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

Magnetic field is made of photons?

  1. Oct 23, 2006 #1


    User Avatar
    Gold Member

    i've been researching photons and i discovered on
    http://http://van.physics.uiuc.edu/qa/listing.php?id=414" [Broken]
    http://en.wikipedia.org/wiki/Photon" [Broken]

    both resources state that all mangetic fields are made of photons. soooooo, this brings up a lot of questions... first, why (when im in the presence of a mangetic field) dont i see light? (because light is mad of photons):cry:
    im sure if i get a simple understanding of this concept, it will probably rule out most of my questions, so i'll wait for a reply to continue.

    SO WHAT ARE PHOTONS MADE OF? -obviously they're charged (hence mangetic fields)
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Oct 27, 2006 #2
    Since it doesn't look like the lost replies that were made to this question will be coming back, I will answer it again.

    Magnetic fields are indeed made of photons. The reason that you don't see them is simply that your eyes are not sensitive enough. Electric fields are also made of photons, but you don't see tham either. You also don't see infra-red or ultra-violet radiation, because your eyes are only sensitive to very specific photon energies.
  4. Oct 27, 2006 #3
    And photons are fundamental units of energy so they are not made of anything else.
  5. Oct 27, 2006 #4

    Meir Achuz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    "both resources state that all mangetic fields are made of photons"

    I couldn't get to the first website. The Wikipedia was confusing as usual, but I didn't see that it said "all magnetic fields are made of photons".
    A static magnetic field is not made of photons. EM waves are quantized in packets called photons.
  6. Oct 27, 2006 #5


    User Avatar
    Gold Member

    thank you,
    i have a better understanding of photons now.
    so photons arent really particles (no mass) since they're energy. energy that apparently takes form of light, and simply energy.
    so photons are basically energy. there are more than one type of photon (light, mangetics. .... etc.....)

    but if these photons that make up (most) mangetic fields, are in a frequency/energy frequency -such as frequencys of light-
    what frequency are these in? there if they're not gamma, UV, x-ray, IF, visible light.
    what are they? do we know??
  7. Oct 28, 2006 #6
    the force exchange from a magnetic feild to something else is via photons,
  8. Oct 29, 2006 #7
    No tayleron, photons are particles (see the photoelectrc effect), energy is not light (although photons (light) have energy), and photons are more than just energy (they have other quantum numbers). Finally the photons in light and the photons in magnetism are the same thing - just with different energies.
  9. Nov 6, 2006 #8
    so photons are the force carriers for the electric and magnetic fields in the standard model? i thought it was something else?
  10. Nov 6, 2006 #9
  11. Nov 7, 2006 #10


    User Avatar
    Gold Member

    thanks severian
    i get the basic idea
  12. Nov 12, 2006 #11
    Does this mean that we can think of a magnetic and/or a electric feild as a standing wave of photons, much like a river?
  13. Nov 15, 2006 #12
    Could you think of a magnetic field as being length contracted, because the photons are in a closed loop, and time contracted because they appears as a standing wave having no relative movement, instead of an expanding wave with relative movement. Keeping in mind they always travel at c relative.
  14. Nov 17, 2006 #13


    User Avatar
    Gold Member

    that makes sence
  15. Nov 22, 2006 #14


    User Avatar
    Science Advisor

    Photons, as they are usualy defined, are associated with electromagnetic fields in the absence of sources (charged currents). So a better defined question could be: Do Maxwell equations without the sources admit purely electric and purely magnetic fields? If the answer is no, then there is no photon state that corresponds to a purely electric or purely magnetic field.
    Last edited: Nov 22, 2006
  16. Dec 15, 2006 #15
    If Photons are light waves and you’re able you reflect them with a mirror, and some are saying magnetic waves are virtual photons so can you reflect magnetic waves.

    And how could you reflect a magnetic wave “flux”, is it possible, a mirror will probably not work.
  17. Dec 15, 2006 #16


    User Avatar
    Gold Member

    Now *I'm* confused. Electric fields and magnetic fields are made of photons? (What an embarrassing gap in my knowledge...) What frequency are they?
  18. Dec 15, 2006 #17
    OK, this is gonna be a long one...

