> why shadows have fuzzy edges ? Shadows have fuzzy edges in geometric optics as well (unless you're mentioning usually micrometer-scale diffraction effects).

> why shadows have fuzzy edges ? Shadows have fuzzy edges in geometric optics as well (unless you're mentioning usually micrometer-scale diffraction effects). It's because illuminators are not point-like, so when viewed near an edge your light source progresses in size until it disappears (penumbra to umbra) https://en.wikipedia.org/wiki/Umbra,_penumbra_and_antumbra https://en.wikipedia.org/wiki/Umbra,_penumbra_and_antumbra