What's the difference between QFT and Atomic physics

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Discussion Overview

The discussion centers on the distinctions between quantum field theory (QFT), atomic physics, nuclear physics, and high energy/particle physics. Participants explore the relationships and applications of these fields, particularly in the context of quantum mechanics and fundamental particle interactions.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants describe atomic physics as the study of atomic interactions, while nuclear physics focuses on nuclear interactions.
  • High energy/particle physics is characterized as the study of fundamental particle interactions.
  • QFT is presented as the underlying mathematical framework for particle interactions, analogous to Newton's laws of motion, with specific theories like QED and QCD derived from it.
  • One participant notes that atomic physics applies quantum mechanics to atoms, emphasizing the need for a relativistic version of quantum mechanics (QFT) to study interactions of light and matter.
  • Another participant asserts that modern particle physics is based on the Standard Model, which includes QED, QCD, and the electroweak force.
  • There is a claim that QFT is necessary for precision atomic physics, citing the Lamb shift calculation as a historical example, and suggesting that undergraduate quantum mechanics is insufficient for such precision.

Areas of Agreement / Disagreement

Participants present various perspectives on the relationships between the fields, with some agreeing on the hierarchical structure of atomic physics, particle physics, and QFT, while others provide differing interpretations of their interconnections. The discussion remains unresolved regarding the nuances of these distinctions.

Contextual Notes

Some limitations include potential missing assumptions about the definitions of each field and the implications of using QFT in precision atomic physics, as well as unresolved mathematical steps related to perturbation theory.

robertjford80
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For physics between QM and String Theory I've heard a lot of different names.

Quantum Electrodynamics seems to be the physics of the electron and the photon.

Quantum Chromodynamics seems to be the physics of quarks.

But High Energy/Nuclear/Particle Physics, Atomic physics, QFT, I don't know what the difference between them is. This forum has one category for HE/N/P physics and another for atomic physics so there has to be some difference.
 
Physics news on Phys.org
Atomic physics - study of atomic interactions
Nuclear physics - study of nuclear interactions
High energy/particle physics - study of fundamental particle interactions
QFT - the underlying mathematical theory of particle interactions, the particle world version of Newtons laws of motion. You take QFT and put various sorts of particles into it to create QED, QCD etc.
 
Atomic physics is the application of quantum mechanics to the atom, to study, as kurros says, atomic interactions and behavior.

In order to study the interactions of light and matter (QED), we need a relativistic version of quantum mechanics -- this is quantum field theory. So QED and QCD are physical theories based on QFT.

High energy physics is basically synonymous with particle physics, which is the study of the elementary particles and forces of nature. Modern particle physics is based on the Standard Model, which encompasses QED, QCD, and the theory describing the electroweak force.

So, really you have:

Atomic physics <----- Quantum mechanics
Particle physics (high energy physics) <------- QED, QCD, others <------- QFT
Nuclear physics <------- QCD, others <------- QFT, others
 
bapowell said:
So, really you have:

Atomic physics <----- Quantum mechanics
Particle physics (high energy physics) <------- QED, QCD, others <------- QFT
Nuclear physics <------- QCD, others <------- QFT, others

To be more precise, QFT is required to do precision atomic physics (the most obvious and historically first example is the Lamb shift calculation). Quantum mechanics as taught in undergraduate physics classes is not sufficient to do precision atomic physics (for example second order perturbation theory of most interactions gives infinite results).
 

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