Laboratoire Interdisciplinaire de Physique

By orienting themselves to each other, fish increase their individual ability to find a preferred direction such as the direction of the flow. Indeed, in the presence of current in rivers or in the sea, a school of fish can decide to remain motionless to feed, for example. In this numerical study, we first modeled the social interactions within the school that cause the fish to align with each other.

Underwater spherical bubbles are good acoustic resonators but are notoriously difficult to stabilize. Here, to circumvent these limitations researchers from LIPhy trapped bubbles within 3D-manufactured millimetric open frames having the shape of the five Platonic solids with identical faces (4 to 20 faces). We thus obtained « Platonic bubbles », stabilized during several days. We measured their acoustic vibration under driving, and we observe that their resonance frequency obeys a simple formula in spite of the shape complexity.

How to measure objects that cannot be seen under normal circumstances? There is a way to modify the beam of a laser so that it provides exactly the information desired despite the presence of an environment that can be complex and messy. Moreover, this procedure does not work in an approximate way, but in an optimal way in the physical sense of the term: nature does not allow for better measuring accuracy with the coherent light of a laser.