Fish school, insect swarms and birds fly in murmurs. Now new research finds that this kind of group behavior at the most basic level forms a new kind of active cause, called a swirlonic state.
Physical laws such as Newton’s second law of motion – which states that as the force exerted on an object increases, its acceleration increases, and that the acceleration decreases as the mass of the object increases – this applies to passive, non-living matter, which varies from atoms to planets . But a large part of the matter in the world is active matter and moves under its own, self-directed, power, said Nikolai Brilliantov, a mathematician at the Skolkovo Institute of Science and Technology in Russia and the University of Leicester in England. . Living things as diverse as bacteriabirds and humans can interact with the forces that occur on them. There are also examples of non-living active matter. Nanoparticles, known as “Janus particles”, consist of two sides with different chemical properties. The interaction between the two sides creates a self-propelled movement.
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To investigate active matter, Brilliantov and his colleagues used a computer to propel particles that could propel themselves. These particles were not consciously interacting with the environment, Brilliantov told WordsSideKick. Rather, they were more similar to simple bacteria or nanoparticles with internal energy sources but without information processing capability.
The first surprise was that this active case acts very differently from passive matter. Different states of passive matter can coexist, Brilliantov said. For example, a glass of liquid water may gradually evaporate in a gaseous state while still leaving liquid water behind. The active cause, on the other hand, does not exist in different phases; it was all solid, liquid or gas.
The particles also grouped together as large conglomerates, or quasi-particles, ground in a circular pattern around a central void, like a whirlpool of sardines. The researchers call these particle conglomerates ‘vortices’ and call the new state of matter they form a ‘vortex-shaped state’.
In this swirlonic state, the particles exhibit bizarre behavior. For example, they violated Newton’s second law: when a force was applied to them, they did not accelerate.
“[They] just moving at a constant speed, which is absolutely amazing, ‘Brilliantov said.
The simulations were basic, and experimental work with active matter in the real world is an important next step, he said. Brilliantov and his colleagues also plan to do more complex simulations using particles with active materials with information processing capability. It looks more like insects and animals and helps to reveal the physical laws regarding schooling, swarming and current. Ultimately, the goal is to create self-assembled materials from active materials, Brilliantov said, making it important to understand the phases of this type of matter.
“It is very important that we see the nature of active matter” is much richer than that of passive matter, Brilliantov said.
The research was published in the journal in October 2020 Scientific reports.
Originally published on Live Science.