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

What is mean by an elementary particle ?

  1. Jan 24, 2007 #1
    What is mean by an "elementary particle"?

    I have always been intriguing about the definition of an "elementary paticle". Can we actually "define" a photon as a wave function $\psi(r,t)$ solution of the Maxwell Equation and "define" an electron as a wave function solution of the Klein-Gordan equation and so on?:confused:
    How about the "definition" of photons and neutrons and the others? :confused:
  2. jcsd
  3. Jan 24, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper

    Applying KG equation to the electron leads to erroneous results, as the KG equation is valid only for a field associated to a spin 0 particle.
    There's no universal definition to an "elementary particle". I like the one which involves the covering group of the Poicare' group and its irreducible representations.
  4. Jan 24, 2007 #3
    So, how about Quantum Field Theory which tells us particles can be divided into Ferminions and Bosons. Should we actually take a wave function $\psi(r,t)$ as a particle for different $(r,t)$? There must be a precise meaning before we work out QFT:rofl:
  5. Jan 25, 2007 #4

    Gib Z

    User Avatar
    Homework Helper

    No Universal Definition to elementary particle? I must have learned physics differently because I always thought that an elementary particle was one which has no inner-substructure. A proton is made up of quarks, so it isn't elementary. An electron is a lepton, made up of nothing else, so it is elementary.

    Btw: On PF you use [ tex ] and [ /tex ] tags after our math code (without the spaces).

    [tex]\psi (r,t)[/tex]
    Last edited: Jan 25, 2007
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook