As we build up light rays, the shape of the envelope begins to emerge. The only difference between this diagram and the physical system is that here, the overlap makes a dark envelope, whereas in the cup the overlap makes a bright envelope
More from Chalkdust
Don’t connect four
David Budd gets carried away joining the dots. Resistance is few-tile.
Dear Dirichlet, Issue 18
Phone assistants, duplicating pastries, and being a 10 anywhere else are among the topics of discussion in this issue's Dear Dirichlet advice column
Creating hot ice
We created hot ice from scratch, a solution that remains liquid even below its freezing point!
Review of Elastic Numbers
We have a go at the puzzles in Daniel Griller's new book
Curiouser and curiouser!
Some surprising mathematical facts
Find your perfect partner
Find your perfect partner with this wonderful tree diagram!