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The cheerful, striped floor covering, designed by sisters Petra and Nicole Kapitza, features a soil-resistant wool surface and cotton backing; 5 feet, 7 inches by 7 feet, 10 inches, $150.

Dr. Fort’s levitating liquid research started when he heard a talk about Kapitza’s pendulum, named after Pyotr Kapitsa, a Russian physicist who in 1951 described how, if the pendulum were vibrated up and down at the correct frequency, it would remain in the upright configuration indefinitely.

As is the case for the Stephenson–Kapitza pendulum6 and the Chelomei pendulum2, the stable states of Apffel and colleagues’ vibrating system correspond to potential-energy maxima, rather than minima.

Probably the most well-documented examples are the Stephenson–Kapitza pendulum6, in which a rigid pendulum balances upside down from a vibrating point of suspension, and the Chelomei pendulum2, in which a washer that can slide along a rod seems to ‘float’ when the rod is vibrated vertically.

The first was £30,000 paid by the Soviet Union to purchase the Cavendish lab equipment of Peter Kapitza, a Soviet citizen who had been detained by the regime during a visit home in 1934 and was kept happy by its commitment to duplicate his British laboratory in Moscow.