The 26-Sided Unilluminable Room

​
number of reflections
6
starting direction
starting direction π/4 ×
0
1
2
3
4
5
6
7
rays per beam
24
beam opening angle
color
by reflection
by ray
uniform
uniform ray style
thickness
opacity
show initial direction
show red dots
If a candle is inside a room with mirrored walls, can any portion of the room be dark? In 1958, a young Roger Penrose found an unilluminable room with elliptical sides. In 1995, George Tokarsky proved that a light ray starting from one corner of a mirrored 45 degree triangle could never return to that corner. From that, he built a 26-sided room such that a single point of light would lead to a single point of darkness elsewhere in the room. The red dots are a pair of points that theoretically cannot illuminate each other.

External Links

Illumination Problem (Wolfram MathWorld)

Permanent Citation

Michael Trott
​
​"The 26-Sided Unilluminable Room"​
​http://demonstrations.wolfram.com/The26SidedUnilluminableRoom/​
​Wolfram Demonstrations Project​
​Published: September 17, 2007