Elpaw is right on this one. Rest Mass is constant.
Look to be honest... We can carry on about this for ages... I do not mind... But it is only fair, in my opinion, to say that yes light, in general, does have mass.
I think light has mass also. But the rest mass is different from the mass travelling at 999ms^-1. That's all i'm trying to say.
I think light must have mass because it has momentum.
Ponder about this will you...
m_0 is the rest mass
light does not have a rest mass
it is massless
however it has a momentum
may be hard to swallow but it's true.
Oh come on World... Do you not remember Einstein trying to fool the world with his "Cosmological" constant!?
But if light have no rest mass, how can mass increase at c when there's no mass in the first place?
This is getting to be another quack science thread. Why on earth do we have to waste out time talking about very old problems. The concept of light having momentum has been around since Maxwell's time, just look at his equations, they state that electromagnetic waves have momentum.
Yes but then is that not because all of E-M waves are made out of photons... This will just keep going around in circles...
No, it isn't because light is made of photons. The momentum of light can be derived using purely classical physics.
Sorry to say this MRLX69, but there isn't much here to debate. There is only stuff that you can learn. I can teach you the modern ideas about light, that they have no rest mass but momentum, I could even show you how to classically derive the momentum of an electromagnetic wave. But you cannot really debate it, as it is all stuff that has been figured out a long time ago.