This problem comes up because we have not yet admitted that we know just exactly what is mass. We have it well established in our equations and we can use the equations to solve problems every day. But for some reason we just don't admit that we know exactly what mass is. Well, we do know.

**Mass is electromagnetic change.** M = hv / c

^{2}.

It is the rate of change of electromagnetic fields in a local area that give us the measure of the amount of mass in that local area. When the amount is enough to give us atoms and molecules we need to use a different magnitude of measure but we know at the most elemental level it is still the change that produces the effect.

So, when we admit that we know that

**mass is electromagnetic change** we see that light does not have mass.

**Light is mass.** And not only is light mass, but light is the only kind of mass that there is.

These are my speculations; don't take these to class.

Just use this notion in your quest to understand how nature works.