The slowest experiment in the world

At a university in Australia there is a funnel of pitch —the black tar from the roads— that has been dripping since 1927.

Pitch looks like a solid: if you hit it with a hammer, it shatters. But it is really a liquid so, so thick that it takes years to form a single drop. In almost a century only nine have fallen.

The most astonishing part: for 86 years no one managed to see a single one fall. The professor who set it up died without ever seeing it; his successor missed a drop by stepping out for a cup of tea. Until, in 2014, a camera finally caught it.