- #1
Aaron121
- 15
- 1
In A.P. French's Special Relativity, the author said the following,
As I understand, photons are massless, so I don't think the last equation above applies to photons, but then, when deriving it, he used an equation proper to photons (##E=pc##).
So in which context is ##m=p/c## valid?
For photons we have
##E=pc##and
##m=E/c^{2}.##Combining these, we have
##m= p/c##
So in which context is ##m=p/c## valid?