Pions were a revolutionary discovery in the 1930s — among the first animals in the ‘particle zoo’ — but here I’m explaining them as a way to work toward the math and physics concepts needed for the Standard Model.

As soon as the neutron was discovered in 1932, Heisenberg invented the idea of ‘isospin’, and the idea that the proton and neutron are two different isospin states of a single particle: the nucleon. This is why I explained the math of spin-1/2 particles in earlier videos: in order to talk about isospin.

Three years later, Yukawa came up with the idea that the force holding nuclei together is carried by a new particle. Even better, he predicted the mass of this yet-unseen particle!

Later, the pion was discovered: in fact, three kinds of pions. Heisenberg realized how these were connected to the 3 Pauli matrices, and this was a big step toward the modern theory of gauge bosons.

(For mathematicians: pions are a basis of the Lie algebra 𝔰𝔩(2,ℂ). 🤯)

https://www.youtube.com/watch?v=AC7K7SFDNK0&list=PLuAO-1XXEh0Zy7uUbyrTc2SIz3dB-bcfR

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Including scientific publishing, pharmaceutical industry, online information, and commercial scientific software: https://www.rsccicag.org/index_htm_files/CICAG%20Distillate%20Winter%202025-26%20FINAL.pdf

Contribution from: Phil McHale, MRSC

Omtrent således så det ud, hvis man nu kiggede mod Christiansborg fra Gammel Strand en solskinsdag i 1868 (eller deromkring). Heldigvis var 47-årige Henrich Hansen (1821-1890) på pletten, og hans 260 cm brede maleri har boet i museets samling lige siden.
God morgen og rigtig god valgdag derude! 🗳️

📍https://open.smk.dk/map?center=KMS863#15/55.67565/12.57548
🔎 https://open.smk.dk/artwork/iiif/KMS863

Mere Christiansborg i samlingen: https://open.smk.dk/art?q=christiansborg&filters=has_image%3Atrue

The International Congress of Mathematicians (#ICM) decided not to meet in #Russia in 2022, for a list of reasons including Russa's "war of aggression in #Ukraine and the potential dangers…in regards to freedom of political expression and the safety of #LGBTQ participants." Now some ICM members have launched a petition asking it not to meet in the US in 2026, for a list of reasons including US aggression in #Gaza, #Greenland, #Iran, and #Venezuela, and "serious concern that academics (or anyone) traveling to the US may be denied entry."
https://docs.google.com/forms/d/e/1FAIpQLSdHJhc8X83b8oL6rH2KDX0I730eraum5I8_IlWY23F82mHuag/viewform?fbzx=7063048079651794343

#Mathematics #USPol #USPolitics