If the speed of light has slowed down, that will affect our measurements of the age of the universe, and the universe might actually be much younger than we thought.  We urge caution in any reading of the following links.
 

We believe if the speed of light has decayed, that would be one of the greatest scientific discoveries of all time.   It would support the belief the Earth is young and thus the genealogy of Christ in Luke Chapter 3 in the Bible is correct.  Thus all the laws of physics would point to Christ's genealogy, and all the laws of physics and every atom point to Him.

Caution is urged in reading the following links, but many of us are cautiously optimistic.
 
 

Speed of Light Decay (world net magazine)
 

Walter Brown PhD, MIT
 

Speed of Light Decay (CBS)
 

Historic Measurements

Setterfield Cosmology (HIGHLY TECHNICAL)