The speed of electromagnetic waves in a vacuum is what 186,000 miles per
second, right? And in a conductor it is a large fraction of c, let’s
say it’s 80% of c or about 150,000 miles per second. That’s close to c,
and that’s why I refer to it as "near light speed." Follow?
Well, the funny thing here is that you claim that the signal is in photon form. If so, its going at the speed of light 'cause that's how fast photons go on account of quantum. And if that's so, what can be inferred from that is all you have to do is put the signal through a cable and you can slow it down (on account of the dielectric and quantum). If that is so, it is further inferred that all you need is enough dielectric and you could get a person pedaling a bicycle to go at the speed of light. Then of course you could shed the dielectric and presto! the bicycle made it to Mars in only 30 minutes.
Of course, none of this is really possible, because signals **don't** travel in cables in the form of photons (which is of course ridiculous) and also not because of quantum :)! Of course I've been having some fun with this!