Happy Nice Mall

Early autumn afternoons in the temperate world, midges now gather for their flock: clouds of tiny flies, wings illuminated like many sparks by the sun, spin in intricate patterns too fast for the eye to follow, but leave a mental trail. Order. It’s not perfect order, it’s more than chaos.

To scientists who have studied such swarms, this impression of order is true: In the movements of midlife, you can find mathematical signatures of features beyond what one might expect from an insect cloud. As a group, they behave like liquids or gases, and even exhibit properties of ‘criticality’, the enigmatic stage in which the radical transformation of matter from one state to another happens in the blink of an eye.

A physicist at the Complex Systems Institute in Rome, Dr. “Collective correlation can free the system from its microscopic details,” said Andrea Cavagna. A flock is much more than their middle age.

A theoretical physicist at La Sapienza University in Rome, Dr. Cavagna and his partner, Dr. Irene Giardina studied herds of starlings before turning their attention to midges. Using high-speed video cameras to measure the trajectory of each swarming bird, called a flocks of starlings, researchers discovered in 2009 that when a starling changes direction or speed, the birds closest to them change, and the birds closest to them, in turn. them. Each starling in a purr thus ties together, no matter how far.

In the language of statistical mechanics, this is known as a scaleless correlation. This is a property of criticality – how particles in a pile of hot iron harmoniously change direction and form a magnet when exposed at the point where the liquid becomes gaseous or cooled to a certain temperature.

This year, Dr. Cavagna and Dr. Giardina’s work on starlings brought them a prestigious award. Max Delbrück Prize in Biological Physics. And in the early years of their research, as they took their young children to the parks of Rome, they marveled at the swarms of midges flying across the grass and became curious about them, too.

The swarms of midges didn’t seem to be as tightly coupled as the purrs, but the insects didn’t seem to move completely independently, either. Dr. “We had the idea that the same kind of model could be used to describe midge swarms,” ​​said Giardina.

The researchers trained their cameras on flocks—no small feat given the disappearance of the flocks and the intrusive curiosity of those around—and like starlings in a flock, middle ages in a herd are collectively related.

They do not all go in the same direction in near-perfect synchrony, nor is the degree of correlation as strong as in starlings. Within a flock there may also be subgroups moving in different directions, in which individuals move from one subgroup to another – hence disorganization. However, middle ages are all mixed together.

The researchers also found that as flocks increase in size, they become more intense and midges’ flights become more closely related. This is likely a function of how midges respond to the sound of their neighbors’ buzzing wings, allowing them to maintain an optimal degree of correlation.

Dr. “It’s like the system is self-organizing to get the maximum possible response,” said Giardina. Dr. Cavagna described it as a way of “highest precision surfing” that allows for sudden, coordinated movements.

Dr. “The closest models in physical systems are magnets,” Cavagna said; that is, the sudden bulk change in particle orientation just before magnetization. However, he stressed that the boiling midges were only near that critical point, not just near it.

That could be a physical limitation, he said. True criticality only occurs on systems with many more units than in a swarm. One gram of iron magnet contains roughly 10,000,000,000,000,000,000,000 iron atoms, while a suitably sized swarm of midges contains only a few hundred.

It’s also possible that reaching criticality would be disastrous for them, making the flock hypersensitive to any ailment, blowing air, or whatever the midge equivalent of a sneeze is. A physicist at the University of Granada in Spain, who closely followed the research, Dr. “The best trade-off is to be close to the critical,” said Miguel Muñoz. “You benefit from sensitivity, but you are not too close because if you are too close you will react to anything.”

The potential benefits of swarming are evident in purrs, whose synchronized twists and turns can help starlings. avoiding predators.

Swarms of almost entirely male midges function for reproduction as females enter and mate in midair. Perhaps working at a critical level is conducive to a taste of romance? This is unknown. Dr. It’s also possible that herd traits aren’t adaptive, but simply “a side effect of the math,” Cavagna said.

Dr. Munoz, Dr. Cavagna and Dr. He considers Giardina’s findings “convincing,” but some scientists are taking the issue. Stanford University physicist Dr. Nicholas Ouellette and colleagues found in their own study of captive midges that correlations did not emerge quickly. when did they appear, the correlations did not fit the criticality framework.

The herds were intriguing nonetheless. In a 2017 article in Physical Review Letters, Dr. Ouellette and her co-authors described them as containing midlife whose flight patterns made an impact. condensed core surrounded by a layer of vapor.

When the team separated the visual spots on which a swarm had formed, the flock split in two. (In nature, the markings could be stumps or leaves; in the lab, they were pieces of paper.) In doing so, the flocks behaved like a solid, not like a liquidA theoretical biologist at Rothamstead Research in Britain, Dr. “It appears to be under increasing tension before it finally ruptures,” said Andrew Reynolds.

Dr. “Different stimuli can cause different behaviors,” Reynolds said. He was not involved in the Stanford experiment, but Dr. He collaborated with Ouellette on others, including a lab swarm. swayed and crushed Like Jell-O. Earlier this year, Dr. Ouellette and her collaborators described what the herds looked like. governed by the laws of thermodynamics.

Such findings suggest that a swarm can be understood as a singular entity rather than a collection of individual insects, much like a quartz crystal is perceived as a separate object rather than trillions of atoms. Dr. “You’re used to thinking of it as one thing because you can’t see what it’s made of,” Ouellette said. “These herds have well-defined material characteristics that are characteristics of the group, not individuals.”

As for disagreements over correlation and criticality, these will eventually be resolved with further research. It’s also possible that both groups were right: Maybe swarms of midges could exist in all the forms the researchers described, depending on size and condition.

Wherever this scientific dust settles, one can appreciate how wonderful human swarms are and the compelling glimpses they provide to the principles underlying seemingly disparate phenomena. Dr. Muñoz’s interest in research led to Dr. criticality in neural networks and cellular function; There may be similarities between the dynamics of the swarms and the brain’s way of converting cellular stimulation into an image, or a genome expressing instructions in its DNA.

“Criticality can be a unifying principle,” he said, which produces excellent coordination and complexity from simple components and has been used many times by evolution. And even if the swarms aren’t nearly as critical, the links are still deep.

Dr. Reynolds noted that researchers compared flocks over a long period of time. to self-gravity systemsby comparing the forces that help them maintain harmony on a windy day to the forces that hold the planets together. In a recent paper, he compared swarms to collecting dust, gas, and plasma. in interstellar clouds.

Dr. “Now whenever I see a swarm of midges, I see great beauty and delicacy,” Reynolds said. “They stop me in my tracks.”