Speed of light has changed

Claim

The speed of light was faster in the past, so objects millions of light-years away are much younger than millions of years.

Norman, Trevor and Barry Setterfield. 1987. The Atomic Constants, Light, and Time. Flinders University of South Australia, School of Mathematical Sciences, Technical Report. [1]

Setterfield's argument does not hold water. There are differences between historical measurements, but they are within the bounds of accuracy - the first measurements were very inaccurate, then they became more and more accurate. Setterfield blows the differences up by not only extrapolating them into the past without justification, but also using a curve cooked specially to point at an age Setterfield wanted to get. A constant speed of light is well within the error bars.
Even if the speed of light did decrease since creation, then that would only place Supernova 1987A even further back in time and so this would not imply a young universe.[2]
This is accepted by many Creationist groups as an invalid argument, and has not been used in some time.
If the speed of light were faster in the past, that would make the universe older, not younger than it is currently believed to be. That's why this argument is generally used by those who believe in "steady state theory", that the universe has always existed, forever and ever. They, also, are crackpots.
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