The basic principle of physics is that particles with opposite charges attract each other, while those with the same — repel each other. However, scientists from Oxford have discovered that under certain conditions, these rules can be broken.
In an experiment, the team placed negatively charged silica microparticles in water and found that at certain pH levels, they can attract each other to form hexagonal clusters — which seems to violate the basic electromagnetic principle that particles with the same charge should repel at any distance.
When the researchers looked at this effect using a theory of particle interaction that takes into account the structure of the solvent, they discovered a new force of attraction that could overcome electrostatic repulsion.
Instead, for positively charged particles, the interaction remained unchanged — even at different pH levels, they repelled. Interestingly, in a different solvent (the scientists used ethanol) — they eventually grouped together.
The team says that this discovery may force a serious rethinking of scientific principles, and could be used in practical chemistry for processes such as self-assembly, crystallization, and phase separation.
The study is published in the journal Nature Nanotechnology.
Source: New Atlas