[Phys-L] Bravais versus Foucault pendulum

[John Denker <jsd@av8n.com>]

Hi --

If anybody is considering building a Foucault pendulum, consider a Bravais 
pendulum instead.

Think of what you know about polarization (as applied to photons and other 
2-state systems).

A Foucault pendulum is X-polarization that gradually turns into Y-polarization.

A Bravais pendulum is RCP that proceeds at a different speed from LCP. That's 
equivalent to saying the Coriolis effect adds or subtracts from the 
gravitational restoring force.

A Foucault pendulum looks simple, but it is notoriously hard to build a *good* 
Foucault pendulum.

The Bravais pendulum has a different and reportedly milder set of problems.

I am not an expert. I have not researched this. I raise it as a hypothesis for 
you to consider.

Reference:
V M Babović and S Mekić

"The Bravais pendulum: the distinct charm of an almost forgotten experiment"

https://iopscience.iop.org/article/10.1088/0143-0807/32/4/020/pdf