Uncoiling the spiral: Maths and hallucinations (plus.maths.org)

Fascinating stuff. I've often thought that the nature of hallucinations - geometric or otherwise - must have lots to tell us about the workings of the brain. From a mechanistic viewpoint all our experiences (hallucinations included) supervene on brain structure, therefore these common geometric hallucinations likely reflect some fundamental structure of the brain.

On a related note, here's an interesting article from 2015 about encrypting information so that only people who are on LSD can read it: https://qualiacomputing.com/2015/05/22/how-to-secretly-commu...

Probably deserves a "2009" in the title. The 2015 HN discussion had only one comment, but that comment had an interesting link.

https://news.ycombinator.com/item?id=10397619