At the Houston Museum of Natural Science they recently made a disturbing discovery: their Foucault pendulum had stopped swinging for the first time since its installation in the 1970s. (Video, embedded below.)
While some might take this as yet another sign of the end times, here it is simply a sign that the electromagnetic system that kicks the pendulum developed a fault and will need to be fixed.
Their explainer video of this Herzstein Foucault pendulum is also worth watching, as it explains both the underlying physics and this particular pendulum’s construction. Every 48 hours the 81.6 kg heavy pendulum completes a full rotation, like clockwork, with pins along the circumference being tipped over one by one as the pendulum precesses.
Invented by [Léon Foucault] in 1851 as an experimental demonstration of Earth’s rotation using a swinging pendulum, the Foucault pendulum remains a popular physical demonstration in museums and elsewhere. Although the pendulum seems to just follow the same line, it gradually shifts its plane of oscillation, making it seem that it rotates around its attachment point…