The collection grew out of a single page on the cuprate problem, written to see whether the open questions of a subfield could be set out precisely enough for someone from a different corner of physics to work on them. It now runs to sixteen chapters, from quantum gravity and black holes through the early universe and neutrinos to turbulence, strange metals and the structure of local quantum field theory.
Eighty questions carry stable identifiers, so that one of them can be cited and returned to later. Each chapter says what is established, what is conjectured and where the disagreement actually sits, with the literature attached to the people who did the work. A method guide explains how the questions were chosen and what makes one of them attackable, a glossary carries the terms a reader from another subfield will not have, and the sources page states the scope limits together with the date the literature was checked.
The question notebook lets a reader mark a question as read or in progress and keep notes beside it. Those notes stay in the browser and are never sent anywhere; the Export notebook button writes them to a file, for keeping or for moving to another machine. The pages work offline, including the equation renderer. The external links to arXiv and to the official problem statements need a connection.
A word on what this is: a pedagogical collection, assembled to make a subfield approachable. It does not attempt a systematic review, and a question listed here is not thereby certified as open. The four figures use stated mathematical models; none of them shows experimental data. The cuprate page the collection grew from is kept unchanged as reference material, and its thirty-two questions are counted separately from the eighty.