Meh. Seems like a faux controversy. I looked into this a year ago when showing off some simulation software, and read that as best anyone can tell, it was proba

Meh. Seems like a faux controversy. I looked into this a year ago when showing off some simulation software, and read that as best anyone can tell, it was probably flutter.* In my reading I didn't run into anybody saying that the wind was fluctuating at the natural frequency of the bridge! I also read that the "vortex street" model for the failure had been proposed but discarded during the initial investigation. After my brief look into it, I got the idea that no serious workers have believed those wrong ideas for many decades. If some high school teachers somewhere say this was "resonance," that is correct and probably worth teaching ... it's just not resonance at the natural frequency of the bridge in still air. *Flutter is pretty cool physics. Pinch one end of a a business card, then point the free end of the card into a fan. When the airspeed gets high enough, the card should oscillate like a clarinet reed. Torque from the airstream opposes the restoring torque that keeps the bridge (or business card) level. As the airspeed grows, the net restoring force drops towards zero and the resonant frequency falls. At zero you're toast, there's no net restoring force at all.