Hi Jesus Freak!
Let me address your last link first:
This link talks about the discovery of evidence that the fine structure constant has changed over time. The article is from 2-1/2 years ago, and other teams of scientists have been unable to replicate these measurements. The original team that made the announcement has conceded that they were probably mistaken.
Even if the measurements had been successfully replicated and confirmed, the effect on the speed of light would have been far, far less than required to be consistent with the claims in your other three links.
Your other three links consider the possibiltity that c has been slowing over time, and offer as evidence past measurements of higher speed than today:
So your evidence that c has slowed down is past measurements of c. Some replies to you have suggested that the measurements were chosen to show a decreasing trend, that other measurement made in the past were slower than the currently accepted value of c, but they've offered no evidence of this, and I think they should do so or drop the claim.
Recall that the scientists described in your last link thought they had found that the fine structure constant had changed over time, and that they thought this because of measurements they'd made of light arriving from distant stars. In other words, we can draw conclusions about the speed of light by measuring the light from stars. Your second link cites these measurements:
1657: Roemer 307,600. +/- 5400 km/sec
1875: Harvard 299,921. +/- 13 km/sec
1983: NBS (laser method): 299,792.4358 +/- 0.0003 km/sec
1657 was 348 years ago. When we look at stars approximately 348 light years away, which means the light was produced in 1657, there is no indication that this light ever traveled faster, and especially not 7000 km/sec faster, which is a huge amount.
1875 was 130 years ago. When we look at stars approximately 130 light years away, there is no evidence it ever traveled 129 km/sec faster.
One very interesting question to ask is what would light that had traveled faster in the past look like. In other words, what evidence should we look for in the light arriving from distant stars that would tell has it had once traveled faster than c. Would the spectrum be different? Wouldn't a faster c imply that the interaction of physical laws would be different, so wouldn't the differences actually be spectacular and dramatic? You see, changing physical laws, which is what your links propose, has many more fundamental implications than a simple expansion of space, which is what scientists currently believe. While it is perhaps possible that changing physical laws could give an appearance identical to an expanding and accelerating universe, I don't think anyone has yet produced an explanation for how this could be so.
I'd like to conclude by revisiting the measurements of the speed of light and comparing them to measurements of the charge of the electron. The initial measurements of the charge of the electron were performed by Robert Millikan in his famous oil drop experiment. His initial value was too large, I think by some 10's of percent. Other scientists replicated his experiments and reported their results, each reporting successively smaller and smaller values, until finally they arrived at a value fairly close to today's agreed upon value. While some of the causes of the iniital too-high measurements were due to inherent bias resulting from the equipment and the nature of the experiment, that doesn't account for all of it. A good part of it was the influence of the desire of scientists to be as consistent as possible with prior results. Scientists aren't perfect - last time I checked, they're human, just like you and me.
--Percy