The Impossible Mini-Golf Hole
A ball hit at point A, in any direction at any speed, will never enter the hole at point B. The ball, of any elasticity, could bounce forever - but it would never reach its destination.
A similar idea was presented by Ernst Straus in the 1950s - would a room lined with mirrors always be completely illuminated by a single light? Finally, in 1997, D. Castro presented the figure above. He proposed that if a candle is placed at point A in a room full of mirrors, and you stand at point B - you will never see the reflection of the candle. Light, much like the hypothetical golf ball, only travels in straight lines - and no straight path can ever start at Point A and eventually end at Point B. Although this seems counterintuitive, trust the math.
