A new state of matter has been discovered by physicists at the University of Leicester.
In recent years, active self-propelled particles have received increasing interest among the scientific community. Examples of active particles and their systems are numerous and very diverse, ranging from bacterial films to flocks of birds or human crowds. These systems can demonstrate unusual behavior, which is difficult to understand or model.
To this end, large-scale active particle models were being examined by experts at Leicester in order to understand the basic principles of active particle dynamics and apply them in an evacuation strategy scenario for customers in crowded locations. Unexpectedly, the “super particles” grinding in a circular motion were found by Leicester physicists, who later coined the phenomenon as “whirlwind”.
The “whirlpool” – a new state of active matter – exhibited a stunning behavior whereby instead of moving with acceleration, the groups of quasi-particles moved with a constant speed, proportional to the applied force and in the same direction as the force. This conduct apparently violates Second Newton’s Law, currently taught in UK high schools.
Professor Nikolai Brilliantov, who led the research at the University of Leicester, said: – “We are completely baffled to witness how these quasi-particles rotate within the active matter, behaving like individual super-particles with surprising properties, including not moving with acceleration. when force is applied, and coalescing in the collision to form swirls of a larger mass.
“These patterns have already been observed in animals at different stages of evolution, from plant-animal worms and insects to fish, but rather as singular structures, not as a phase that borders other phases, resembling the gas and liquid phases of ‘normal’ matter. “
Professor Ivan Tyukin, Director of Research in Applied Mathematics, said: “It is always exciting to consider deepening our understanding of new phenomena and their guiding physical principles. What we know so far is much less than there is to know. The “whirlwind” phenomenon is part of the tip of the iceberg of hidden knowledge. This leaves us with the eternal question: ‘what else do we not know’? “
The world of active particles has many practical applications, including in the cutting edge fields of artificial intelligence, spatial data and robotics. Since one of the possible practical applications of active particles could be self-assembly, experts at the University of Leicester agree that it is essential that physicists continue to push for discoveries based on simulation work. This will ensure that, in real life, materials, substances and groups work in a reliable, expected and predictable manner, without inevitable uncertainties.
Reference: “Swirlonic state of active matter” by Nikolai V. Brilliantov, Hajar Abutuqayqah, Ivan Yu Tyukin and Sergey A. Matveev, October 8, 2020, Scientific Reports.
DOI: 10.1038 / s41598-020-73824-4