Magnetohydrodynamics. Two dimensions. Zero shortcuts.
A 128×128 ideal-MHD solver running live on the Mac Mini. Orszag-Tang initial conditions on a 2π periodic domain. Mass, energy, and ∇·B all conserved to machine precision. Every step feeds the public entropy beacon.
Lax-Friedrichs · Δm/m < 10-15 · ∇·B < 10-15
Ideal MHD in conservation form. 6 field components per cell (ρ, vx, vy, p, Bx, By). Lax-Friedrichs fluxes on a 128² periodic grid. First-order in space — diffusive at shocks, exact where it counts.
The canonical 2D MHD test. Smooth initial conditions evolve into turbulent small-scale structure with sharp shock fronts. Our solver conserves mass and energy to machine precision (Δm/m < 10-15, ΔE/E < 10-15) and maintains ∇·B at 10-15 by construction. Lax-Friedrichs on a 1282 periodic grid — diffusive at shocks, exact where it counts.
Live density field (ρ) sampled from /entropy/frame/current — the 128×128
solver grid on a 2π periodic domain, min-max normalized and color-mapped in your GPU. A new
attested frame lands ~every 2 s — one per beacon pulse — and the display
cross-dissolves between them for smooth motion. Every keyframe has been hashed and signed into the
entropy chain.
Plasma is chaotic. Small perturbations blow up fast. That makes it a good random-source — the output of a correctly-running MHD step is unpredictable even to us, which is the property we need for an honest entropy beacon. And it's beautiful to look at.
There's a serious version of this argument involving fusion reactor control, but we'll let the beacon make the case.