No teaching, no narrative. Just toys. Spawn a planet and watch its orbit; drop a hundred thousand balls through pegs and watch a bell curve form; click an object until it shatters. Play with the rules and see what happens next.
A smoothed-particle-hydrodynamics fluid you play with: pour water, stir it with the pointer, tilt gravity, and watch thousands of particles slosh, splash and settle with a real free surface.
Lay a truss of joints and beams across a gorge, then load it and watch every member stress green to red — and snap — as a rolling weight hunts for the weakest span.
Swing a heavy iron ball on a chain and watch a stacked brick wall topple, tumble and scatter under a real impulse-based rigid-body solver.
Air streams past a cylinder in a Lattice-Boltzmann fluid — raise the speed and watch the steady wake break into the oscillating von Kármán vortex street.
Tune a counterweight siege engine and fire — a falling weight whips a slung projectile down range to smash a castle wall, the whole linkage solved as a real multi-body system.
Pluck an elastic sheet of point masses and watch ripples race across the grid, reflect off pinned edges and interfere — a trampoline solved as a live network of damped springs.
Grab, poke and pile up squishy gas-pressure blobs — mass-spring shells that wobble, deform and bounce back to plump under a pressure-preserving solver.
Rack the balls, drag the cue to aim, and let elastic collisions, rolling friction and corner pockets play out a full break on green felt.
Rain thousands of balls through a triangular peg lattice and watch the central limit theorem build itself — a live histogram converging on the Gaussian, skewable left or right.
A playable side-view pinball table running honest 2D physics — launch the plunger, work two flippers, and ricochet off bumpers and slingshots that kick the ball back with real impulses.
A row of pendulums tuned by length swings into traveling waves, splinters into clusters and chaos, then snaps back into one wave as they rephase.
Launch a probe past moving planets and watch a gravity assist steal their momentum — a close pass behind a planet flings you faster, in front brakes you.
Lift the chrome spheres and let them clack — momentum and energy ripple through the touching line and fly out the far end.
Build a Rube-Goldberg contraption from ramps, pegs and bumpers, then unleash a glittering cascade of marbles that bounce, scatter and pour through everything you place.
Scatter bar magnets on the table and watch thousands of iron filings snap into the living lines of force — opposite poles linking, like poles fending each other off.
Buoyant blobs of molten wax heat at the base, swell and rise, cool and sink — merging and splitting as glowing metaballs.
Drop massive stars and watch thousands of test particles braid themselves into glowing orbital streams under softened Newtonian gravity.
Spin a driver and watch meshing gears, an epicyclic planet set, a rack-and-pinion and a crank-rocker linkage move in exact kinematic lockstep — ratios, torque and reciprocating motion made visible.
The classic powder toy: paint sand, water, oil, fire and living plant onto a cellular-automaton grid and watch them pile, flow, float, ignite and grow.
Drop + and − charges on the table and watch the electric field reconfigure live — field lines stitching dipoles together, like charges fending each other off, a capacitor pressing the field flat and uniform.
Two coherent waves interfere into bright and dark fringes — then fire quanta one at a time and watch the very same pattern rebuild itself, dot by dot.
Lay a chain of upright tiles along a curve, tip the first, and watch a toppling wave race down the line — or stall where the spacing grows too wide.
Pour sand grain by grain and watch a pile climb to its critical angle, then shrug off avalanches whose sizes trace a clean power-law — self-organized criticality made tactile.
Click any 3D object to shatter it into Voronoi fragments that fall under gravity. Press R to reform the pieces.
The Observatory as a 3D operating system — every section becomes a panel floating in a dark room you can drag, push into depth, and fly into. Navigation made spatial.
Click to spawn planets, drag to set velocity, and watch orbital mechanics unfold — resonances, ejections, captures. Share scenarios via URL.
Two simulations side-by-side: 100,000 balls forming a bell curve through a Galton pegboard, and 64 double pendulums diverging from near-identical starts.
Walk an infinite tunnel of physics-simulated cloth panels — scroll to fly forward, move the mouse to ripple the fabric.