Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What's the difference between QFT and Atomic physics

  1. May 22, 2012 #1
    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.
  2. jcsd
  3. May 23, 2012 #2
    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.
  4. May 23, 2012 #3


    User Avatar
    Science Advisor

    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
  5. Jun 4, 2012 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    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).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook