"In his enforced free time, to while away the hours, Kapitsa developed an ingenious analytical approach to the problem of dynamic equilibrium. His toy example

"In his enforced free time, to while away the hours, Kapitsa developed an ingenious analytical approach to the problem of dynamic equilibrium. His toy example was the driven inverted pendulum. It is surprising how many great works have emerged from the time freed up by house arrest: Galileo finally had time to write his “Two New Sciences” after his run-in with the Inquisition, and Fresnel was free to develop his theory of diffraction after he ill-advisedly joined a militia to support the Bourbon king during Napoleon’s return. (In our own time, with so many physicists in lock-down and working from home, it will be interesting to see what great theory emerges from the pandemic.)"