Musical study Updated 2025-07-16
Modulo operation Updated 2025-07-16
Modular multiplication Updated 2025-07-16
Modular exponentiation Updated 2025-10-14
Can be calculated efficiently with the Extended Euclidean algorithm.
The beauty of this algorithm is that because exponentiation grows really fast, there is no hope that we can ever learn all the digits of an exponential, as there is simply not enough time or memory for that. Therefore, a natural sub-question is if we can know some part of that number, and knowing the smallest digits is the most natural version of that question.
Leeuwenhoek microscope Updated 2026-08-21
Phase-contrast microscopy Updated 2025-07-16
Electron microscope Updated 2025-07-16
All of them need a vacuum because you can't shoot elecrons through air, as mentioned at Video "50,000,000x Magnification by AlphaPhoenix (2022)".
Two-photon excitation microscopy Updated 2025-07-16
Two Photon Microscopy by Nemonic NeuroNex (2019)
Source. Shows a prototype of a two-photon electron microscope on an optical table, and describes it in good detail, well done. X-ray crystallography Updated 2025-07-16
One of its main applications is to determine the 3D structure of proteins.
Sometimes you are not able to crystallize the proteins however, and the method cannot be used.
Crystallizing is not simple because:
Cryogenic electron microscopy can sometimes determine the structures of proteins that failed crystallization.
Microscopy bibliography Updated 2025-07-16
- micro.magnet.fsu.edu/index.html OLD website with great design and much love. Some notable things:
Break the meta Updated 2025-07-16
To break the meta means to find a new strategy that offers a significant advantage over the existing meta.
Due to Ciro Santilli's self perceived creative personality, Ciro Santilli is very attracted to meta breaks.
How One Man Changed the High Jump Forever by Olympics (2018)
Source. Dick Fosbury created and implemented the Fosbury Flop jump style in 1968. One page to rule them all Updated 2025-07-16
It is true that one image is worth a thousand words, but unfortunately it is also true that one image takes up at least as much bytes as a thousand words!
Having one single page to rule them all is of course the ideal setup for a website, as you can Ctrl + F one ToC and quickly find what you want.
And, with Linux Kernel Module Cheat Ciro noticed that it is very hard to write so much intelligent prose that becomes larger than reasonable to load on a single webpage.
He then started using this technique for everything he writes, including this page and Chinese government.
However, if there are too many images on the page, the loading of the last images would take forever in case users want to view the last sections.
There are two solutions to that:
- be traditional and create separate web pages
- be bold and load images as they appear on the viewport: stackoverflow.com/questions/2321907/how-do-you-make-images-load-only-when-they-are-in-the-viewport/57389607#57389607Edit: OK, it was standardized with
loading=lazy, without need JavaScript!Now the last awesome thing would be a method that loads first images in viewport, then those below, and then those above, that would be the ultimate solution.This question comes close: stackoverflow.com/questions/7906348/change-loading-order-of-images-already-on-page
Ciro is still deciding between those two. The traditional approach works for sure but loses the one page to rule them all benefits.
The innovative approach will work for interactive viewing, but archive.org will fail to load the images for example, and there may be other unforseen consequences.
Wikimedia Commons is awesome and automatically converts and serves smaller versions of images, so always choose the smallest images size needed by the output document. Readers can then find the higher resolution versions by following the page source.
This also comes to mind: motherfuckingwebsite.com
zettelkasten.de/posts/overview/ from zettelkasten:
How many Zettelkästen should I have? The answer is, most likely, only one for the duration of your life. But there are exceptions to this rule.
Where to store images Updated 2025-07-16
Since images are large, they bring the following challenges:
To solve those problems, the following alternatives appear to be stable enough and should be used decreasing preference:
- This way, the entire website is relies on a single third party: GitHub, so we have a simple single point of failure.We are at the mercy of GitHub's 1GB size policy: help.github.com/en/articles/what-is-my-disk-quota, but it will take a while to hit that.GitLab however has a 10Gb maximum size: about.gitlab.com/2015/04/08/gitlab-dot-com-storage-limit-raised-to-10gb-per-repo/ so we could move there is we ever blow up 1Gb on GitHub.
