In this book, ” by Indu Satija, with contributions by Douglas Hofstadter, is the first book ever to tell the story of the “Hofstadter butterfly”, a beautiful and fascinating graph lying at the heart of the quantum theory of matter. The butterfly came out of a simple-sounding question: What happens if you immerse a crystal in a magnetic field? What energies can the electrons take on? “
Ah ha!! It’s the “Farey organization of periodic regimes” that I was looking for in my numerator/denominator search the other day.
Thank you Indubala I Satija for writing “Butterfly in the Quantum World” and your publisher IOPscience for making the “free chapter” precisely the one that had the name of the thing I was looking for.
Free to read
The fractal family