Piano by Ciro Santilli 40 Updated 2025-07-16
The piano is the most elegant non-electronic instrument. But it requires way too many strings, so expensive and not portable.
Also it allows for no legato or vibrato.
The guitar is kind of the opposite.
After computer sound synthesis however, all of these distinctions become meaningless.
Nature Scitable by Ciro Santilli 40 Updated 2025-07-16
As of 2022 visible at: www.nature.com/scitable
Apparently they had a separate URL as just scitable.com, so they were somewhat serious about it before shutting it down.
As of 2022 marked:
This page has been archived and is no longer updated
RIP.
www.nature.com/scitable/blog/student-voices/ has last entry 2015, so presumably that's the shutdown year.
Self description:
Using our platform, you can customize your own eBooks for your students. Create an online classroom. Contribute and share content and connect with networks of colleagues.
so quite related to OurBigBook.com.
Wikipedia dumps by Ciro Santilli 40 Updated 2025-07-16
Per-table dumps created with mysqldump and listed at: dumps.wikimedia.org/. Most notably, for the English Wikipedia: dumps.wikimedia.org/enwiki/latest/
The tables are "documented" under: www.mediawiki.org/wiki/Manual:Database_layout, e.g. the central "page" table: www.mediawiki.org/wiki/Manual:Page_table. But in many cases it is impossible to deduce what fields are from those docs.
MOOCs are a bad idea. We don't want to simply map the pre-computer classroom to the Internet. The Internet allows, and requires, fundamentally new ways to do things. More like Stack Overflow/Wikipedia. More like OurBigBook.com.
After Ciro Santilli got a lot of attention on Hacker News news.ycombinator.com/item?id=19428700 his Stack Overflow account was suspended for 3 days web.archive.org/web/20190320163458/https://stackoverflow.com/users/895245/ciro-santilli-新疆改造中心-六四事件-法轮功 and he received a magic notification that led to a private message:
Hello,
I'm writing in reference to your Stack Overflow account:
I don't understand why you are actively promoting and assisting people to commit fraud on the site.
I've removed this from your profile github.com/cirosantilli/stack-overflow-vote-fraud-script and do not expect you to post it around the site.
I'm suspending you to gain your attention on this matter.
We have temporarily suspended your account; you may return after 3 days.
Regards,
To: Aaron Hall ♦;Andy ♦;Baum mit Augen ♦;Bhargav Rao ♦;Bohemian ♦;BoltClock ♦;Brad Larson ♦;ChrisF ♦;Cody Gray ♦;deceze ♦;Ed Cottrell ♦;Flexo ♦;George Stocker ♦;Jean-François Fabre ♦;Jon Clements ♦;josliber ♦;Madara Uchiha ♦;Martijn Pieters ♦;meagar ♦;Michael Myers ♦;Rob ♦;Robert Harvey ♦;Ry- ♦;Samuel Liew ♦;Undo ♦;Yvette Colomb ♦
Ciro's reply was:
Hi mods,
Reply and unsuspend quickly followed, with link still removed:
I suspended you to get your attention. Your attitude about going to Twitter about it does not bode well with me.
Feel free to have whatever you want in your GitHub repo. Just don't advertise tools to make it easier for people to circumvent the rules. As easy or as hard as it may be to circumvent them, you're handing it to people who may not be capable of doing so. It doesn't help.
Don't make threats to upload on an anonymous account. Accounts created to circumvent previous warnings are not welcomed on the site.
We don't need a meta thread to discuss whether it's ok to post voting fraud links in your profile and we definitely don't need to give it anymore publicity.
I'll unsuspend you, now we've had this discussion.
Regards,
A meta thread was later created by Yvette, kudos, to which Ciro answered with the correct unpopular answer that will be downvoted to oblivion: meta.stackoverflow.com/questions/381577/is-it-ok-to-have-links-on-how-to-create-sock-puppets-and-gain-rep-fraudulently-i/381635#381635
Yvette had also previously deleted one or two of Ciro's answers for being duplicates, which is a policy Ciro is against: if the questions are not dupes, a single answer might still directly reply to both of them.
Yvette later announced that she was leaving the website: meta.stackoverflow.com/questions/399495/leaving-the-site-and-the-network-mid-election-is-not-the-best-but-theres-no. This is evil, but Ciro was happy. He does not mean harm to Yvette, but in their limited interaction, Ciro disagreed with her choices.
Video 1.
The Great Places Erased by Suburbia by Not Just Bikes (2022)
Source. Stack Overflow, and other online forums, can serve as a sort of a third place for its more active users.
There's no point.
The question remains there, but people lose the ability to help the asker.
Reputation is meaningless regardless, since JavaScript gurus will always have 1000x more readers than low level junkies.
The deeper problem: the existence of multiple separate websites instead of just using the tags on a single website.
Cycler Turing machine by Ciro Santilli 40 Updated 2025-07-16
These are very simple, they just check for exact state repetitions, which obviously imply that they will run forever.
Unfortunately, cyclers may need to run through an initial setup phase before reaching the initial cycle point, which is not very elegant.
Also, we have no way of knowing the initial setup length of the actual cycle length, so we just need an arbitrary cutoff value.
And unfortunately, this can lead to misses, e.g. Skelet machine #1, a 5 state machine, has a (translated) cycle that starts at around 50-200M steps, and takes 8 trillion steps to repeat.
Uncertainty principle by Ciro Santilli 40 Updated 2025-07-16
The wave equation contains the entire state of a particle.
And a single vector can be represented in many different ways in different basis, and two of those ways happen to be the position and the momentum representations.
More importantly, position and momentum are first and foremost operators associated with observables: the position operator and the momentum operator. And both of their eigenvalue sets form a basis of the Hilbert space according to the spectral theorem.
When you represent a wave equation as a function, you have to say what the variable of the function means. And depending on weather you say "it means position" or "it means momentum", the position and momentum operators will be written differently.
Furthermore, the position and momentum representations are equivalent: one is the Fourier transform of the other: position and momentum space. Remember that notably we can always take the Fourier transform of a function in due to Carleson's theorem.
In precise terms, the uncertainty principle talks about the standard deviation of two measures.
We can visualize the uncertainty principle more intuitively by thinking of a wave function that is a real flat top bump function with a flat top in 1D. We can then change the width of the support, but when we do that, the top goes higher to keep probability equal to 1. The momentum is 0 everywhere, except in the edges of the support. Then:
This is mostly stuff from before 2016 when Ciro was anxious to document his contributions to get a job.
Most of the projects here are also minor contributions, or Ciro later noticed that the projects were not useful enough to work on and that he was actually wasting his time.

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