Sal Khan Updated 2025-07-16
Like Jimmy Wales, he used to work in finance and then quit. What is it with those successful e-learning people??
Sass (stylesheet language) Updated 2025-07-16
The more of their syntax gets merged into mainline Cascading Style Sheets, the better the world will be.
Leo Szilard Updated 2025-07-16
Video 1.
Leo Szilard: The Genius Behind the Bomb
. Source. 1992. TODO an external link to the production? Producers credited at end: Helen Weiss and Alain Jehlen. As indicated at: archive.org/details/TheGeniusBehindtheBomb it was apparently produced by WGBH, public radio station from Boston.
Level: Asian Updated 2025-07-16
This is true. The level of competition in university entry exams in Asia in insane in the early 21st century compared to the West.
Life difficulty level meme Updated 2025-07-16
TODO there was one which was relly good, can't find it anymore. One day.
Figure 1.
Life difficulty level meme with West Europe, East Europe, Turkey and Middle east
. Source.
Planned obsolescence Updated 2025-07-16
The first time Ciro Santilli Googled this was when trying to repair his cell phone.
2019 cell phones are glued together with adhesive, which makes them impossible to repair them unless you have a heat gun, spend hours and hours learning and planning, and accept the risk of breaking the screen
If you take a phone less than 300 dollars to a repair shop in the first world, they will say: I've never repaired this crap, and likely for the price of the repair you should just buy a new one, and so to the trash goes the old one, polluting the planet, and in comes a new one, enriching the manufacturer further.
Pleistocene Updated 2025-07-16
Agriculture is not the official definition of the age. But it is good enough. Likely related to the official end of glaciations thing.
Second law of thermodynamics Updated 2025-07-16
Subtle is the Lord by Abraham Pais (1982) chapter 4 "Entropy and Probability" mentions well how Boltzmann first thought that the second law was an actual base physical law of the universe while he was calculating numerical stuff for it, including as late as 1872.
But then he saw an argument by Johann Joseph Loschmidt that given the time reversibility of classical mechanics, and because they were thinking of atoms as classical balls as in the kinetic theory of gases, then there always exist a valid physical state where entropy decreases, by just reversing the direction of time and all particle speeds.
So from this he understood that the second law can only be probabilistic, and not a fundamental law of physics, which he published clearly in 1877.
Second quantization Updated 2025-07-16
Second quantization also appears to be useful not only for relativistic quantum mechanics, but also for condensed matter physics. The reason is that the basis idea is to use the number occupation basis. This basis is:
Bibliography:
Linear operator Updated 2025-07-16
We define it as a linear map where the domain is the same as the image, i.e. an endofunction.
Examples:

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