How to use it
Drag Position spread Δx. The top curve (where the particle is) narrows, and the bottom curve (its momentum) widens, automatically. The meter shows the product Δx·Δp, which can never drop below ℏ/2. Switch the state to see shapes that sit above the floor.
What you're actually seeing
Two views of one quantum state. Top: |ψ(x)|², the probability of position. Bottom: |φ(p)|², the probability of momentum: the Fourier transform of the top. They are the same object in two languages; you cannot make both narrow at once.
It's not about disturbance
The popular story, "measuring kicks the particle", is Heisenberg's 1927 heuristic, not the principle. The real statement (Kennard 1927) is about preparation: no wave can have both a sharp position and a sharp momentum, because narrow-in-x means broad-in-p. It's a theorem about Fourier transforms, true before anyone looks.
What's exact, what's stylised
Exact: the bound Δx·Δp ≥ ℏ/2, the Gaussian saturating it, the Fourier relationship, and the real electron numbers. Stylised: the carrier-wave animation and scaled display units; Δx is read as nanometres for the real-scale figure.