Suppose a light source is placed in a polygonal hall of mirrors (so light can bounce off the walls). Does every point in the room get illuminated? This elementary geometrical question was open from the 1950s until Tokarsky (1995) found … Continue reading Colloquium: Tuesday March 24, 2pm. Speaker: Barak Weiss (Tel Aviv). Title: Everything is Illuminated (Except for at Most Finitely Many Points)