Supernova Expansion Estimator

The expansion of a supernova remnant follows the rigorous Sedov-Taylor scaling laws, driven by extreme thermodynamic disequilibrium. The shock front propagates spherically, characterized by R ∝ t^(2/5). This deterministic dissipation of energy through the interstellar medium represents a fundamental constraint on stellar evolution dynamics. Such macroscopic fluid behavior inevitably decelerates, adhering strictly to the conservation of mass, momentum, and energy across the interaction boundary.

At heart this tool uses the plainest formula in physics: distance equals speed times time, so the remnant's radius is R = vt. The clever part is the last step — the same shell looks tiny or huge depending on how far away it sits. Because angular size is roughly θ ≈ 2R/d, moving a remnant twice as far away halves the angle your telescope must resolve.

Run the Crab Nebula's motion backward at today's speeds and the filaments converge around the year 1130 — roughly 90 years after the supernova China recorded in 1054. The remnant is therefore accelerating, not coasting: the central pulsar's wind keeps pumping energy into the shell. So a constant-speed R = vt would date the explosion too late, a rare case where reality outruns the simple model.