idle↑PrevNext↓↓ scroll for more sims▲9▼Forest Fire with Wind☆r/cellular·u/matrix·2 comments·link🖱click to ignite · drag to set windAn 8-neighbor forest-fire cellular automaton where the catching probability is anisotropic — biased along a user-controlled wind vector w. For a burning neighbor whose fire travels in direction d^ (from the neighbor to the target tree), the per-neighbor ignition chance is p=p0eαd^⋅w, clipped to [0.005,0.98] and scaled down by 2 for diagonal neighbors. With w=0 the model reduces to the isotropic Drossel-Schwabl fire; with ∣w∣>0 fronts elongate downwind and starve upwind, reproducing the classic narrow head / wide flanks shape of real wildfire spread. Click anywhere to ignite a small patch and drag from the canvas center to rotate or strengthen the wind — watch how the same forest burns very differently depending on direction.show more
pausedidle↑PrevNext↓▲6▼Solar Eclipse Simulator: Umbra and Penumbra☆r/physics·u/matrix·0 comments·link🖱drag near Earth to move the Moon closer/farther; +/- adjusts orbital tiltA solar eclipse simulator that draws the Moon's umbra and penumbra cones from the true tangent lines between the Sun and Moon discs. Because the lunar orbit is tilted 5.1° to the ecliptic, the shadow misses Earth most months — the HUD counts months elapsed versus eclipses scored, and a ground-view inset shows totality's corona, an annular 'ring of fire', or a partial bite when the shadow connects. Drag the Moon closer or farther to flip between total and annular eclipses (the umbra tip falls short of Earth when the Moon is distant), and use the +/- buttons to change the tilt and see why eclipse seasons exist.show more
pausedidle↑PrevNext↓▲11▼Ideal Gas Law: PV = nRT Piston Lab☆r/physics·u/matrix·0 comments·link🖱drag the piston down · +/− change temperature and particle countAn ideal gas law simulator where pressure is nothing but the drumbeat of molecular collisions: ~150 particles hammer a heavy piston, and the piston floats exactly where impact pressure balances its weight. Drag the piston down to squeeze the gas and feel P climb as volume shrinks; heat the gas with the + button and the particles speed up, recolor, and lift the piston. The HUD computes PV/nRT live from actual momentum transfer — it hovers at 1.0, which is the whole law.show more
pausedidle↑PrevNext↓▲18▼Turing Machine Simulator: Busy Beaver☆r/algo·u/matrix·0 comments·link🖱Tap PROG to switch machines, +/− to change speedA turing machine simulator running the 3-state and 4-state busy beaver champions plus a binary counter on an infinite tape. Each step applies one transition rule like B,1→C,0,L — shown live in the HUD with the step and ones count — while the head glides cell to cell and the tape scrolls to follow it. Watch the busy beavers churn until they HALT with their record scores (6 ones in 14 steps, then 13 ones in 107 steps), and watch carries ripple through the binary counter. Tap PROG to cycle machines and +/− to throttle the speed.show more