Finite field Updated 2025-07-16
A convenient notation for the elements of of prime order is to use integers, e.g. for we could write:
which makes it clear what is the additive inverse of each element, although sometimes a notation starting from 0 is also used:
For fields of prime order, regular modular arithmetic works as the field operation.
For non-prime order, we see that modular arithmetic does not work because the divisors have no inverse. E.g. at order 6, 2 and 3 have no inverse, e.g. for 2:
we see that things wrap around perfecly, and 1 is never reached.
For non-prime prime power orders however, we can find a way, see finite field of non-prime order.
Video 1.
Finite fields made easy by Randell Heyman (2015)
Source. Good introduction with examples
Finite general linear group Updated 2025-07-16
general linear group over a finite field of order . Remember that due to the classification of finite fields, there is one single field for each prime power .
Exactly as over the real numbers, you just put the finite field elements into a matrix, and then take the invertible ones.
Flash memory Updated 2025-07-16
Video 1.
The Engineering Puzzle of Storing Trillions of Bits in your Smartphone / SSD using Quantum Mechanics by Branch Education (2020)
Source. Nice animations show how quantum tunnelling is used to set bits in flash memory.
Form of government Updated 2025-07-16
Rasselas Prince of Abyssinia CHAPTER VIII www.gutenberg.org/cache/epub/652/pg652-images.html:
Oppression is, in the Abyssinian dominions, neither frequent nor tolerated; but no form of government has been yet discovered by which cruelty can be wholly prevented. Subordination supposes power on one part and subjection on the other; and if power be in the hands of men it will sometimes be abused. The vigilance of the supreme magistrate may do much, but much will still remain undone. He can never know all the crimes that are committed, and can seldom punish all that he knows.
Fourier transform Updated 2025-07-16
Continuous version of the Fourier series.
Of course, every function defined on a finite line segment (i.e. a compact space).
Therefore, the Fourier transform can be seen as a generalization of the Fourier series that can also decompose functions defined on the entire real line.
As a more concrete example, just like the Fourier series is how you solve the heat equation on a line segment with Dirichlet boundary conditions as shown at: Section "Solving partial differential equations with the Fourier series", the Fourier transform is what you need to solve the problem when the domain is the entire real line.
Four Treasures of the Study Updated 2025-07-16
Video 1.
Four Treasures of Chinese Study by a journey of culture (2022)
Source. Over the top and likely without copyright.
Video 2.
Four Treasures of the Study by Li's Ink World (2021)
Source. A more realistic down to Earth one.
University entry exam Updated 2025-07-16
These are the most evil examinations society has.
They mean that until you are 18, you have to study a bunch of generic crap you hate just to get into university. Rather than studying whatever it is that you truly love to become a God at it as fast as possible and have any chance of advancing the field.
And then, if you decide that you want to change, which is not unlikely since you haven't really try to study what you signed up for before then, it can be very hard and time consuming, leading to a bunch of adults with useless degress they will never use at work.
With the invention of the Internet, all teaching material can be free and open source. Only laboratory space has any cost (besides the opportunity cost of participation in actual projects in a research team).
Per-country list: en.wikipedia.org/wiki/List_of_admission_tests_to_colleges_and_universities
University has become a luxury item Updated 2025-07-16
medium.com/left-right/the-education-system-is-about-to-implode-5c95f774b523 The Education System is About to Implode by Nicholas Budny (2020)
Stanford, MIT, Harvard and Oxford are luxury goods in the same sense that a Mercedes-Benz might be, or the latest iPhone. They sell an aesthetic experience that provides the consumer with social status, similar to acquiring expensive clothes or a fancy house.
Video 1.
Bar scene from Good Will Hunting
. Source. This scene is way way overdone. But:
Hero: You wasted $150,000 on an education you coulda got for $1.50 in late fees at the public library.
Bad guy: Yeah, but I will have a degree. And you'll be serving my kids fries at a drive-through on our way to a skiing trip.
University is broken Updated 2025-07-16
You just have to spend a few minutes with students until they complain about the courses or teachers. And you just have to spend a few hours with teachers until they complain about the students or broader system.
University is broken, and everyone knows it. The only question now is finding a viable, "political cash flow positive" path, into something better.
Bibliography:
It is interesting to see how your own ideas shift with time, and Ciro Santilli doesn't think the following are very important anymore, so he was lazy to migrate them.
When he did the original website Ciro was in a "I must show off my skills to get a job mindset", but then after he landed a few jobs he moved to a "CV websites are useless, just do amazing projects and showcase them on your website to help them succeed" mindset.
Business film Updated 2025-07-16
Ciro Santilli defines a "business film" as a film about business, enterprises or entrepreneurship. Political thrillers are closed related as well.
This is one of his favorite film genres!
Some lists:
Quantum number Updated 2025-07-16
However, it very cool that they are actually discovered before the Schrödinger equation, and are present in the Bohr model (principal quantum number) and the Bohr-Sommerfeld model (azimuthal quantum number and magnetic quantum number) of the atom. This must be because they observed direct effects of those numbers in some experiments. TODO which experiments.
E.g. The Quantum Story by Jim Baggott (2011) page 34 mentions:
As the various lines in the spectrum were identified with different quantum jumps between different orbits, it was soon discovered that not all the possible jumps were appearing. Some lines were missing. For some reason certain jumps were forbidden. An elaborate scheme of ‘selection rules’ was established by Bohr and Sommerfeld to account for those jumps that were allowed and those that were forbidden.
This refers to forbidden mechanism. TODO concrete example, ideally the first one to be noticed. How can you notice this if the energy depends only on the principal quantum number?
Video 1.
Quantum Numbers, Atomic Orbitals, and Electron configurations by Professor Dave Explains (2015)
Source. He does not say the key words "Eigenvalues of the Schrödinger equation" (Which solve it), but the summary of results is good enough.
Bounding box Updated 2025-07-16

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