Launch: Restored Foucault pendulum

Professor Merlin Crossley with the Foucault pendulum
Monday, 15 July, 2013

A new Foucault pendulum – an historical device which provides a striking demonstration the Earth is rotating - has been hung in the School of Physics.

Dean of Science, Professor Merlin Crossley, launched the restored pendulum in a ceremony in the foyer of the Old Main building. The shiny, 70 kilogram bob swings on a 14-metre long wire in an alcove that has been newly decorated with images of the night sky, dominated by the Milky Way.

In 1851 the French physicist, Leon Foucault, suspended his most famous pendulum from the dome of the Pantheon in Paris – using a 28 kilogram bob hung on a 67-metre long wire. The first public exhibition of a Foucault pendulum had taken place a few weeks earlier in the Paris Observatory, and many have been put in place around the world since.

Professor Crossley thanked Gary Keenan, Aurelio Epifani and Professor Joe Wolfe, from the School of Physics, for making UNSW’s new, larger pendulum - the third of these devices that has hung in the foyer.

“Physics is about the nature of things, the movement of things and the beauty of things and this pendulum reflects, quite literally, these features in the School of Physics,” Professor Crossley said.

Professor Wolfe said the Foucault pendulum was such a famous experiment because it provided unequivocal evidence that the Earth was revolving. “You set up a pendulum and it starts to precess because the Earth is rotating under it,” he said.

The trajectory of a Foucault pendulum in Sydney changes by one degree in seven minutes. For more information on Foucault pendulums see Physclips.

UNSW media contact: Deborah Smith: 9385 7307, 0478 492 060,