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Like-charged particles attract each other, defying basic law of physics

In the realm of basic physics, Coulomb’s Law, the principle that opposites attract and like-charged particles repel has stood unchallenged for years.

However, a fascinating study from Oxford University has shattered this longstanding belief, revealing that similarly charged particles in solution can attract each other over considerable distances.

This discovery not only challenges the core tenets of electromagnetic theory but also has profound implications for various scientific and industrial processes.

When like-charged particles unite

The research, conducted by a team from Oxford’s Department of Chemistry, has uncovered that the behavior of charged particles in solution varies significantly depending on the nature of the charge and the solvent.

Specifically, they observed that negatively charged particles attract each other at large distances in water, forming tightly arranged hexagonal clusters. This phenomenon was not seen in positively charged particles under the same conditions.

Conversely, when the solvent was switched to alcohols, such as ethanol, the positively charged particles were the ones forming clusters, leaving the negatively charged particles dispersed.

The science of particle attraction

This unexpected behavior contradicts the central electromagnetic principle that like charges should repel each other at all distances. The team utilized bright-field microscopy to closely observe and track these interactions, particularly focusing on negatively charged silica microparticles in water and positively charged aminated silica particles in alcohol solutions.

Delving deeper, the researchers developed a theory considering the solvent’s structure at the interface with particles. They discovered an attractive force between negatively charged particles in water, strong enough to overcome the electrostatic repulsion and lead to cluster formation.

This interaction was found to be pH-dependent for negatively charged particles, allowing for controlled formation of clusters by adjusting the pH level. Such control was not achievable with positively charged particles in water, as their interactions remained repulsive regardless of pH changes.

Impact of like-charged particles attracting

The study’s implications are far-reaching, affecting our understanding of processes ranging from self-assembly and crystallization to the stability of pharmaceuticals and the development of diseases linked to molecular aggregation.

It suggests a fundamental shift in how we perceive interparticle and intermolecular interactions, highlighting the significant role of solvents and the electrical potential at interfaces.

Professor Madhavi Krishnan, the study’s lead, expressed pride in her team’s achievement, emphasizing the collaborative effort of graduate and undergraduate students in advancing this fundamental discovery.

“I am really very proud of my two graduate students, as well as the undergraduates, who have all worked together to move the needle on this fundamental discovery,” said Krishnan.

Sida Wang, a first author of the study, shared his fascination with the unexpected particle attraction, emphasizing the novelty and significance of their findings.

“I still find it fascinating to see these particles attract, even having seen this a thousand times,” Wang said.

Revolutionizing our understanding of particle interactions

In summary, the recent study from Oxford University dramatically shifts our understanding of charged particle interactions, challenging the longstanding principle of Coulomb’s Law that says like charges repel.

By demonstrating that similarly charged particles can attract each other under specific conditions, the research opens new doorways for scientific exploration and practical application, from enhancing self-assembly processes to revolutionizing pharmaceutical stability.

This breakthrough invites a reevaluation of fundamental physics concepts and clears a path for innovations across various fields, proving the power of collaboration and curiosity in uncovering the unseen forces that govern our world.

More about Coulomb’s Law

Coulomb’s Law stands as a fundamental principle in the study of electrostatics, offering a quantitative description of the force between two stationary, electrically charged particles.

Named after Charles-Augustin de Coulomb, who formulated the law in the 18th century, this pivotal discovery has been instrumental in shaping our understanding of electric forces and interactions.

Essence of Coulomb’s Law and charged particles

Coulomb’s Law states that the magnitude of the electrostatic force of attraction or repulsion between two point charges is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them.

This relationship not only defines the strength of the electric force but also its directional nature — attraction between opposite charges and repulsion between like charges.

Applications and implications

Coulomb’s Law has wide-ranging applications across various fields of science and engineering. It is essential in designing and understanding the behavior of electrical and electronic devices, from simple capacitors to complex integrated circuits.

Additionally, the law plays a critical role in theoretical physics, contributing to the development of theories and models that explain atomic and molecular structures.

Coulomb’s Law in modern science

While Coulomb’s Law provides a robust framework for understanding electrostatic forces, modern science has extended its principles to explore more complex interactions.

Quantum electrodynamics, for instance, delves into the quantum realm to study the forces between charged particles with unparalleled precision.

Despite these advancements, Coulomb’s Law remains a fundamental concept, grounding our comprehension of electrical phenomena in both classical and modern physics.

In summary, Coulomb’s Law is a testament to the power of scientific inquiry and mathematical description. By elucidating the nature of electric forces, it has advanced our understanding of the physical world while enabling technological innovations that shape our daily lives.

As we continue to explore the universe, Coulomb’s Law serves as a reminder of the enduring significance of foundational scientific principles.

The full study was published in the journal Nature Nanotechnology.


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