- Wikimedia Commons for videos if the following conditions are met:
- in scope: "educational material in a broad sense", but not e.g. "Private image collections, e.g. private party photos, photos of yourself and your friends, your collection of holiday snaps and so on.". I don't think they will be too picky even with low quality photos.
- allowed format, e.g. images or videos, but not ZIPs
- allowed license: CC BY SA, but no fair use
Since Wikimedia Commons has a higher level of curation and is an educational not-for-profit, it is the method most likely to remain available for the longest time.For this reason, we highly recommend uploading any acceptable files there as well as an additional backup.The downside is that its tooling is not as good, e.g. there are a bunch of messy unofficial tools for batch operations, and upload takes more effort.Another downside of Wikimedia Commons is that while we can choose the basename of files, it also adds some extra SHA crap to the beginning of URLs, making them harder to predict.Another serious downside is that they randomly rename images without redirects... e.g. they renamed upload.wikimedia.org/wikipedia/en/0/03/STJ_SVG_file.svg to upload.wikimedia.org/wikipedia/commons/8/81/Superconducting_tunnel_junction.svgAnother "downside" is that they are extremely strict about copyright compliance. This is good because you can be pretty sure that they are correct in general, but it also means that they are very conservative, and delete things where fair use would be OK. And if those fair uses have no Wikipedia page, they won't show up anywhere. - All content will be tracked under the
cirosantillicollection: archive.org/details/cirosantilliarchive.org has a very convenient upload and lax requirements. The generated URLs are predictable (single SHA prefix for the entire collection).Never trust a website that is not on GitHub Pages, for-profit companies will take down everything immediately as soon as it stops making them money.Every external link to non-GitHub pages must be archived. And GitHub links must be forked.We should also backup images that Wikimedia Commons does not accept here in addition to the github.com/cirosantilli/media repository.
The following alternatives seem impossible because Ciro could not find if they expose direct links to the images:
The following do have direct links:
- www.flickr.com e.g. live.staticflickr.com/7437/27402357162_7d91b73cd5_z.jpg documented at help.flickr.com/en_us/get-the-url-of-a-flickr-photo-S1Hnnmjym Also does automatic image size conversion. But only provides ugly autogenerated URLs.
- Instagram does not support upload from computer? Lol?
Mechanical engineering company Updated 2025-07-16
3Blue1Brown Updated 2025-07-16
Python graphics engine open sourced at: github.com/3b1b/manim "Animation engine for explanatory math videos". But for some reason there is a community fork: github.com/ManimCommunity/manim/ "This repository is maintained by the Manim Community, and is not associated with Grant Sanderson or 3Blue1Brown in any way (though we are definitely indebted to him for providing his work to the world). If you want to study how Grant makes his videos, head over to his repository (3b1b/manim). This is a more frequently updated repository than that one, and is recommended if you want to use Manim for your own projects." what a mess.
MathDoctorBob Updated 2025-07-16
He got so old from 2012 to 2021 :-)
This dude did well. If only he had written a hyperlinked wiki rather than making videos! It would allow people to jump in at any point and just click back. It would be Godlike.
mathdoctorbob.org/About.html says:
Robert Donley received his doctorate in Mathematics from Stony Brook University and has over two decades of teaching experience at the high school, undergraduate, and graduate levels.
Theorem of the Day Updated 2025-07-16
Capoeira Updated 2025-07-16
Dojo Updated 2025-07-16
Propositional logic Updated 2025-07-16
In some systems, e.g. including Metamath, modus ponens alone tends to be enough, everything else can be defined based on it.
There are unlisted articles, also show them or only show them.
