LevelDB Updated 2025-07-16
One "LevelDB" database contains multiple file in a directory. Off the bat inferior to SQLite which stores everything in a single file!
OpenUSD Updated 2025-07-16
useCallback Updated 2025-07-16
Quantum mechanics Updated 2025-07-16
Quantum mechanics is quite a broad term. Perhaps it is best to start approaching it from the division into:
Mathematics: there are a few models of increasing precision which could all be called "quantum mechanics":
Ciro Santilli feels that the largest technological revolutions since the 1950's have been quantum related, and will continue to be for a while, from deeper understanding of chemistry and materials to quantum computing, understanding and controlling quantum systems is where the most interesting frontier of technology lies.
Web portal Updated 2025-07-16
Quantum electrodynamics Lagrangian Updated 2025-07-16
where:
Note that this is the sum of the:
Note that the relationship between and is not explicit. However, if we knew what type of particle we were talking about, e.g. electron, then the knowledge of psi would also give the charge distribution and therefore
Video 1.
Particle Physics is Founded on This Principle! by Physics with Elliot (2022)
Source.
Bitcoin Core snap Updated 2025-07-16
Officially supported installation method on Ubuntu 23.10.
Racing game Updated 2025-07-16
Quote by Ciro Santilli Updated 2025-07-16
These are "original" thoughts that Ciro had which at some point in the past amused him. Some would call them pieces of wisdom, others self delusion. All have likely been thought by others in the past, and some of them Ciro thinks to himself after a few years: "why did I like this back then??".
After Ciro's colleague was doing that in a project:
On the theory vs practice of computer science:
Whereas Turing completeness is enough for mathematicians, humans need "run-on-Debian-complete".
On how human perception of media is completely unrelated to the computer's transmission mechanism:
Media for humans is not byte streams. It is magic.
On how you make the best friends in life when dealing with hardships together.
The bond between men is like the bond between two metals: it is better made under fire.
In Ciro's case, this in particular means going through high school/universities studies and work projects, though of course war would apply particularly well. Perhaps inspired by as iron sharpens iron, so one person sharpens another.
This is of course just another version of one picture is worth a thousand words.
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.
Is the only atom that has a closed form solution, which allows for very good predictions, and gives awesome intuition about the orbitals in general.
It is arguably the most important solution of the Schrodinger equation.
In particular, it predicts:
The explicit solution can be written in terms of spherical harmonics.
Video 1.
A Better Way To Picture Atoms by minutephysics (2021)
Source. Renderings based on the exact Schrödinger equation solution for the hydrogen atom that depict wave function concentration by concentration of small balls, and angular momentum by how fast the balls rotate at each point. Mentions that the approach is inspired by de Broglie-Bohm theory.

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