Rho by Ciro Santilli 40 Updated 2025-07-16
This one is a little confusing: the upper case looks exactly like a letter P, but as the name suggests, it actually corresponds to the letter R. The letter P corresponds to pi instead.
Phi by Ciro Santilli 40 Updated 2025-07-16
Two lower case variants... both used in mathematical notation, and for some reason, in LaTeX \varphi is the one that actually looks like the default standard modern lowercase phi, while \phi is the weird one. I love life.
Psi (Greek) by Ciro Santilli 40 Updated 2025-07-16
As if it weren't enough, there's also a Cyrillic script psi that is slightly different. Life's great.
The BBC 1979-1982 adaptations of John Le Carré's novels are the best miniseries ever made:They are the most realistic depiction of spycraft ever made.
Some honorable mentions:
One of the most nerve wrecking movies ever made. Until they decide to rescue their colleague from jail, then it just becomes too surreal.
Gravity by Ciro Santilli 40 Updated 2025-07-16
In 2020 physics, best explained by general relativity.
TODO: does old Newtonian gravity give different force results than general relativity?
GPIO generally only supports discrete outputs.
But for some types of hardware, like LEDs and some motors, the system has some inertia, and if you switch on and off fast enough, you get a result similar to having an intermediate voltage.
So with pulse width modulation we can fake analog output from digital output in a good enough manner.
general linear group over a finite field of order . Remember that due to the classification of finite fields, there is one single field for each prime power .
Exactly as over the real numbers, you just put the finite field elements into a matrix, and then take the invertible ones.
Cocos2d by Ciro Santilli 40 Updated 2025-07-16
Ciro Santilli considered this as the basis for Ciro's 2D reinforcement learning games, but ultimately decided it was a bit too messy. Nice overall though.
Gallium arsenide by Ciro Santilli 40 Updated 2025-07-16
This is apparently the most important III-V semiconductor, it seems to actually have some applications, see also: gallium arsenide vs silicon.

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 5. . 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.
  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