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

Timon and Pumba on photons

  1. Aug 7, 2003 #1


    User Avatar

    Timon, Timon, I wonder howcome photons have no mass at rest and yet mass is their only property?
    Pumba, Pumba, you wonder - I know. There are no photons at rest!
    ha, ha, ha...ain't it funny?
  2. jcsd
  3. Aug 7, 2003 #2


    User Avatar
    Science Advisor
    Gold Member

    What do mean by that? Photons have energy, travel at the speed of light, have spin 1, and other properties.
  4. Aug 8, 2003 #3


    User Avatar

    it is because...

    the energy of the photon is E=mcc
    the momentum p=mc
    if m=0 (there is no m) then
    E=0;p=0... too(there is no E,p...).
  5. Aug 14, 2003 #4
    Re: it is because...

    Doesn't work that way.


    If mass is 0, than energy is equal to momentum times c.

    Think relativistically!
    Last edited by a moderator: Aug 14, 2003
  6. Aug 18, 2003 #5


    User Avatar

    Re: Re: it is because...

    Ok, how much is the momentum then?
  7. Aug 18, 2003 #6
    Obviously then the photon must have mass ,right ? And if we follow this statement through to its conclusion it means that energy must have mass ?
  8. Aug 18, 2003 #7
    Why must a photon has mass? Look at the equations again. Energy approximately equates to momentum with a zero rest mass particle (mass disappears at c/c in the equation). So its MOMENTUM that relates to energy with the photon, not mass.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Timon and Pumba on photons
  1. What is photon emission (Replies: 24)

  2. Photon ? (Replies: 2)