If you sit and watch the Foucault pendulum for an hour, you will "see" that the plane of the swing of the iron ball slowly shifts anti-clockwise by about 8.4 degrees per hour. This is an optical illusion. The building is actually shifting "under" the Foucault Pendulum!

The Foucault Pendulum (support + wire + iron ball) is attached to this building. The building is attached to the Planet Earth, which rotates on its own axis about once every 24 hours. The Earth also goes around the Sun, once every year. The Sun, in turn, goes around the centre of our galaxy, The Milky Way, once every 250 million years. These are all local motions.

The Foucault Pendulum somehow ignores all these local motions! The Foucault Pendulum somehow aligns itself with the Rest of The Universe.

read more...