Simulations you can push on

Our philosophy

Every simulation on this site is built to be touched, not watched. Drag a body, move a slider, flip a switch mid-run, and the system responds honestly — because nothing here is a pre-rendered video pretending to be interactive. If you've ever nudged a real pendulum to see what happens next, that's the instinct we're building for: understanding that comes from your own hands on the controls, not from a caption explaining what you should have concluded.

That only works if what's underneath is actually correct. The three bodies above aren't following a scripted path — they're being advanced step by step through Newton's law of gravitation, the same nine second-order equations that defeated a closed-form solution for over two centuries. Our 555 timer charges a capacitor through a real RC time constant. Our traveling-salesperson visualizer runs real 2-opt and simulated-annealing optimization, warts and false starts included. When a simulation looks like it's cheating to make a point look cleaner, we've failed — so we don't let it.

We also refuse to hide the math. It would be easy to smooth every rough edge into a friendly animation and never show a single equation, but the equation is usually the most interesting part — the reason the phenomenon behaves the way it does. So the governing law is right there next to the picture it produces:

None of this is abstract for its own sake. The equilateral solution that lets three unequal masses orbit forever without one drifting away is the same geometry that keeps roughly ten thousand Jupiter Trojan asteroids parked 60° ahead of and behind the planet — and it's the reasoning NASA used to place the James Webb Space Telescope in a halo orbit around a point in empty space where nothing pulls it there but the balance of the Sun's and Earth's gravity. Our 555 astable circuit is the exact timer chip inside decades of blinking LEDs, tone generators, and switching power supplies. The traveling-salesperson problem is what a delivery company and a chip router are both quietly solving, one heuristic at a time. Where the real-world application exists, we point to it — the goal isn't just "isn't this pretty," it's "this is why it matters."