[oldandtired]

The first thing to point out here is that the

> the speed of light

is not

> 299,798,452 m/s

It is quite inaccurate to say this. The correct way to phrase this is that the speed of light is 1/sqrt(permeability * permittivity) of the medium through which the light is traveling.

For a perfect vacuum, these two properties of that vacuum give a result as specified above. For other specified medium, you will get a different value, which could be greater than or less than the above figure.

Little technicalities matter in such cases, as it opens up the discussion. Part of that discussion is that solar space or interstellar space or intergalactic space will have distributions of matter that can alter what the speed of light is away from the assumed perfect vacuum speed of light.

Simple assumptions such as perfect vacuum are quite likely to affect how accurate our models of the universe are. The problem for us is that we are here and not out there making actual on location measurements of the permittivity and permeability of the relevant regions. The assumptions made in our models can come back and bite us in the long term.

Now as for the models we use currently for proton and neutron structure, there are assumptions here that could well be misleading us even though our models appear to work. There are alternate models available (since at least the early 20th century) which have, as far as I know, not been investigated with any detailed effort. Now, of course, it doesn't mean that these alternatives are actually viable, but we don't really know at this time.

[pnut]

Another important point is that other things besides light (for instance, gravitational influence) travel at the speed of light.

It's actually the speed of causality / information transfer.