Domain name speculation by Ciro Santilli 35 Updated +Created
Bilinear map by Ciro Santilli 35 Updated +Created
Linear map of two variables.
More formally, given 3 vector spaces X, Y, Z over a single field, a bilinear map is a function from:
that is linear on the first two arguments from X and Y, i.e.:
Note that the definition only makes sense if all three vector spaces are over the same field, because linearity can mix up each of them.
The most important example by far is the dot product from , which is more specifically also a symmetric bilinear form.
Term symbol by Ciro Santilli 35 Updated +Created
This notation is so confusing! People often don't manage to explain the intuition behind it, why this is an useful notation. When you see Indian university entry exam level memorization classes about this, it makes you want to cry.
The key reason why term symbols matter are Hund's rules, which allow us to predict with some accuracy which electron configurations of those states has more energy than the other.
web.chem.ucsb.edu/~devries/chem218/Term%20symbols.pdf puts it well: electron configuration notation is not specific enough, as each such notation e.g. 1s2 2s2 2p2 contains several options of spins and z angular momentum. And those affect energy.
This is why those symbols are often used when talking about energy differences: they specify more precisely which levels you are talking about.
Basically, each term symbol appears to represent a group of possible electron configurations with a given quantum angular momentum.
We first fix the energy level by saying at which orbital each electron can be (hyperfine structure is ignored). It doesn't even have to be the ground state: we can make some electrons excited at will.
The best thing to learn this is likely to draw out all the possible configurations explicitly, and then understand what is the term symbol for each possible configuration, see e.g. term symbols for carbon ground state.
It also confusing how uppercase letters S, P and D are used, when they do not refer to orbitals s, p and d, but rather to states which have the same angular momentum as individual electrons in those states.
It is also very confusing how extremelly close it looks to spectroscopic notation!
The form of the term symbol is:
The can be understood directly as the degeneracy, how many configurations we have in that state.
Video 1.
Atomic Term Symbols by TMP Chem (2015)
Source.
Video 2.
Atomic Term Symbols by T. Daniel Crawford (2016)
Source.
Don Lincoln by Ciro Santilli 35 Updated +Created
Publishes through the Fermilab YouTube channel under the playlist "Fermilab - Videos by Don Lincoln"
Some insights, but too much on the popular science side of things.
Academia is broken by Ciro Santilli 35 Updated +Created
Sometimes Ciro Santilli regrets not having done a PhD. But this section makes him feel better about himself. To be fair, part of the merit is on him, part of the reason he didn't move on was the strong odour of bullshit oozing down to Masters level. A good PhH might have opened interesting job opportunities however, given that you don't really learn anything useful before that point in your education.
twitter.com/togelius/status/1584611702691483648:
The "real world" is full of people who couldn't make it in academia.
Video 1.
I failed in academia by Andy Stapleton (2021)
Source.
Video 2.
6 Dirty Tactics Found In Academia & Universities by Andy Stapleton (2022)
Source.
Video 3.
Rise to the Top: The Habits and Mindset of Top 0.1% PhD Students by Andy Stapleton (2023)
Source.
Figure 1.
Profzi scheme by PhD Comics
.
A Ponzi scheme that trains people in new skills is not necessarily a terrible thing. It is a somewhat more useful version than standard exam based education.
Perhaps the problem is "forcing" 35 year olds to go down that path when they might also want to have boring stuff like families and security.
If people could get to the PhD level much, much sooner, it wouldn't be as obscene: Section "Students must be allowed to progress as fast as they want".
Video 4.
The broken system at the heart of Academia by Peter Judo (2023)
Source.
Video 5.
My dream died, and now I'm here by Sabine Hossenfelder (2024)
Source.
Video 6.
I left academia. Here's why. by Jared Henderson
. Source.
Blood by Ciro Santilli 35 Updated +Created
CIFAR-10 by Ciro Santilli 35 Updated +Created
60,000 32x32 color images in 10 different classes: airplanes, cars, birds, cats, deer, dogs, frogs, horses, ships, and trucks.
TODO release date.
This dataset can be thought of as an intermediate between the simplicity of MNIST, and a more full blown ImageNet.
List of High-temperature superconductors by Ciro Santilli 35 Updated +Created
Classification of finite simple groups by Ciro Santilli 35 Updated +Created
Ciro Santilli is very fond of this result: the beauty of mathematics.
How can so much complexity come out from so few rules?
How can the proof be so long (thousands of papers)?? Surprise!!
And to top if all off, the awesomely named monster group could have a relationship with string theory via the monstrous moonshine?
The classification contains:
Video 1.
Simple Groups - Abstract Algebra by Socratica (2018)
Source. Good quick overview.
Palo Alto by Ciro Santilli 35 Updated +Created
Snakes and Ladders by Ciro Santilli 35 Updated +Created
"Game" is a bit of a stretch as there are no player choices at all.
A more precise word would be simulation.
More precise, this "game" is exactly an absorbing Markov chain.
Average length of a Snakes and Ladders game by Ciro Santilli 35 Updated +Created
Since Snakes and Ladders is nothing but a Absorbing Markov chain, the results are exactly the same as for that general problem.
www.jstor.org/stable/3619261: How Long Is a Game of Snakes and Ladders? by Althoen, King and Schilling (1993), paywalled.
Magic Aids by Ciro Santilli 35 Updated +Created
His combination of politically incorrect dirt talk with amazing quirky decks captures Ciro's imagination.
Anonymous no face-reveal.
The videos are heavily edited with all pauses cut out, which makes them very quick to watch and saves viewer time.
Modern focused, with some occasional newer formats mixed in.
When Wizards publishes several useless sets in a row without a single modern playable card, he's just forced into Standard.
Video 1.
Magic Aids vs. Magic Rainbows by Magic Aids (2018)
Source. In this amazing video Magic Aids makes fun of Wizards for forcing him to change is Magic Online handle from Magic Aids to something else due to the AIDS part. He claims the Aids is not meant as a reference to the disease, but just as in "memory aid". Ciro doubts this wasn't intentional. But the video is still amazing, and happens to involve a sex doll dressed as Liliana Vess squirting glitter from her vagina. Wizards must love this guy. It is also a good criticism of political correctness in general. This is a work of art.
Model organism by Ciro Santilli 35 Updated +Created
Basal (phylogenetics) by Ciro Santilli 35 Updated +Created
When a characteristic is basal, it basically means the opposite of it being polyphyletic.
E.g. monotremes laying eggs did not evolve separately after function loss, it comes directly from reptiles.
Magarena by Ciro Santilli 35 Updated +Created
Open source MtG engine implementation written in Java.
Seems to have an option to download art from internet as well.
Ciro Santilli wonders how legal it is. They very explicitly do not mention the words Magic: The Gathering anywhere.
Their UI does a good job at being self explanatory. Space is the shortcut to skip phases.
No online play.
TODO it appears to parse card functionality out of the human readable text! That's genius, as it helps automatically get new cards working, and squirt around legal issues.
Pinned article: ourbigbook/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!
Video 1.
Intro to OurBigBook
. Source.
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
    Video 2.
    OurBigBook Web topics demo
    . Source.
  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:
    • to OurBigBook.com to get awesome multi-user features like topics and likes
    • as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
    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.
    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