  Recent results on the effective non-local dynamics of the tachyon mode of
open string field theory (OSFT) show that approximate solutions can be
constructed which obey the diffusion equation. We argue that this structure is
inherited from the full theory, where it admits a universal formulation. In
fact, all known exact OSFT solutions are superpositions of diffusing surface
states. In particular, the diffusion equation is a spacetime manifestation of
OSFT gauge symmetries.
