Physicists model flocks of birds in flight and bacteria swimming in a pool of nutrients to understand the emergence of collective behaviour. These are examples of active matter systems, where individual elements in a group consume energy from the environment to move and perform mechanical work.
A recent study identified the critical conditions under which the movement patterns in a bacterial suspension transition to a state where order coexists with chaos. Zooming in on these fluids, one would see swirling whirlpools in some pockets, interspersed with irregular and chaotic motion in others.
Reference: Kashyap, K., Kiran, K. V., Gupta, A. (2026). Emergence of local ordering and mesoscale giant number fluctuations in active turbulence. Physical Review Letters, 136(108301). https://doi.org/10.1103/ylbh-8v74