Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
(A to D) Snapshots of the individual particle velocities for the four major phases: gas (f = 20 Hz) (A), flocking (f = 30 Hz) (B), vortex (f = 40 Hz) (C), and reentrant flocking (f = 50 Hz) (D) (see also movies S1 to S8). Individual flocks in (B) and (D) are accented by light colors. (E to H) Magnitude of the corresponding coarse-grained velocity fields. Scale bars, 1 mm.
