Ciro Santilli @cirosantilli 40

are faster to create and edit
uses less disk space and network bandwidth
is easier to search: Ctrl + F on the browser and off you go. And then grep if you have superpowers.

Only produce video material if:

it shows an experiment, physical technique, natural phenomena or location that is of interest. See also: Section "Videos of all key physics experiments"
it gives fundamental geometric insight on the subject
you are filming a human transmitting their passion about the subject, and the speaker is amazing, and does not speak for too long

Never create videos of people just speaking hardcore content for long amounts of time.

If you have to use videos, make them as short as possible, and index them with a textual table of contents.

Also consider using sequences of images or GIFs instead of videos, since those are cheaper.

Figure 1.
Textbooks Y U NO HAVE CTRL-F meme
. Source. Same applies to videos.

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555 timer IC Updated 2025-07-16

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How to teach / Use English Updated 2025-07-16

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By writing in English you reach more people.

Writing in any other language is a waste of time.

The reason is simple: English speakers control a huge proportion of the world's GDP.

English is the de-facto Lingua Franca of the second half of the 20th Century, it is the new lingua franca, the new Latin, and there is no escaping it.

Students who don't know English will never do anything truly useful in science and technology. So it is pointless to teach them anything (besides English itself).

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How to write technical help requests and bug reports Updated 2025-07-16

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Ciro Santilli often sees all those genius who are much smarter than him making shitty forum/mailing list posts, they need to learn this:

The apparently most important one liner error message must appear in the title, and fuller apparently relevant logs must appear on the body
You must always give the version of the software that you are using as either a tag or git SHA
These are an important part of the minimal working example.
For build errors, you must give your OS and compiler version and version of any relevant external library

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5S ribosomal RNA Updated 2025-07-16

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HTML canvas Updated 2025-07-16

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developer.mozilla.org/en-US/docs/Web/API/Canvas_API

Allows us to draw with JavaScript pixel by pixel! Great way to create computational physics demos!

Here is an animation demo with some useful controls:

HTML snippet:

new class extends OurbigbookCanvasDemo {
  init() {
    super.init('hello');
    this.pixel_size_input = this.addInputAfterEnable(
      'Pixel size',
      {
        'min': 1,
        'type': 'number',
        'value': 1,
      }
    );
  }
  draw() {
    var pixel_size = parseInt(this.pixel_size_input.value);
    for (var x = 0; x < this.width; x += pixel_size) {
      for (var y = 0; y < this.height; y += pixel_size) {
        var b = ((1.0 + Math.sin(this.time * Math.PI / 16)) / 2.0);
        this.ctx.fillStyle =
          'rgba(' +
          (x / this.width) * 255 + ',' +
          (y / this.height) * 255 + ',' +
          b * 255 +
          ',255)'
        ;
        this.ctx.fillRect(x, y, pixel_size, pixel_size);
      }
    }
  }
}

Bibliography: developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Basic_animations">https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Basic_animations

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Stockfish CLI Updated 2025-10-14

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www.maketecheasier.com/use-stockfish-cli-master-chess is a good source.

Most of what follows is part of the Universal Chess Interface. Tested on Ubuntu 22.10, Stockfish 14.1.

After starting stockfish on the command line, d (presumably display) contains:

 +---+---+---+---+---+---+---+---+
 | r | n | b | q | k | b | n | r | 8
 +---+---+---+---+---+---+---+---+
 | p | p | p | p | p | p | p | p | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 5
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 3
 +---+---+---+---+---+---+---+---+
 | P | P | P | P | P | P | P | P | 2
 +---+---+---+---+---+---+---+---+
 | R | N | B | Q | K | B | N | R | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
Key: 8F8F01D4562F59FB

Sweet ASCII art. where:

Fen: FEN notation
Key: TODO

Move white king's pawn from e2 to e4:

position startpos moves e2e4

Then display again:

gives:

 +---+---+---+---+---+---+---+---+
 | r | n | b | q | k | b | n | r | 8
 +---+---+---+---+---+---+---+---+
 | p | p | p | p | p | p | p | p | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 5
 +---+---+---+---+---+---+---+---+
 |   |   |   |   | P |   |   |   | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 3
 +---+---+---+---+---+---+---+---+
 | P | P | P | P |   | P | P | P | 2
 +---+---+---+---+---+---+---+---+
 | R | N | B | Q | K | B | N | R | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1
Key: B46022469E3DD31B

so we see that the pawn moved.

Now let's make Stockfish think for one second what is the next best move for black:

go movetime 1000

gives as the last line:

bestmove c7c5 ponder g1f3

TODO:

what is ponder? Something to do with thinking on the opponent's turn: permanent brain.
understand the previous lines

To make the move it as suggested for black, we have to either repeat the entire sequence of movements:

position startpos moves e2e4 c7c5

d:

 +---+---+---+---+---+---+---+---+
 | r | n | b | q | k | b | n | r | 8
 +---+---+---+---+---+---+---+---+
 | p | p |   | p | p | p | p | p | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   |   | p |   |   |   |   |   | 5
 +---+---+---+---+---+---+---+---+
 |   |   |   |   | P |   |   |   | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 3
 +---+---+---+---+---+---+---+---+
 | P | P | P | P |   | P | P | P | 2
 +---+---+---+---+---+---+---+---+
 | R | N | B | Q | K | B | N | R | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2
Key: 4CA78BCE9C2980B0

or alternatively we could also use the previous FEN notation as a starting point;

position fen rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1 moves c7c5

Note how the Universal Chess Interface interface is very simple: we just load a state and then decide what to do next for that one state. The engine holds only one and exactly one state at a time, and you can't even modify it differentially without loading new one from scratch.

Let's move white again with our brain with either:

position startpos moves e2e4 c7c5 d2d3
position fen rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2 moves d2d3

Set a specific position from fen:

position fen rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1

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Huainanzi Updated 2025-07-16

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De novo DNA synthesis Updated 2025-07-16

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As of 2018, Ciro Santilli believes that this could be the next big thing in biology technology.

"De novo" means "starting from scratch", that is: you type the desired sequence into a computer, and the synthesize it.

The "de novo" part is important, because it distinguishes this from the already well solved problem of duplicating DNA from an existing DNA template, which is what all our cells do daily, and which can already be done very efficiently in vitro with polymerase chain reaction.

Many companies are attempting to create more efficient de novo synthesis methods:

Notably, the dream of most of those companies is to have a machine that sits on a lab bench, which synthesises whatever you want.

TODO current de novo synthesis costs/time to delivery after ordering a custom sequence.

The initial main applications are likely going to be:

polymerase chain reaction primers (determine which region will be amplified
creating a custom sequence to be inserted in a plasmid, i.e. artificial gene synthesis

but the real pipe dream is building and bootstraping entire artificial chromosomes

News coverage:

2023-03 twitter.com/sethbannon/status/1633848116154880001
AnsaBio created the world's longest DNA oligo produced using de novo synthesis! 1,005 bases! 99.9% stepwise yield
2020-10-05 www.nature.com/articles/s41587-020-0695-9 "Enzymatic DNA synthesis enters new phase"

Video 1.

Nuclera eDNA enzymatic de novo DNA synthesis explanatory animation (2021)

Source. The video shows nicely how Nuclera's enzymatic DNA synthesis works:

they provide blocked nucleotides of a single type
add them with the enzyme. They use a werid DNA polymerase called terminal deoxynucleotidyl transferase that adds a base at a time to a single stranded DNA strand rather than copying from a template
wash everything
do deblocking reaction
and then repeat until done