American artist Jackson Pollock's paintings often clashed with the rules of the art world. But they couldn't defy（藐视，挑衅） the laws of physics, according to a multidisciplinary team of researchers from Boston College and Harvard who give quantitative¹ form to Pollock's methods and genius in the latest edition of the journal Physics Today. Quantitative analysis is a phrase few would associate with Pollock, the abstract expressionist who during the 1940s and 50s adopted the method of pouring paint onto canvas（帆布） in order to convey his artistic² vision in an interplay（相互影响） of drizzles³（细雨） , drips and splashes.

But physicist⁴ Andrzej Herczynski and art historian Claude Cernuschi of Boston College and mathematician⁵ L. Mahadevan of Harvard brought their respective expertise⁶ together to develop a quantitative portrait of Pollock's techniques, showing Pollock as an intuitive master of laws that govern the flow of liquids under gravity.

Under a scientific lens, Pollock's drizzles, drips and splashes reveal the workings of physical phenomena⁷ known as jets, drops and sheets. Each is governed by the laws of fluid dynamics⁸, which Pollock exploited through careful technique and manipulating the thickness of his pigments¹⁰（染料） and paints with water and solvents¹¹, according to the researchers.

"When Pollock is creating his pieces, he is enlisting¹² gravity as a participant – as a co-conspirator," said Cernuschi, a professor of art history. "He has to understand how pigment⁹ is going to behave under the laws of gravity. He has to anticipate what is going to happen and work accordingly. There is both spontaneity and control, just as there is in the improvisation¹³ of a jazz musician. In order to understand what is taking place with Pollock, it's essential to understand the laws of physics and the dynamics at play under the laws of gravity."

There has long been speculation¹⁴ about the role of fluid dynamics in Pollock's work, but never before an explicit¹⁵（明确的，清楚的） quantitative exploration of Pollock's primary methodology – painting with jets, or continuous flows of paint – and his less frequent use of drops and perhaps sheets, said Herczynski, laboratory director and research associate professor of physics at BC.

Herczynski and Mahadevan, Harvard's Lola England de Valpine Professor of Applied¹⁶ Mathematics and a professor of biology and physics as well, looked at Pollock's techniques and the physical aspects of paint on canvas in order to understand the forces at play. Their calculations describe Pollock's lifting and dispensing¹⁷ of paint in terms of paint load volume, viscosity¹⁸（粘度） , flow rates, gravity, and other factors.

Pollock worked by loading a stick or trowel with a far greater amount of paint than a brush holds during conventional easel painting. He released a jet of liquid to the canvas placed on the floor below. Pollock's physical technique – captured in still photographs and movies of the artist at work – reflect his efforts to control liquid-jet dynamics such as fluid instability called coiling, the circular motion of the tail of a thinning paint jet, similar to the way a stream of syrup¹⁹ "coils" on a pancake, the authors note. While Pollock may have instinctively²⁰ understood how to control these forces, it would be years later before scientists came to fully²¹ understand them in theory and practice.

"By pouring paint in this continuous jet fashion or by dripping it, he incorporated physics into the process of painting itself," said Herczynski. "To the degree that he did and to the degree he varied²² his materials – by density²³ or viscosity – he was experimenting in fluid dynamics, although his aim was not to describe the physics, but to produce a certain aesthetic²⁴ effect."