# Photons in pair production

I know that they are always produced in pairs in order to conserve momentum, but the equation for momentum is mass x velocity. Aren't photons considered massless? Wouldn't their momentum always be 0 if their mass is 0? Why do they always have equal energies? And how would you calculate their momentum?
(edited 1 year ago)
Just google it - the momentum of a photon is based on wavelength.
https://courses.lumenlearning.com/physics/chapter/29-4-photon-momentum/
Original post by cassielle
I know that they are always produced in pairs in order to conserve momentum, but the equation for momentum is mass x velocity. Aren't photons considered massless? Wouldn't their momentum always be 0 if their mass is 0? Why do they always have equal energies? And how would you calculate their momentum?

Have you covered the de Broglie wavelength of particles?
Original post by Sinnoh
Have you covered the de Broglie wavelength of particles?

Yes, does that have something to do with it?
Original post by cassielle
Yes, does that have something to do with it?

It means that you can calculate momentum when all you know is wavelength. So the idea of momentum doesn't have to be linked so much to the idea of mass.
(edited 1 year ago)