Researchers announce a new state of matter: swirlons

Starling flocks, schools of fish, and clouds of insects all agree.

Researchers announce a new state of matter: swirlons
Credit: Fraser Morrison/Flickr
  • Scientists discover that active particles take a pass on Newton's Second Law.
  • Active particles exist in a "swirlonic" state of matter.
  • Swirlonic behavior explains some of the more dazzling natural phenomena such as starling swarms and shape-shifting schools of fish.

It's likely you've seen some of the fascinating videos of starling murmurations, great swarms of birds mysteriously flying as if with a single mind. These gigantic shapes swoop and swirl, shapeshifting their way through the skies while maintaining miraculous integrity. Maybe you've seen schools of fish shifting together into new shapes in likewise dazzling displays of synchrony.

How do these things happen? Consider them super-sized examples of a newly described state of matter that scientists at the University of Leicester in the U.K. are calling "swirlons." And swirlons are something new: They stand in some ways outside Newtonian law.

Swirlons are described in a paper recently published in Scientific Reports.

Lawbreakers

Credit: Wikimedia Commons/Big Think

According to Newton's Second Law, the acceleration of an object depends on both the force acting upon it and the object's mass. Its acceleration increases in accordance with the force being exerted, and as its mass increases, the object's acceleration decreases. These things don't happen with swirlons.

It appears that the Second Law relates only to passive, non-living objects at small and large scales. Swirlons, however, are comprised of active, living matter that moves courtesy of its own internal force. In this context, individual starlings are analogous to self-propelled particles within the larger swirlonic object, their flock.

Spotting swirlonic motion

Credit: Johnny Chen/Unsplash

The scientists at Leicester, led by mathematician Nikolai Brilliantov, came upon swirlonic matter as they developed computer models of self-propelled particles similar to simple bacteria or nanoparticles. They were interested in better understanding the movement of human crowds evacuating a crowded space, and these particles served as human stand-ins.

The word "swirlonic" comes from the circular direction in which the scientists witnessed their particles milling about in clusters that operated together as larger quasi-particles.

"We were completely baffled," says Brilliantov, "to witness how these quasi-particles swirl within active matter, behaving like individual super-particles with surprising properties including not moving with acceleration when force is applied, and coalescing upon collision to form swirlons of a larger mass."

Brilliantov tells Live Science, "[They] just move with a constant velocity, which is absolutely surprising."

It's not the first time such behavior has been seen, but the first time it's been identified as a distinct state of matter. Says Brilliantov, "These patterns have previously been observed for animals at different evolution stages, ranging from plant-animal worms and insects to fish, but rather as singular structures, not as a phase which borders other phases, resembling gaseous and liquid phases of 'normal' matter."

The researchers also saw that swirlonic particles operate on a sort of "one for all, all for one" basis. With passive particles such as water, different individual particles can exist in different states: some may evaporate into gas as others remain as liquid. The models of active particles, on the other hand, stuck together in the same state as either a liquid, solid, or gas.

Moving forward, and back, or up, or down together

Brilliantov and his colleagues hope to explore swirlons further, moving beyond their simulation into real-world investigations and experiments.

The researchers are also developing more sophisticated models that mimic the behavior of swirlonic animals such as starlings, fish, and insects. In these models, the active particles will have information-processing capabilities that allow them to make movement decisions as living creatures presumably do. They hope these models will reveal some of the secrets behind flocking, schooling, and swarming.

Another future possibility is creating man-made active particles that can self-assemble. Other Leicester experts agree that this is reason alone to continue researching swirlons.

In any event, says study co-author Ivan Tyukin, "It is always exciting to consider deepening our understanding of novel phenomena and their guiding physical principles. What we know to date is so much less than what there is to know. The phenomenon of the 'swirlon' is part of the tip of the iceberg of hidden knowledge. It leaves us with the eternal question: 'what else don't we know'?"

Every 27.5 million years, the Earth’s heart beats catastrophically

Geologists discover a rhythm to major geologic events.

Credit: desertsolitaire/Adobe Stock
Surprising Science
  • It appears that Earth has a geologic "pulse," with clusters of major events occurring every 27.5 million years.
  • Working with the most accurate dating methods available, the authors of the study constructed a new history of the last 260 million years.
  • Exactly why these cycles occur remains unknown, but there are some interesting theories.
Keep reading Show less

Babble hypothesis shows key factor to becoming a leader

Research shows that those who spend more time speaking tend to emerge as the leaders of groups, regardless of their intelligence.

Man speaking in front of a group.

Credit: Adobe Stock / saksit.
Surprising Science
  • A new study proposes the "babble hypothesis" of becoming a group leader.
  • Researchers show that intelligence is not the most important factor in leadership.
  • Those who talk the most tend to emerge as group leaders.
Keep reading Show less

The first three minutes: going backward to the beginning of time with Steven Weinberg (Part 1)

The great theoretical physicist Steven Weinberg passed away on July 23. This is our tribute.

Credit: Billy Huynh via Unsplash
13-8
  • The recent passing of the great theoretical physicist Steven Weinberg brought back memories of how his book got me into the study of cosmology.
  • Going back in time, toward the cosmic infancy, is a spectacular effort that combines experimental and theoretical ingenuity. Modern cosmology is an experimental science.
  • The cosmic story is, ultimately, our own. Our roots reach down to the earliest moments after creation.
Keep reading Show less
Surprising Science

Ancient Greek military ship found in legendary, submerged Egyptian city

Long before Alexandria became the center of Egyptian trade, there was Thônis-Heracleion. But then it sank.

Quantcast