Researchers in Japan have engineered a particle system that temporarily ignores Newton's third law of motion. By manipulating microscopic particles in water using an electric field, the team observed a non-reciprocal "chasing" behavior that defies traditional physics.
The hour-long defiance of 10,000 particles
In a study published in Physical Review Letters, a team of Japanese physicists successfully created a system of over 10,000 particles that violated the fundamental principle of action and reaction for a duration of one hour. Newton's third law typically dictates that passive particles must exert equal and opposite forces on one another. however, as the report says, this specific system saw passive particles spontaneously forming pairs and "chasing" each other within a liquid environment.
This phenomenon represents a significant departure from classical mechanics. By breaking the symmetry of action-reaction, the researchers demonstrated that matter can exhibit unusual collective motions and self-organization. Yutaka Sumino,a co-author of the study, noted that this breaking of symmetry is the key to generating these new types of movement in matter.
How alternating electric fields and electrodes drove the 'chase'
The Japanese research team achieved this result by suspending microscopic particles in water and confining them between specially fabricated electrodes. According to the report, the physicists then applied an alternating electric field, which caused larger particles to attract smaller ones. This specific interaction created a self-propelled motion where the particles did not push back with equal force, but rather followed one another.
The importance of particle diversity became clear when the team attempted the experiment with particles of only one size. In that scenario, the particles exhibited reciprocal interactions, meaning Newton's third law held firm, and the particles organized themselves into a static crystal structure. This contrast proves that the "chasing" behavior is dependent on the interaction between differing particle sizes under the influence of the electric field.
From biological systems to programmable microrobotics
The ability to create non-reciprocal motion echoes patterns often seen in nature, where biological entities move with intent rather than simple passive reaction. Yutaka Sumino suggests that similar interactions may occur in biological systems, where cells or organisms organize themselves through complex, non-symmetric forces. By replicating this in a lab, the team is providing a blueprint for how synthetic systems might mimic life-like movement.
Beyond biological mimicry, this discovery has immediate implications for the development of programmable materials. if scientists can control how particles "chase" or avoid one another, they could potentially design microrobotic systems capable of autonomous assembly or targeted delivery within a fluid environment. This shifts the paradigm from static material science to dynamic, programmable matter.
The mystery of permanent clumping and long-term stability
Despite the success of the experiment, several questions remain regarding the stability of these systems. The report notes that the particles with differing sizes never clumped together permanently; instead, they gathered and then split apart. It remains unclear why this cycle occurs or if there is a way to stabilize these "chasing" pairs for longer than the one-hour window observed in the study.
Furthermore, the source focuses exclusively on the findings of the Japanese team without providing external peer critique or alternative theories on why the action-reaction symmetry broke. It is also unknown whether this effect can be replicated with larger particles or in environments other than water, which limits the current understanding of how universal this "law-defying" behavior truly is.
Comments 0