Classical limit Updated 2025-07-16
The idea tha taking the limit of the non-classical theories for certain parameters (relativity and quantum mechanics) should lead to the classical theory.
It appears that classical limit is only very strict for relativity. For quantum mechanics it is much more hand-wavy thing. See also: Subtle is the Lord by Abraham Pais (1982) page 55.
Classical mechanics Updated 2025-07-16
Classification of 4-transitive groups Updated 2025-07-16
en.wikipedia.org/w/index.php?title=Mathieu_group&oldid=1034060469#Multiply_transitive_groups is a nice characterization of 4 of the Mathieu groups.
Classification of finite fields Updated 2025-07-16
There's exactly one field per prime power, so all we need to specify a field is give its order, notated e.g. as .
It is interesting to compare this result philosophically with the classification of finite groups: fields are more constrained as they have to have two operations, and this leads to a much simpler classification!
Classification of finite groups Updated 2025-07-16
As shown in Video "Simple Groups - Abstract Algebra by Socratica (2018)", this can be split up into two steps:This split is sometimes called the "Jordan-Hölder program" in reference to the authors of the jordan-Holder Theorem.
Good lists to start playing with:
History: math.stackexchange.com/questions/1587387/historical-notes-on-the-jordan-h%C3%B6lder-program
It is generally believed that no such classification is possible in general beyond the simple groups.
Classification of regular polytopes Updated 2025-07-16
The 3D regular convex polyhedrons are super famous, have the name: Platonic solid, and have been known since antiquity. In particular, there are only 5 of them.
The counts per dimension are:
The cool thing is that the 3 that exist in 5+ dimensions are all of one of the three families:Then, the 2 3D missing ones have 4D analogues and the sixth one in 4D does not have a 3D analogue: the 24-cell. Yes, this is the kind of irregular stuff Ciro Santilli lives for.
Climate of the United Kingdom Updated 2025-07-16
Closed standard Updated 2025-07-16
How the hell are you supposed to develop an open source implementation of something that has a closed standard?
Closurism Updated 2025-07-16
Closurism is a term invented by Ciro Santilli to refer to content moderation policies that lock threads in online forums, preventing people from adding new comments from that point onward.
This is similar to deletionism but a bit less worse, as the pre-existing content is maintained. But new relevant content that comes up cannot be added in the future, so it is still bad.
The outcome of closurism is that new forum posts must then be made about up-to-date aspects of the topic. But then those may fail to reach the same PageRank, so most people never get the new information, or create new posts leading to useless duplication of work.
Cody'sLab Updated 2025-07-16
This dude is mind blowing. Big respect.
Some of the most impressive videos are the ones in which he goes and extracts metals from minerals himself all the way.
Shame the academic system wasn't compatible with him: www.reddit.com/r/codyslab/comments/f5531p/codys_qualifications/ Maybe there were safety issues involved though.
ColdQuanta Updated 2025-07-16
Not a quantum computing pure-play, they also do sensing.
Collatz conjecture Updated 2025-07-16
Given stuff like arxiv.org/pdf/2107.12475.pdf on Erdős' conjecture on powers of 2, it feels like this one will be somewhere close to computer science/Halting problem issues than number theory. Who knows. This is suggested e.g. at The Busy Beaver Competition: a historical survey by Pascal Michel.
Comma-separated values Updated 2025-07-16
CommonMark Updated 2025-07-16
CommonMark is a good project. But its initial release method was not very nice, they first developed everything behind closed doors with the big adopters like GitHub and Stack Overflow, and only later released the thing read, thus wasting the time of people who were working on alternative in the meanwhile, e.g. github.com/karlcow/markdown-testsuite which Ciro contributed to: Ciro Santilli's minor projects.
Commutative property Updated 2025-07-16
Company with a semiconductor fabrication plant Updated 2025-07-16
A list of fabs can be seen at: en.wikipedia.org/wiki/List_of_semiconductor_fabrication_plants and basically summarizes all the companies that have fabs.
Computable function Updated 2025-07-16
History of polarization Updated 2025-07-16
Good overgrown section in the middle of Fresnel's biography: en.wikipedia.org/w/index.php?title=Augustin-Jean_Fresnel&oldid=1064236740#Historical_context:_From_Newton_to_Biot.
Particularly cool is to see how Fresnel fully understood that light is somehow polarized, even though he did not know that it was made out of electromagnetism, clear indication of which only came with the Faraday effect in 1845.
spie.org/publications/fg05_p03_maluss_law:
At the beginning of the nineteenth century the only known way to generate polarized light was with a calcite crystal. In 1808, using a calcite crystal, Malus discovered that natural incident light became polarized when it was reflected by a glass surface, and that the light reflected close to an angle of incidence of 57° could be extinguished when viewed through the crystal. He then proposed that natural light consisted of the s- and p-polarizations, which were perpendicular to each other.
Computer chess interface Updated 2025-07-16
Computer music Updated 2025-07-16
Unlisted articles are being shown, click here to show only listed articles.