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French Physicists Explore The Science Of A Cowboy's Lasso

How does it twirl? Why does it loop? An American cowboy might take it all for granted. But a French team has explored how the laws of physics can explain this common thread.

Lasso science
Lasso science
David Larousserie

PARIS — Cowboys are alive and well, and not only in the United States. You can find three of them twirling their lassos in the middle of a Parisian physics laboratory.

Basile Audoly, Pierre-Thomas Brun and Neil Ribe, all French scientists, made the trip to Denver, Colorado in March to present their theory of “lasso art” at the annual meeting of the American Physical Society.

Audoly, Brun and Ribe call it “art,” as they chose to explore the aesthetic aspect of lassoing rather than its professional dimension — catching cattle. The scientists wanted to understand how one can perform such tricks as the “flat loop” — a horizontal spinning loop — the “vertical loop” or the well-known but complex “text skip,” in which the cowboy jumps back and forth through a large vertical loop.

The researchers pushed scientific precision to another level. They first consulted with Jesus Garcilazo, a Mexican professional working at Disneyland Paris. After initial trials with a small chain and some tape to close the loop, they finally bought a proper rope in the U.S.

Audoly, Brun and Ribe then built a rather basic robot able to spin a lasso. They found in Denver another cowboy to work with: Craig Ingram, now popular for his prowess in lasso tricks.

But the scientists’ interests go much further than the art of lasso spinning. The three of them are all specialists in “elastic and hanging threads.” This includes hair, trickles of honey, transatlantic submarine communications cable or even DNA molecules. Lassos are another example of this type of threads, with the distinctive feature of having a closing loop.

“It’s a well-known object yet there was no scientific research on it,” said Pierre-Thomas Brun, one of the researchers. "There is a fundamental interest in understanding why such different objects behave in similar ways.”

[rebelmouse-image 27087933 alt="""" original_size="800x600" expand=1]

How does it twirl? — Photo: Véronique PAGNIER

The researcher explained that the answers lie within the objects’ geometry and its relation with their dynamics. "The lasso gives us the opportunity to better understand these threads," he said.

After hours of practice — manually and with the robot — the French scientists confirmed the theory that three shapes appear depending on the rotation speed. The first one is a curved shape that looks like an elbow, in which the loop is closed and horizontal. The second one makes the rope look like a clothes hanger, with an open but vertical loop. The last one — the one researchers seek to achieve — is called “the flat shape,” in which the loop is open and horizontal.

In the end, the amplitude of the movement doesn’t matter much. The other factor to take into account is the length of the loop, which can be adjusted with a slipknot. The study predicts the favorable conditions needed to create the “flat loop”: Spin the rope twice per second, with at least 70% of the rope in the loop. "The typical beginner’s mistake is to start with a loop that is too small," Brun said. Don’t expect to make it work with less than a rotation a second. Another trick is to frequently untwist the rope with a small wrist movement, so as to prevent it from being completely tangled like old telephone cords.

“We didn’t do all of that just for pleasure. The most basic equations, which aren’t that complicated to pose, are difficult to solve in practice and remain poorly understood,” Brun said. “The lasso became a model problem to help us ask the fundamental questions. The study enables us to learn more about these equations.”

“The philosophy behind it is to use simple objects to get a sense of what is important in the abstract equations that describe them,” said Dominic Vella, a lecturer at Oxford University. Instead of catching cattles, the scientists caught realities that, until now, had eluded them.

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Geopolitics

Senegal's Democratic Unrest And The Ghosts Of French Colonialism

The violence that erupted following the sentencing of opposition politician Ousmane Sonko to two years in prison left 16 people dead and 500 arrested. This reveals deep fractures in Senegalese democracy that has traces to France's colonial past.

Image of Senegalese ​Protesters celebrating Sonko being set free by the court, March 2021

Protesters celebrate Sonko being set free by the court, March 2021

Pierre Haski

-Analysis-

PARIS — For a long time, Senegal had the glowing image of one of Africa's rare democracies. The reality was more complicated than that, even in the days of the poet-president Léopold Sedar Senghor, who also had his dark side.

But for years, the country has been moving down what Senegalese intellectual Felwine Sarr describes as the "gentle slope of... the weakening and corrosion of the gains of Senegalese democracy."

This has been demonstrated once again over the last few days, with a wave of violence that has left 16 people dead, 500 arrested, the internet censored, and a tense situation with troubling consequences. The trigger? The sentencing last Thursday of opposition politician Ousmane Sonko to two years in prison, which could exclude him from the 2024 presidential elections.

Young people took to the streets when the verdict was announced, accusing the justice system of having become a political tool. Ousmane Sonko had been accused of rape but was convicted of "corruption of youth," a change that rendered the decision incomprehensible.

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