CDK refers to the decay of "c." It cannot do what it set out to do with a speed of light that used to be slower and is speeding up. You see, what it set out to do is explain why we "think" we see objects millions or billions of years old. (They are apparently millions, even billions of light-years away. There would not have been time in a young universe for light from them to reach us in any manner unless light used to be much, much faster and not long ago.) If light had slowed down dramatically very recently, that should help cram quasars into a 6000 year old universe. If light is speeding up, the problem only gets worse.
Again, if light-speed is really changing, according to this study it has speeded up a tiny fraction in 2 billion years.
Like , I said in my follow up "Oops, I misread and went another direction. That's an easy mistake to make since scientists around the world have been debating the other direction for over ten years. And frankly this would be the first bit of opposing, as in the opposite direction, theorizing that I have seen. I'll have to wait on peer review for this one. And like I said, the momentum is sliding towards cdk not "c speed up."