Pitch drop
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London lab speeds up science’s slowest experiment

In a fast-tracked update on the famous "pitch drop" experiments, students at Queen Mary University of London recently measured the viscosity of bitumen in their summer holidays.

Two long-running experiments in Brisbane and Dublin have pitch flowing through a funnel - but it only drips every ten years or so. This new design only took a month to deliver results.

Bitumen feels hard to touch, but it is less viscous than pitch. So during the 24 days captured in this time-lapse video, it begins to drip from the five flasks, each of which has a different sized opening.

It is one of a group of substances called "glasses", which exhibit an unusual combination of solid and liquid properties.

The glass we use in windows is in the same category, but it would take longer than the current age of the universe - many trillions of times longer, in fact - for it to flow or sag to any perceptible degree.

Video courtesy of Kostya Trachenko / QMUL

Go to next video: Ninth pitch drop 'expected in 2013'