Ciro Santilli @cirosantilli 40

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:

Source: github.com/QBobWatson/ila.

Written in MathBook XML.

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.

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

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.

The term "visible life" refers to multicellular from before people knew there was life in the proterozoic.

Can you do anything with it? What's the license?

We can't see individual stars outside of the Milky Way:Any single star outside of the Milky Way cannot be seen.

The Large Magellanic Cloud stands out as the brightest thing we can see from outside the Milky Way by far!

A web server is mandatory for assets, unless you embed them in data URLs, file:// access is not possible:

Each comic page has an "Emergency Button" below it, which redirects to a mock PDF formatted as a research paper, so you can quickly pretend to be working. Epic.

Can be used to detect single photons.

Richard Feynman likes them, he describes the tube at Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979) at one point.

It uses the photoelectric effect multiple times to produce a chain reaction. In particular, as mentioned at youtu.be/5V8VCFkAd0A?t=74 from Video 1. "Using a Photomultiplier to Detect single photons by Huygens Optics" this means that the device has a lowest sensitive light frequency, beyond which photons don't have enough energy to eject any electrons.