# How can shadows ever be sharp?

When I hold my hand underneath my lamp, the shadow my hand casts is crisp and sharp, meaning that the edges are well defined and not blurred. But according to Huygen's principle, shouldn't the light diffract upon reaching the edges of my hands, and perhaps form interference patterns? If so, how can the shadow my hand cast ever be crisp?

• The short answer (ignoring Huygens principle and thinking of light like waves on a pond) is that frequencies of $10^4$ Hz end up being a totally different ball game than frequencies of $10^{14}$ Hz.
– user12029
Mar 13, 2015 at 23:59