Ciro Santilli @cirosantilli 35

Originally done with (neutral) silver atoms in 1921, but even clearer theoretically was the hydrogen reproduction in 1927 by T. E. Phipps and J. B. Taylor.

The hydrogen experiment was apparently harder to do and the result is less visible, TODO why: physics.stackexchange.com/questions/33021/why-silver-atoms-were-used-in-stern-gerlach-experiment

Related to what does it mean that photons are force carriers for electromagnetism?.

Two lower case variants... both used in mathematical notation, and for some reason, in LaTeX \varphi is the one that actually looks like the default standard modern lowercase phi, while \phi is the weird one. I love life.

More interestingly, how is that implied by the Stern-Gerlach experiment?

physics.stackexchange.com/questions/266359/when-we-say-electron-spin-is-1-2-what-exactly-does-it-mean-1-2-of-what/266371#266371 suggests that half could either mean:

This is a pain point as of SVG 1.1...

Examples at svg/background.html which answers from stackoverflow.com/questions/11293026/default-background-color-of-svg-root-element/11293812:

This pain reflects directly on Inkscape: set SVG background color in Inkscape.

This vocabulary likely entered Ciro Santilli's vernacular through playing Counter-Strike when he was a teenager.

Existence and uniqueness results are fundamental in mathematics because we often define objects by their properties, and then start calling them "the object", which is fantastically convenient.

But calling something "the object" only makes sense if there exists exactly one, and only one, object that satisfies the properties.

One particular context where these come up very explicitly is in solutions to differential equations, e.g. existence and uniqueness of solutions of partial differential equations.