On a video on Youtube, I commented how a PBS Space Time episode helped me understand the speed of light by calling it the speed of causality. In response, I received the following comment:
"Let's check your learning: Why can we consider light speed to be the speed of causality?"
My answer to this was:
"If I understand correctly, it's because it is the fastest speed at which information can travel. So, it is the fastest speed at which someTHING can interact with another THING. Is that right?"
To which they responded:
"Well it is certainly true, but it's missing the cause/mechanism. Its the speed at which the electric and magnetic fields interact. A photon is the result of a changing magnetic field inducing a changing electric field, and a changing electric field induces a changing magnetic field. That interaction of the permittivity and permeability of "free space" is the speed at which the field interact and that is c, or the speed of light."
This didn't sit right, because gluons travel at c as well, and as far as I knew did not require the electromagnetic force. So, it would seem to me that the speed of photons transcends merely the electromagnetic force because it applies to gluons as well. So, I responded back:
"Hmmm. That may be partially true, but would fail to explain the gluon, which also moves at the speed of light and, as far as I know, carries the strong force. So causation is the same speed for the strong field too."
And they responded thus:
"That is because gluons interact with virtual photons. What is the strong field without the electric and magentic [sic] fields, what is a proton without electromagnetism? You are right to point out other forces, but they all interact at c for the same reason."
Now, the first thing I find confusing is when they say that gluons interact with virtual photons. This to me sounds like they are saying that photons carry the strong force between quarks and gluons, but I always thought gluons were the virtual particles moving the strong force between quarks and gluons. Then the ending sentence has me with more questions.
They say, "They all interact at c for the same reason." And that reason, I can presume is the reason given before: "Its the speed at which the electric and magnetic fields interact." But how do we know that c is derived from the speed at which electromagnetic fields can interact and not based on how strong nuclear fields can interact.
I lack the knowledge to assess these claims. Is what they are saying making sense? I would ask the commenter questions about what he has said, but I have zero faith in the reliability of a random Youtuber who comes off a tad smug. If you don't have proper stack credentials, your words are meaningless on questions like this. I would appreciate any help you could provide.