Big Bang Critics

I think this comes back to cavedivers distinction between fermionic mass and bosonic mass. Photons have no rest mass (which I assume means fermionic mass). They do however have momentum, which is related to mass, so I don't think it's true to say that they have no mass whatsoever.

What is it that you've read?Off the top of my head, photons travel at c. This demands that they have zero rest mass as long as the relativistic equations are correct (and I've not heard of any evidence that contradicts them, but if there is I'll stand corrected). It's not possible for anything to travel at c if it doesn't have zero rest mass, from a relativistic point of view.I think I'll have to leave it to cavediver for a more in depth response though.

Are you aware of any observation that indicates that photons have a non-zero rest mass? Are you aware of any theoretical physics that argues that something with a non-zero rest mass can travel at c? Whether or not relativity is describing reality correctly depends on observations, not semantics.