(ANSA) - Foucault's Pendulum, one of the most famous scientific experiments in history, will be recreated in Bologna on Saturday with the help of Italian philosopher and author Umberto Eco.
The experiment, whose name provided the title for one of Eco's best-selling novels, proves that the earth turns on a north-south axis, completing one rotation each day.
It was first performed by French physicist Jean Bernard Foucault in Paris's Pantheon in 1851. He hung a 28-kg sphere
at the end of an 11-metre pendulum from the ceiling and gave it a push.
The pendulum swung backwards and forwards across a point on the floor for several hours, making lines in piles of sand
left there for this purpose. Instead of always following the same track, as non-scientists expected, the lines gradually twisted around.
The experiment finally demonstrated unequivocally something that physicists had long worked out but been unable
to prove - that the earth spins as it flies through space. Some 155 years later, Eco will set a similar pendulum in motion in Bologna's basilica of St Petronas. He will introduce the stunt with the same words that Foucault used in Paris: "You are invited to witness the earth turn around."
The recreation of the experiment is part of a four-day initiative organised by Bologna city hall and the city's university in a bid to help popularise scientific studies. Apart from the link with Eco, one of Bologna's most famous sons, there is another reason why the city is putting on the experiment again.
Researchers have shown that 61 years before Foucault succeeded in wowing crowds in Pars, a Bologna monk had tried
to demonstrate the same principle in his city in a slightly different way. The monk, identified as Abbot Guglielmini, dropped
weights from the top of one of Bologna's distinctive towers at different times of day, hoping that their paths would show
the earth twisting.
But he made mistakes in his calculations and apparently no one could understand his explanation of the experiment anyway.
It was not until Foucault had the idea of a huge pendulum that the world at large could actually see what Isaac Newton had demonstrated in theory more than a century earlier. Foucault was born in 1819, the son of a French publisher. He showed early skill in making mechanical toys, studied medicine, but then shifted to physical sciences. He became one of the most versatile scientists of all time. A year later, he also invented the gyroscope, a device that incorporates and demonstrates the properties of
revolving bodies.
