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

Mass of the photon depends on the frequency?

  1. Dec 22, 2009 #1
    Mass of the photon depends on the frequency??

    Hi all,

    I'm 4th year electronics engineering student and so my question is curiosity.. We have taught that the photon has no mass, or its mass is zero. They even (the teachers and instructors) say that its mass is not negligible, but it is ZERO. This is for me not logical answer, it is a particle, then it must have a real mass even if this mass is 10^-99999999999Kg!

    We have the energy of the photon E=hv, and we have E=mc2

    E=E
    hv=mc2

    this means that m(photon)=hv/c2;
    h/c2 is constant and the only variable is the frequency or the wavelength

    This means that a photon with high frequency (which has higher energy) has more mass.

    The mass of the photon (at a certain frequency) times c2 gives us it's energy (it looks similar to the kinetic energy of a moving mass).

    A photon at rest or with no frequency does not exist, and therefore the rest mass is zero is only something theoretical...

    And according to my view about the mass of the photon, if one substitute some different values of an electromagnetic wave, he will get logical values for the mass.

    For example,
    7.36 x 10-51 is h/c2
    for a 1MHz frequency, the mass of the photon will be about 7.36 x 10-45 which is logical since it is much less than the mass of an electron.

    In dialectical materialism and as the science proved, the energy doesn't vanish. And here I mean by energy both m and E which are in unity. So if we considered the energy E to be a mass of photons (and for example, also phonon for heat energy..), the mass itself would be in unity and the energy becomes only a theoretical explanation of the mass energy particles.

    Awaiting for your views...

    Hazim
     
  2. jcsd
  3. Dec 22, 2009 #2
    Re: Mass of the photon depends on the frequency??

    No E is not equal to mc^2 in general, the most general formula is

    E^2 = (mc^2)^2 + (pc)^2

    where p is the momentum and m the rest mass.
     
  4. Dec 22, 2009 #3

    HallsofIvy

    User Avatar
    Science Advisor

    Re: Mass of the photon depends on the frequency??

    Then you have an incorrect idea of "particle". The physics definition of particle does not require that it have mass.

    More energy, yes. That does NOT imply "more mass"

     
  5. Dec 22, 2009 #4

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Re: Mass of the photon depends on the frequency??

    You are strongly advised to read an entry in our FAQ in the General Physics forum. You should also not make such speculation without paying attention to experimental evidence. For example, you will have a whale of a time trying to reconcile your assertion with this result: A.A. Abdo et al., Nature v.462, p.331 (2009).

    Zz.
     
  6. Dec 23, 2009 #5
    Re: Mass of the photon depends on the frequency??

    More mass imply more energy right? Considering the energy being a mass (quantum particles having mass as I said before) means that more energy imply more mass...
    I confess that I don't have a good awareness of quantum physics but this may be a start for me in this interesting field.
     
  7. Dec 23, 2009 #6

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Re: Mass of the photon depends on the frequency??

    This is patently false and incorrect. You wouldn't make such an erroneous statement had you done a little bit of "homework", such as reading the FAQ.

    Please make sure you review the PF Rules that you had already agreed to. It is one thing to want to learn about physics, which we encourage. It is another to not care about basic physics (especially when you've been given it) but continue to make speculatively and spectacularly wrong guess work. The latter is not permitted in this forum.

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