Placeholder body. The editorial content of this post has not been written yet — only its frontmatter is real, migrated from the entry that previously lived in src/data/journal.ts.

A wave arrives, strikes something, and leaves. What reaches the sensor is not the object but the disturbance it caused. Reconstruction is the work of going backwards: inferring shape and position from the ripples alone.

It is easier to see than to describe. Drag either target below and watch the scattered pattern rearrange:

Plane wave scattering from two draggable targets

The forward direction is physics. The backward direction — the one that matters for sensing — is Spatial reconstruction.