Blast wave

A blast wave is a type of Shock wave produced by an intense, localized energy release — an explosion, a supernova, or a nuclear detonation — that expands spherically into a surrounding medium, compressing and accelerating the material it encounters. Unlike a planar shock, which maintains constant strength as it propagates, a blast wave decays: its pressure and velocity drop as the energy is distributed over an ever-larger spherical surface, and the shocked material eventually returns to the ambient state as the wave weakens into a sound wave. The classic self-similar solution for a strong blast wave, the Sedov-Taylor solution, reveals a deep structural fact: in the strong-shock limit, the blast wave forgets everything about the explosion except its total energy. The details of the energy release — whether chemical, nuclear, or gravitational — are erased by the shock itself, producing a universal scaling law. This is emergence in its purest form: a specific, complex event is reduced by its own propagation to a single number, and everything else is thermal noise.