# \#unilluminable-room

**URL:** https://scanalyst.fourmilab.ch/tag/unilluminable-room/1948.md

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## [Building an Unilluminable Room](https://scanalyst.fourmilab.ch/t/building-an-unilluminable-room/1370)

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**Author:** [@johnwalker](https://scanalyst.fourmilab.ch/u/johnwalker)\
**Replies:** 0\
**Last updated:** [15 May 2022 12:33 UTC](https://scanalyst.fourmilab.ch/t/building-an-unilluminable-room/1370 "2022-05-15T12:33:01Z")

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Is it possible to design a room entirely lined with mirrors which cannot be completely illuminated by a point light source placed at any position? This is the “illumination problem”, posed by Ernst Straus …