For the project, they created a large-scale colloidal system containing over 10,000 colloidal particles and observed their behavior for more than an hour. To create a system with nonreciprocal interactions, the research team suspended polystyrene colloidal particles measuring 1 and 1.5 micrometers in radius in water. Nonreciprocal interactions in a colloidal system containing over 10,000 particles. As a result, this imbalance produced nonreciprocal interactions between particles of different sizes. The team said similar nonreciprocal interactions could occur in biological systems, like cell colonies and groups of animals.