Ciro Santilli @cirosantilli 40

Why was this so rarely used as of 2020s compared to ISBNs? It would have been perfect for helping find obscure records from Chinese traditional music and Indian classical music!

But instead we have Discogs, which is not too bad.

They died so completely, Googling "ICL" now has higher hits such as Imperial College London.

The different only shows up for field, not with particles. For fields, there are two types of changes that we can make that can keep the Lagrangian unchanged as mentioned at Physics from Symmetry by Jakob Schwichtenberg (2015) chapter "4.5.2 Noether's Theorem for Field Theories - Spacetime":

From defining properties of elementary particles:

From the spacetime theory alone, we can derive the Lagrangian for the free theories for each spin:Then the internal symmetries are what add the interaction part of the Lagrangian, which then completes the Standard Model Lagrangian.

Source: github.com/QBobWatson/ila.

Written in MathBook XML.

Used a lot in quantum mechanics, where the equations are really hard to solve. There's even a dedicated wiki page for it: en.wikipedia.org/wiki/Perturbation_theory_(quantum_mechanics). Notably, Feynman diagrams are a way to represent perturbation calculations in quantum field theory.

Let's gather some of the best results we come across here:

The period does depend on the initial height/angle, except for the very small angle approximation:

Because there is value in tutorials written by beginners:

Initially a phenomenological guess to explain the periodic table. Later it was apparently proven properly with the spin-statistics theorem, physics.stackexchange.com/questions/360140/theoretical-proof-of-paulis-exclusion-principle.

And it was understood more and more that basically this is what prevents solids from collapsing into a single nucleus, not electrical repulsion: electron degeneracy pressure!

Bibliography:

IDEs are absolutely essential for developing complex software.

The funny thing is that you don't notice this until someone shows it to you. But once you see it, there is not turning back, just like Steve Jobs customers don't know what they want quote.

Unfortunately, after the Fall of Eclipse (archive), the IDE landscape in 2019 is horrible and split between:

Programmers of the world: unite! Focus on one IDE, and make it work for all languages and all build systems. Give it all the features that Eclipse has, but none of the bugginess. Work with top project to make sure the IDE works for all top projects.

Projects of the world: support one IDE, with in-tree configuration. Complex integration is often required between the IDE and the build system, and successful projects must to that once for all developers. Either do this, or watch you complex project wither away.

Build tool maintainers: make it possible for IDEs to support your tool! E.g., implement JSON Compilation Database output so that IDEs can read the exact compiler commands from that, in order to automatically determine how files should be parsed! Or better, just use libllvm in your IDE itself as the main parser.

Ciro is evaluating some IDEs at: github.com/cirosantilli/ide-test-projects

The main interface between the central processing unit and software.

This is the order in which a binary search tree should be traversed for ordered output, i.e.:

This ordering makes sense for binary trees and not k-ary trees in general because if there are more than two nodes it is not clear what the top node should go in the middle of.

This is unlike pre-order depth-first search and post-order depth-first search which generalize obviously to general trees.

Mnemonic: in means into. So we are going into a codomain that is large enough so that we can have a different image for every input.

Currently an informal name for the Standard Model

Chronological outline of the key theories: