Helen
"please read what you want on the Discussions page and then feel free to ask specific questions. The points you mentioned before here are all dealt with there. Please read first and then come back with some specific objections or questions. He has a response to the idea of 'time slowdown' there. Thank you."
I went back and read much of the material again. There were some things marked "New" I had not seen before. Admittedly, if the subheading did not appear promising, I mostly scanned looking for relevent material. What I found mostly convinced me that my question is on the right track. I also found one glaring mistake.*
There is a lot of talk about the different speed that things governed by atomic processes would have had. The most relevent question was answered "Since many atomic processes are faster proportional to c, but the slow motion effect at the point of reception is also operating, the combined overall result is that everything seems to proceed at the same unchanged pace ... Therefore no astronomical evidence for a slow motion effect in atomic processes would be expected."
There is a good discussion of why under the discussion about SN1987A. As I said earlier, this slowdown effect is a critical part of what Barry has to say. But let's look as his example of a supernova occuring when the speed of light was 10 times its current value. The light curve of a supernova is mostly dependent on the decay of certain isotopes. Now the rate of decay would be ten times higher but the higher speed of light would cause a ten fold slowdown in how the process appears to run to an observer. Therefore, the light curve would look normal. But a process that was not atomic would not be affected by the changing speed of light and would therefore have been running at its normal speed. It would be subject to the same tenfold slowdown and would appear to an observer to be operating ten times too slowly. This is why I focus on non-atomic processes.
Now he also tries to say that "First of all, pulsars are not all that distant, the furthest that we can detect are in small satellite galaxies of our own Milky Way system. Second, because the curve of lightspeed is very flat at those distances compared with the very steep climb closer to the origin, the change in lightspeed is small. This means that any pulsar slowdown rate originating with the changing speed of light is also small." I assume that this logic can be applied to any objects within the Milky Way or its nearby galaxies.
Here is the problem. The curve may be flat compared to the rest of the curve, but there still must have been significant change. Think of it this way. Our galaxy is about 100,000 light years across. For light to have traveled that distance in 6000 years, the average speed must have been at least (100000 / 6000 = 16.7) 17 times as fast as it is now. Since the speed is decaying, the initial speed must have been much, much more than 17 times the current value to get that average value. (Your charts also show meausurable change in the speed of light in the last few hundred years which should have produced observable effects in objects within a few hundred light years.) Let's use 100 for arguments sake. I think we should be able to tell that something in our galaxy is running 100 times more slowly than it should.
Again, I present the example of an eclipsing binary. We can measure their distance apart. We can use spectroscopy to determine their spectral type and therefore their masses. The distance between them and their masses leads to a direct calculation of their orbital period. Surely we should be able to tell that the period is off by a few percent and certainly that they are of by several factors or even orders of magnitude. All my reading of Barry's work says this is an obvious prediction. So why is it not seen? This a purely orbital clock and should be completely unaffected by slowing light except for the slowdown effect to the observer. The effect should be seen in every object of this type, the discrepancy should be able to be predicted in advance, and the discrepancy should increase with increasing distance in a predetermined way. Now, what have I missed?
Now specifically concerning pulsars, since I mentioned that, he attempts to get out of it by saying "The third point is that the mechanism that produces the pulses is in dispute as some theories link the pulses with magnetic effects separate from the star itself, so that the spin rate of the host star may not be involved. Until this mechanism is finally determined, the final word about the pulses and the effects of lightspeed cannot be given." Now, unless the pulse is a purely atomic process, there should be some changes in period involving cDK. Though I will grant that it could be possible the change in spin rate could swamp the changing effect from changing light speed. On the other hand, if the pulse is not a purely atomic process, the distant pulsars should still be seen going much more slowly than the nearby ones. This is not seen. In fact, I thought the fastest known pulsar was in the LMC.
Just rambling on, there should be all sorts of weird effects due to process that are mixed atomic and non-atomic. Think of a variable star, for example. Obviously, there are going to be atomic processes involved, but many other processes will also be involved. Rather than the predicability we see in ceratin types of variable stars, there should be really strange effects observed as the atomic and non-atomic processes interact to cause the periodic variability. There seems to be a lot of different types of processes for which this would be true.
*"Nevertheless, which ever option is adopted, the main effect of dropping values of c on quasars is that as c decays, the diameter of the black hole powering the quasar will progressively increase. This will allow progressive engulfment of material from the region surrounding the black hole and so should feed their axial jets of ejected matter. This is the key prediction from the cDK model on that matter."
First let's look at where the energy of a quasar comes from. The great gravity of the supermassive black hole causes material to fall towards it. As the matter falls towards the black hole, the pull of gravity will increase the speed of the material and flatten it into a flat disk, an accretion disk. The close to the black hole, the faster the material moves. This difference in velocity causes friction between adjacent areas. Tremendous friction in the case of a quasar that superheats the material and releases large quantities of radiation. This radiation is the energy we see coming from the quasar. As the material nears the black hole, it passes what is known as the event horizon. This is the point where the escape velocity from the gravitational well of the black hole equals the speed of light. Once inside this limit, neither the material nor the radiation it is emitting can escape the black hole. Though strangely, nothing special happens at the event horizon to the matter. Note that this is a non-atomic process. Just gravity.
So, with a higher speed of light the event horizon would have been closer to the black hole. This is because you would have to be deeper into the gravity well of the black hole for the escape velocity to be equal to the higher velocity. As light slowed, it is the event horizon that would expand. I have seen him mention in other places the Schwarzschild radius when discussing this topic which gives assurances that he is talking about the event horizon.
Now an expanding event horizon would gobble up no more material for the black hole. It does not affect the gravity of the system. And the material is being pulled in solely by gravity. The only effect of an expanding event horizon would be a slight dimming of the quasar as part of the accretion disk emitting the radiation is placed within the region from which its radiation cannot escape. This may not even be true as the increased energy from the inner accretion disk may have been pushing material away from the rest of the accretion disk, slightly lessening the energy thus released. The overall effect of an expanding event horizon should be minimal. The "key prediction from the cDK model on that matter" seems to be incorrect.