ψ · 3D first · front-end only · no sign-up · works offline
Quantum Ladder
This is not an e-book. 12 interactive 3D scenes do the teaching here: every important principle is pushed as far as three dimensions can take it, so that you *see* what is happening before anyone shows you a formula. Every calculation runs live in your browser.
Start with these five
All modules →Bloch sphere
A spin state you can drag around a sphere
Every point on the sphere is a pure state. Add a field and watch it precess, pick an axis and watch it collapse, repeat two hundred times and watch the frequencies converge on the Born rule.
Hydrogen orbitals
Actually see what |ψ|² looks like
Sixty thousand dots develop one by one, each a possible outcome of a position measurement. Change n, l, m, and slice a 3d orbital open to see inside.
Wells and the oscillator
Why a stationary state is called "stationary"
ψ spins endlessly in the complex plane while its shadow |ψ|² does not move at all. Levels, nodes and the exponential tail leaking through the wall are all in one picture.
Double-slit interference
The fringes are built one particle at a time
The first few dozen dots look random; after a few hundred the fringes surface by themselves. Put a detector at the slits and they vanish on the spot.
Tunnelling
A wave packet hits a wall it cannot climb
The time-dependent Schrödinger equation, solved live in your browser. The classical ball bounces straight back; part of the wave packet turns up on the far side.
3D does the teaching
Anything three dimensions can explain never gets reduced to a flat figure or a paragraph. Every scene rotates, zooms, clips, evolves in time and offers preset viewpoints.
The numbers are computed
Eigenvalue problems, split-operator evolution and Monte Carlo sampling all run in the browser. The readout puts the numerical and analytic answers side by side so you can check them.
Picture first, mathematics second
Every scene comes with a guide to what to look at and what to change, plus a set of common wrong intuitions — the traps almost everybody falls into once.
Three routes, depending on where you are coming from
First encounter with quantum mechanics
Take the modules in order: 01 → 02 → 03 → 04. Four modules in, you will already spot most of what popular accounts get wrong.
Currently taking a course
Whatever the lecture covers, come and look at the matching picture, then go back to the derivation. Each scene links straight to the relevant textbook section.
There is a whole textbook as well
The 3D modules build the picture; the derivations, exercises and numerical methods live in the textbook: 18 chapters, 106 sections, 106 of them finalised. Every module page links straight to the matching chapters.
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Your progress stays in this browser
12
3D scenes
16
modules
106
textbook sections