That is, two electrons per atomic orbital, each with a different spin.
As shown at Schrödinger equation solution for the helium atom, they do repel each other, and that affects their measurable energy.
However, this energy is still lower than going up to the next orbital. TODO numbers.
This changes however at higher orbitals, notably as approximately described by the aufbau principle.
Fresnel diffraction Updated 2025-07-16
Near field approximation to Kirchhoff's diffraction formula, i.e. when the plane of observation is near the object diffracting.
Lamp Updated 2025-07-16
Matter.js Updated 2025-07-16
To run the demos locally, tested on Ubuntu 22.10:
git clone https://github.com/liabru/matter-js
cd matter-js
git checkout 0.19.0
npm install
npm run dev
and this opens up the demos on the browser.
sha1sum Updated 2025-07-16
shred (UNIX) Updated 2025-07-16

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