, let it cool for three years and then placed a beaker below he funnel. Eight years later, some pitch fell into the beaker. Another glop dropped into the beaker nine years afterward. The third dropping of pitch fell in 1954, after Parnell died.
In 1961, John Mainstone joined the physics department, where he spotted the experiment housed under a bell jar. The department agreed to display it for the world to see fourteen years later, in 1975. It’s still on display, in fact, it is on the internet via webcam. On November 28, 2000, the eighth drop of pitch fell – during a camera malfunction. In the entire saga of the experiment, no one has actually watched any pitch drop from the funnel! Mainstone says it is impossible to predict the next drop of pitch, although the period between drops should increase, because gases in the pitch escape and the weight of the pitch in the funnel decreases with time.
Mainstone says the experiment could continue for another 100 years, "if someone doesn’t throw it out."
Summarized from:
http://www.popsci.com/science/article/2012-01/how-long-longest-running-lab-experiment
Blog Author’s Comment
The above link is really interesting, particularly the comments below the story itself. There is a long discussion about the difference between solids and liquids, and a discussion of whether pitch and glass are liquids or not.
There is a well-referenced contention that glass is a separate state, since it has a firm molecular structure like solids but the bonds aren’t intense enough to be eternally stable. So in the very long run, glass drips and changes shape like a liquid.
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