Foucault Pendulum at the Pantheon: Physics and Setup

The Foucault pendulum at the Pantheon converts the Earth’s rotation into a gentle precession visible to all. Suspended under the dome, it embodies Paris’s union of science, architecture, and spectacle.

🧪 Period and Precession

For a pendulum of length (L) near Paris’s latitude (arphi approx 48.8^circ):

$$ T = 2pisqrt{rac{L}{g}}, qquad Omega_ ext{precession} = Omega_oplus,sinarphi $$

• Period (T): sets the swing time.
• Precession (Omega_ ext{precession}): rate at which the plane of swing rotates.

🔧 Setup and Damping

• Long cable reduces angular velocity and noise.
• Low-friction pivot minimizes parasitic forces.
• Target markers visualize slow precession for visitors.

👀 Public Demonstration

• Interpretive panels connect math to motion.
• Guided viewing—watch drift over tens of minutes.
• Photography: the pendulum becomes a time instrument.

Science thrives when precision meets public curiosity.

[^history]: The original experiment dates to 1851; replicas continue the tradition.