    First question, you say you have been researching photons. What exactly does that mean ? Also, when doing research you should NOT be using public libraries like Wikipedia.

    Secondly, i am sure you know that photons are defined as pieces of energy. Hence, the basis in which the "live" is the energy base. Photons are NOT point particles but energy-particles. It is very important to realize that. Knowing this, and knowing how E/M field are defined, you should already see that photons do NOT make up E/M fields.

    Thirdly, the theory that describes photons and their relations to E/M fields is QED. In QED we learn that photons are the force carriers of the EM interaction. This means that photons are the particles that mediate the electrical and magnetic interactions. In QED, you can also study (very important to know btw) how photons arise due to the vibration of quantum fields. Think of a mattress on which you jump in one place. The surface of the mattress vibrates and due to this vibration, there is energy coming free from the mattress (ie the vibrational energy).

    If you replace YOU by AN ELECTRON and the mattress by the quantumfield and you take into account that energy is the same as mass (E=mc^2) you can see how the vibration of a quantumfield can mimic a certain particle with mass m and momentum p.

    This is how photons arise in QED. Ofcourse photons do not have restmass m but still the principle of vibrating fields versus particles remains the same. How QED deals with the zero restmass of photons is a more complicated story. More specifically, the quantumfield in the photon case is the 4-vector potential A.

    One can actually rewrite the Maxwell equations with this A potential in such a way that they respect all necessary symmetries that need to be respcted (i know, this may sound a bit vaque but i don't know what level you are on so let me know). From this A potential one can also calculate the E and B fields.

    Finally, photons are NOT the constituent particles of EM fields, photons describe the interactions between electric charges (which exhibit an electric field) or/and magnetic dipoles, quadrupoles (which have an associated magnetic field) etc etc ...

    In QED photons arise thanks to the vibrating A field (think of it as the A mattress :wink:). In other words, photons arise thanks to the quantisation of the waves in the A field. This A field is closely related to the E and B fields, so being a bit less accurate, you could also say that photons correspond to the quantisized energy of vibrating E and B fields.

    Last edited by a moderator: May 2, 2017
  19. Dec 15, 2006 #18
    Any frequency you like. Any field of photons is an electric field or magnetic field. Which of the two it is is dependant on your frame of reference, since a Lorentz boost will transform one into the other.

    I have no idea what Marlon is smoking... :tongue2:

    Think of it this way. A charged particle moves in an electric or magnetic field. Where does it get the momentum from? It gets it from absorbing a (perhaps virtual) photon.
  20. Dec 16, 2006 #19

    Marlon is smoking QED

    Oohh, so electrons are absorbing photons now ? I would suggest you study which processes allow for this to happen in high energy physics. You might be surprised.

    When describing charged particles in fields (Maxwell, Lorentz force) we don't use photons. All is classical field theory here.

    Indeed, in QED, charged particles interact through the exchange of virtual photons. But again, such photons do NOT MAKE UP and E/B field. In their original definition E and B are classical fields NOT quantumfields.

    Also, as i told in my previous post. In field theory, particles arise through vibrations of quantumfields.
    Photons are the quanta of the electromagnetic field (expressed by the A potential). You may also
    think of it as the energy contained in the electric and magnetic fields which make up the
    light wave. This duality is a basic part of quantum theory.

    Clearly, one cannot just say...ohhh we have particles that make up a field...This is NOT WHAT QED teaches us.

    Last edited: Dec 16, 2006
  21. Dec 16, 2006 #20
    Guy’s I previously asked this question but it’s in the first page and nobody probably going to turn one page back.

    Will I be able to reflect magnetic waves from a permanent magnet just like you should reflect light with a mirror?
    Because some say magnetic waves are virtual photons or something and light are just photons.

    And to my understanding the word photo means something that you can see with your eyes and virtual also has to do with the word photo?? So I don’t know if magnetic wave are virtual photons and a normal light bulb is also a photon generator because photons are light. Does someone have a clear answer for this confused understanding from me or maybe some other people to
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook