Why do mathematicians and physicist use the words “elementary” and “introduction” for advanced textbooks in the field? Is it to flex intellectual powress?
“Elementary” doesn’t mean “what you learned in elementary school,” although it is publically perceived as such.
Almost universally, in almost every text I’ve read, it means “use tools that are well-known to people with an undergraduate degree in a related field, or simple extensions thereof.” (There are some cheeky counter-examples, such as Weil’s Basic Number Theory, but this is far more rare.)
In the same way you cannot expect someone who has never seen a circuit or understand logic gates to construct a processor, you cannot expect someone without any mathematical maturity (e.g. basic linear algebra and calculus) to use QM in any fashion other than understand the most basic of constructions.
