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
![](https://i0.wp.com/chalkdustmagazine.com/wp-content/uploads/2017/03/AntigoniK.png?resize=150%2C150)
Antigoni is a PhD student at UCL working on Boundary Element Methods for electromagnetic scattering.
More from Chalkdust
Chalkdust issue 17 – Coming 22 May
Pre-order a copy and/or book your ticket for our launch eventWhat’s hot and what’s not, issue 08
Fashion is fleeting, Chalkdust regulars are not.Chalkdust Issue 06 coming 19 October
Free launch party, 7.15pm. Come along!Creating hot ice
We created hot ice from scratch, a solution that remains liquid even below its freezing point!Curiouser and curiouser!
Some surprising mathematical factsFind your perfect partner
Find your perfect partner with this wonderful tree diagram!