That, or their mass would be decreased by the square of C's increase, which would prevent distant stars and galaxies from cohering together. Yet there they are, so we know that isn't happening.
I used to be enamoured of the possibility of C-decay making the universe younger than thought, until someone pointed out the very obvious rammifications of that in light of E=MC^2. It simply doesn't work, even if we didn't have the ability to directly measure the energy--and therefore the speed--of light at the moment it left those distant stars and galaxies . . . and we do. Look up hyperfine split lines.
Just as much to the point, YEC might be required for a literal understanding of the English translation of Genesis, but it is not for the original Hebrew. The more I have learned about the Hebrew words used, what they mean, how they fit together, how they are conjugated, and how the language just works differently than English (lacking much in the way of tenses, for example), the more comfortable I have become with the reality of an old universe.
Shalom.
This assumes the light we see today represents the energy at the light's origin. If the the speed changes it would assume that the energy it represents would change with it along it's travels (if all laws decay together). Whether the origin had more or less energy than it does today, assuming all laws of physics are changing as "time" and "space" change, then would the results not remain consistent (red shift)?
In deep space we measure mass and energy based on gravity (and how light is affected as it travels). If the energy of the light that has been traveling for billions of years decayed at the same rate as the speed, and at the same rate of the origin's mass and energy, would the red shift not show what we see today? Remember, we assume gravity as a constant function of mass and space throughout the universe too. Yet we do not understand the source/force that causes magnetic attraction associated with mass. If the laws of gravity have evolved along with energy, speed of light and mass traveling in the universe, then our snapshot is accurate but not representative of Universal Laws of Physics at the moment of the Big Bang.
For that matter, what if gravity as a function of mass is different in every galaxy? We can only assume the consistencies beyond a certain distance and speed as we rely on light and use that data based on established Laws of Physics. The very mass of our own planet is established based on it's own gravity and it's consistency with that of our moon and surrounding planets. These functions are observable in our own solar system and establish our understanding of the mass of our sun and our neighboring planets. But Satellites verify the size of our planet based on the known distance of our moon based on bouncing lasers off of solid objects. We can't bounce lasers off of distant stars (and galaxies) so we rely on the light they sent to us billions of years ago.
Again, I assume you to be of superior knowledge on this subject, but am fascinated with Science's inability to reconcile our Laws of Physics with what is theorized as our Universe's origin. I recall learning some Physicists frustrated conclusion that the Physics to support the Big Bang Theory do not fit the Laws established today. As a neophyte, this has always begged the question for me, "Why do we assume the laws are constant over billions of years?" Couple that with recent revelations that Quantum Physics is finding particles that don't obey our established laws and I say it is fair to explore taboo ideas that go against the established Laws of Physics. After all, is that not what science is?
I've had this discussion before (likely with less knowledgeable subjects) where someone finally said, ALL scientists agree..... CONSENSUS? LOL Ultimately, I giggle at the ambitious and sometimes presumptuous human effort to figure out how God did it. But I admit to being curious myself and I think God programmed us to be this way.
Thank you for your effort, I am learning a lot.