Why Your Arms Spin to Prevent Falling When Pushed

Innovative science essayist and author Steve Mould explored the physics behind the conservation of angular momentum and torque, both of which he used to explain the involuntary, seemingly contradictory movements used to maintain balance. An example of this phenomenon is swinging arms upward into a spin to prevent a fall when pushed.

When you’re pushed, but you have no option to take a step back, you do a weird thing with your arms.  …The first thing I do is actually quite counterintuitive. I throwmy arms forwards. But if my body is pushing my arms forwards, then my arms must be pushing my body backwards, which would make the problem worse. I was confused about that for about five minutes before I realized, well, I’m not a rocket. 

By analyzing robotic mechanics and human neural processes, Mould reveals how the body and the brain collaborate to instinctively perform complex stability calculations,