OpenCourseWare Updated +Created
Potentiometer Updated +Created
Literature Updated +Created
Ciro Santilli used to read books when he was younger (Harry Potter up to the 4th, Lord of the Rings), but once you are reading code, technical articles and news the whole day, you really just want to watch videos of people doing useless things on YouTube to rest, enough text.
Books are slow. No patience. Need faster immediate satisfaction.
Paradoxically Ciro feels like he's becoming a writer of sorts though, one semi independent section/answer/piece of knowledge at a time.
Writing is not just giving out information. It is re-feeling it.
Lorentz group Updated +Created
Subgroup of the Poincaré group without translations. Therefore, in those, the spacetime origin is always fixed.
Or in other words, it is as if two observers had their space and time origins at the exact same place. However, their space axes may be rotated, and one may be at a relative speed to the other to create a Lorentz boost. Note however that if they are at relative speeds to one another, then their axes will immediately stop being at the same location in the next moment of time, so things are only valid infinitesimally in that case.
This group is made up of matrix multiplication alone, no need to add the offset vector: space rotations and Lorentz boost only spin around and bend things around the origin.
One definition: set of all 4x4 matrices that keep the Minkowski inner product, mentioned at Physics from Symmetry by Jakob Schwichtenberg (2015) page 63. This then implies:
The Godfather Updated +Created
www.youtube.com/playlist?list=PLVV0r6CmEsFzCodipONmNiROhYCUWyz_U interview with Walter Murch by Web of Stories. He worked on sound design for all The Godfather films, and tells some interesting details about it. He's just super nice in general otherwise. E.g.:
Video 1.
Francis Coppola's Notebook on The Godfather
. Source.
By looking at this more general point of view, we could ask ourselves what happens to the group if instead of the dot product we took a more general bilinear form, e.g.:
The answers to those questions are given by the Sylvester's law of inertia at Section "All indefinite orthogonal groups of matrices of equal metric signature are isomorphic".
In 2020 Brazil for example, you are not allowed in theory to obtain a double nationality which you were not allowed to have as a birth right.
This means that Brazilian students e.g. in France, many of whom could easily obtain the French citizenship had to either chose between:
  • giving up their Brazilian citizenship. Who the fuck would do that? Brazilians love their country despite all!
  • not getting French citizenship. This meant in France having to come 6 AM once a year to some police station on some suburbia to stamp a piece of paper, plus having your VISA completely dependant on your employer for several years until you could obtain a permanent VISA, making it very hard to change jobs, and putting you in a constantly precarious position
  • keeping both citizenships, ignoring Brazilian law, which is extremely unlikely to sue you anyways for this bullshit law, and just hope for the best
Can you guess which option Brazilian students would usually pick?
As a poor country, you have to allow people to obtain multiple citizenship. Students are not going to go back because they don't have the foreign citizenship. They are just going to have to ensure shittier jobs for a few years, thus diminishing the chances that they will actually lean anything useful to bring back to your country later on.
XMPP Updated +Created
This was one of the only bad experience Ciro had at Polytechnique, besides the inevitable fear of not graduating.
But the head of the applied mathematics department Polytechnique prevented him from going because Ciro didn't have the necessary grades, even though the Germans had already agreed to it: he had a C, but he needed a B. As mentioned at École Polytechnique, most Brazilians had crappy grades due to their Polytechnique-incompatible background.
This was done because in the past students with bad grades had abandoned their internships halfway and given foreigners a bad impression of Polytechnique.
It is impossible to say if the head of department really agreed with this bullshit policy, or if it was something beyond his powers and he hid his true opinion, but it felt like the agreed.
What an extremely limited view!!!
To leave the worse, the worse. To assume that grades mean anything!
And thus Ciro had to choose a last moment internship that he hated, rather than becoming the greatest roboticist that ever lived, and did terribly at it.
At least on the other hand Ciro learnt Python instead of working at the internship, and became the greatest programming tutorial writer that ever lived. Maybe.
Wireless Updated +Created
Brain-computer interface company Updated +Created
Gas chromatography etymology Updated +Created
The name makes absolutely no sense in modern terms, as nor colors nor light are used directly in the measurements. It is purely historical.
Messier object Updated +Created
What an awesome list the dude compiled. Contains many of the features we care the most about of the sky, since of course, apparent magnitude is a big determinant of that.
Planetary system Updated +Created
The Harvest of a Century by Siegmund Brandt (2008) Updated +Created
This is a good book, it gives a summary of biographies, and a reasonable description of the main ideas, with many illustrations. Each subject is not presented in incredible detail, but it is a good overview of events.
Fictional pornography depicting minors Updated +Created
This is the kind of mind-bending argument twists that Ciro Santilli loves. If we take out the "a real child is hurt" aspect, does it still make sense to make it illegal?
Of course, hentai of young-looking girls has already existed since forever. Bit with newer image generation methods in the 2020s used for computer generated child pornography, especially sometimes photorealistic text-to-image generation, things are taken to another level.
Global Positioning System Updated +Created
They actually carry atomic clocks in them.
Johann Joseph Loschmidt Updated +Created

There are unlisted articles, also show them or only show them.