Fig. 3.

Characterising the dynamics of pattern formation. Time evolution of normalised bacterial density (as measured by DDM, see Methods) inside squares of different dimensions L (inset, Fig. 2f), starting from a diffusive state and b uniformly swimming state. Inset: data plotted against time; main plots: data collapse when scaling time by $\sqrt{L_0\mathrm{∕}L}$ in a and L₀/L in b (both with L₀ = 540 μm). c Scaling of ‘box emptying times’ t_D, t_S, as well as ${\overline{v}}_{\mathrm{D,max}}$ (the maximum swimming speed reached when starting with diffusive cells) with square size L. d Shift of the peak position over time in the dark stripe (Fig. 2h); dashed line = power law fit of slope 0.5. Error bars in a, b are SE of the q-averages and in c, d the SD estimates returned by the fitting routines