Aperiodic monotile Updated 2025-07-16
Aperiodic tiling Updated 2025-07-16
Doing physics means calculating a number Updated 2025-07-16
It does not matter how, if it is exact, or numerical, or a message from God: a number has to come out of the formulas in the end, and you have to compare it with the experimental data.
Many theoretical physicists seem to forget this in their lectures, see also: Section "How to teach and learn physics".
How Ciro Santilli manages to write so much Updated 2025-07-16
- Suck at your job:
- Have bad memory so you have to take notes: Ciro Santilli's bad old event memory
- Be a compulsive knowledge hoarder: Ciro Santilli's knowledge hoarding
- Seek glory over money: Ciro Santilli's selfish desires
- Try to make a carrier out of it: OurBigBook.com
- Be born compassionate: Ciro Santilli's self perceived compassionate personality
- He doesn't actually write that much, but when he does he focuses on higher impact stuff, see remarks about "He doesn't like to refresh the homepage looking for easy reputation" on Section "Ciro Santilli's Stack Overflow contributions"
- Contribute in a place where it is super easy for people to give you upvotes if they like your stuff. This way, you will see the uploads, and that will motivate you to re-read your content and make it more perfect with additions and corrections.
Personal knowledge instance Updated 2025-07-16
Sitare Foundation Updated 2025-07-16
Special linear group of dimension 2 Updated 2025-07-16
University spin-off company Updated 2025-07-16
Aberration (astronomy) Updated 2025-07-16
Busy beaver Updated 2025-07-16
The busy beaver game consists in finding, for a given , the turing machine with states that writes the largest possible number of 1's on a tape initially filled with 0's. In other words, computing the busy beaver function for a given .
There are only finitely many Turing machines with states, so we are certain that there exists such a maximum. Computing the Busy beaver function for a given then comes down to solving the halting problem for every single machine with states.
Some variant definitions define it as the number of time steps taken by the machine instead. Wikipedia talks about their relationship, but no patience right now.
The Busy Beaver problem is cool because it puts the halting problem in a more precise numerical light, e.g.:
- the Busy beaver function is the most obvious uncomputable function one can come up with starting from the halting problem
- the Busy beaver scale allows us to gauge the difficulty of proving certain (yet unproven!) mathematical conjectures
Busy Beaver Challenge Updated 2025-07-16
Project trying to compute BB(5) once and for all. Notably it has better presentation and organization than any other previous effort, and appears to have grouped everyone who cares about the topic as of the early 2020s.
Very cool initiative!
By 2023, they had basically decided every machine: discuss.bbchallenge.org/t/the-30-to-34-ctl-holdouts-from-bb-5/141
Finite special general linear group Updated 2025-07-16
Just like for the finite general linear group, the definition of special also works for finite fields, where 1 is the multiplicative identity!
Note that the definition of orthogonal group may not have such a clear finite analogue on the other hand.
Mathematics illustration software Updated 2025-07-16
Survey by Ciro Santilli: math.stackexchange.com/questions/1985/software-for-drawing-geometry-diagrams/3938216#3938216
Many plotting software can be used to create mathematics illustrations. They just tend to have more data-oriented rather than explanatory-oriented output.
SQL SERIALIZABLE isolation level Updated 2025-07-16
First block not mined by Satoshi Updated 2025-07-16
Mathy Magic: The Gathering thoughts Updated 2025-07-16
In 2019, a paper proved that MTG is Turing complete with a legacy legal deck. Live demo with some hand waving: Video "I Built a COMPUTER in Magic: The Gathering by Because Science (2019)". As Ciro Santilli comments at: github.com/cirosantilli/cirosantilli.github.io/issues/42 this was an interest addition to the previous "indefinite infinite loop" e.g. as found in a Four Horsemen combo deck
Asian fetish Updated 2025-07-16
Whenever Ciro's wife starts with "the Asian fetish talk", Ciro reminds her of her own claimed "tall person fetish", and they call it quits.
Asian fetish is much more than sex. It is about the culture, the history, the language. It is the same fetish that makes great mathematicians an Artists do what they do.
When Ciro Santilli was at École Polytechnique, he had to do a presentation for his stupid English courses that all students were forced to take, no matter how good their English was.
The topic was likely something like "pick a country", and Ciro was delighted when he managed to pick "China", after it had gone around a table with many many people before him.
The PowerPoint presentation Ciro made over the weekend was so amazing (and making it was actually fun to make, Ciro actually remembers it a bit!), drawing partly from stuff his wife then girlfriend showed him, that at the end the one of the other students asked him if he had lived in China.
It is a shame Ciro couldn't find the presentation when he wrote this line many many years later. Anything that is not in a BLOB-free monorepo, will disappear, heed my words. But he's certain about two things which it contained:
en.wikipedia.org/wiki/Asian_fetish#History_of_originssubservient, passive, mysterious are understandable. But Hyper-sexual and villainous? OMG have these people never seen real Asians?
en.wikipedia.org/wiki/Asian_fetish#Pornography:
In the United States, women of East and Southeast Asian descent are sometimes stereotyped as subservient, passive, mysterious, villainous in nature, and hyper-sexual.
en.wikipedia.org/wiki/Asian_fetish#Pornography:
Open source standard cell library Updated 2025-07-16
Open source ones:
- www.quora.com/Are-there-good-open-source-standard-cell-libraries-to-learn-IC-synthesis-with-EDA-tools/answer/Ciro-Santilli Are there good open source standard cell libraries to learn IC synthesis with EDA tools?
Pivot (strategy) Updated 2025-07-16
Spectral line Updated 2025-07-16
A single line in the emission spectrum.
Has been the leading motivation of the development of quantum mechanics, all the way from the:
- Schrödinger equation: major lines predicted, including Zeeman effect, but not finer line splits like fine structure
- Dirac equation: explains fine structure 2p spin split due to electron spin/orbit interactions, but not Lamb shift
- quantum electrodynamics: explains Lamb shift
- hyperfine structure: due to electron/nucleus spin interactions, offers a window into nuclear spin
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