User talk:Thubsch

October 2014

Please do not add promotional material to Wikipedia. While objective prose about beliefs, products or services is acceptable, Wikipedia is not intended to be a vehicle for soapboxing, advertising or promotion. Thank you. Alexf^(talk) 12:14, 10 October 2014 (UTC)

Conceptual Hierarchy

The conceptual organization of this page is ...ahem...backwards. The introductory sentence, "Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles" is just plain false: Quantum mechanics does not include quantum field theory, it's the other way around! Also, there is some imprecision (conflation and equivocation) since "quantum mechanics" is most often thought of as "non-relativistic quantum mechanics," while "quantum field theory" is most often thought of as "relativistic quantum field theory." Thereby,

1. "non-relativistic quantum mechanics" is the "c→∞" limit of the "relativistic quantum mechanics" (this used mostly only in high-energy/particle physics),
2. "relativistic quantum mechanics" is the "constant number (typically, ONE!) of quanta" special case of "relativistic quantum field theory".

To wit, QM cannot incorporate quantum-particle decay or creation, as that would violate probability conservation: The state-operator (or -function, for pure states) is normalized. There is also "many-body quantum mechanics" (logically, both non-relativistic and relativistic), which still has a fixed number (>1) of quanta...

Also, rather than "quantum theory" being equivalent (and so redirecting to) "quantum mechanics," the term "quantum theory" is logically and in practice an umbrella-term (and so a fake singular) including the "nrQM ⊂ rQM ⊂ QFT" sequence of inclusions, but also "string theory" (which is a layer-cake of quantum field theories: #1→ 1+1-dimensional worldsheet QFT, #2→ 9+1-dimensional target space QFT, #3→ n-dimensional moduli space QFT, ...), but also "loop quantum gravity" (with its somewhat different approach to quantization, which may or may not end up being corrected and/or shown to be equivalent to the standard sequence of canonical-BRST-BV quantization frameworks), as well as the "semi-classical" and "effective field theory" as its approximating frameworks.

Rewriting this (and perhaps some related) page(s) as well as correcting the various redirects is waaay above my wiki-knowledge.

There is however a cheap way out: by stating that "non-relativistic quantum mechanics" is the common denominator of all various quantum theories; that is to say, "non-relativistic quantum mechanics" should be thought of as the common special case of all various quantum theories, whereby all other quantum theories are (various) extensions of quantum mechanics. Tristan (talk) 21:01, 17 July 2018 (UTC)