One reasonable and memorable approximation excluding any fine structure is:
Equation 1.
Hydrogen spectral series mnemonic
.
see for example example: hydrogen 1-2 spectral line.
Examples under python.
Ciro Santilli's wife was studying a bit of basic Python for some job interviews, when she noticed:
Wow, in is so powerful! You can do for x in list, for x in dict and if x in dict all with that single word!
Damn right, girl, damn right.
Ciro remembers hearing about Python online briefly. It seemed like a distant thing from the Java/C dominated (and outdated) university courses. Then some teaching assistant mentioned during some course when Ciro was at École Polytechnique that Python was a great integration tool. That sounded cool.
Then finally, when the École Polytechnique mathematics department didn't let Ciro Santilli do his internship of choice due to grades and Ciro was at an useless last moment backup internship, he learned more Python instead of doing his internship job, and was hooked.
From Scientific Autobiography by Max Planck translated by Frank Gaynor (1949):
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
Figure 1.
How Math works by SMBC Comics
. Source. An amazing representation of Science makes progress funeral by funeral. Steps:
  • Step 1: Insight
  • Step 2: Resistance
  • Step 3: Debate
  • Step 4: Additional decades of debate
  • Step 5: Changing of the guard
  • Step 6: Transmission to students
Ciro Santilli often sees all those genius who are much smarter than him making shitty forum/mailing list posts, they need to learn this:
  • The apparently most important one liner error message must appear in the title, and fuller apparently relevant logs must appear on the body
  • You must always give the version of the software that you are using as either a tag or git SHA
    These are an important part of the minimal working example.
  • For build errors, you must give your OS and compiler version and version of any relevant external library
Kaon by Ciro Santilli 40 Updated 2025-07-16
One strange quark bound with one up quark or a down quark. 6 combinations exist, 4 if we consider antiparticles the same as particles.
Hash function by Ciro Santilli 40 Updated 2025-07-16
Applications:

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact