Jim: ??Also I do not contend that any past theory is false or faulty. That is beyond the scope of my knowledge. If we all thought the same there would be little progress.?

Well, Jim, I am sure you got intellectual satisfaction from your work over the years on this issue. But are you not curious to see if your work matches reality? Sure, it answers some questions, but are you not curious if it also matches observed phenomena, phenomena upon there is little experimental doubt?

Jim: ?My contention is that light does have a density and can be expanded or compress in the same manner that a gas is compress, except we use mirrors and 'magnifing glasses' to do it instead of pumps.?

OK, this sounds reasonable. In fact, photons can be imagined as a gas, and as such there is a density of the gas (number of photons per unit volume). However, since this is not a very good description if you have photons of different frequencies (it would require you to work with partial pressures of rather odd types), one uses something called spectral energy density, defined as number of photons per unit volume and per unit frequency.
In this description, you don?t need mirrors, or magnifying glasses to compress or expand the gas, you can treat it thermodinamically, like any ideal gas, just with a special equation of state.

Jim:?Light leaving the sun is as dense as it will ever be and from that point onward is always less dense. This "density" will decline as the light moves througout the Solar System. This light, as I see it, can be compared to a gas being released from a container. It will continue to expand until it dissipates, much the same as light diminishes with distance.?

OK, let?s assume things are the way you say

Jim: ?We must always keep in mind that the expansion is spherical. The speed of light is in part a product of the density of the light and the rate of the expansion of light.?

Well, spherical symmetry aside, you need to define what you mean in the second sentence. Density is measured (in your case) in kg/m^3, while the expansion rate (which I don?t yet understand what you mean by that) should be in something/second. Now, if you want this product to be a speed, the something must have units of m^4/kg. Which doesn?t seem to make much sense.

So, what do you understand by density of light, and what do you understand by expansion rate of light? Please define them, units and all.

Jim: ?This, if correct, is a natural control of the potential speed at which the light will travel because the rate of expansion is means by which light speeds up.?

So what you are saying is that v=CdR, where v is the speed of light, C is a dimensional constant, d is the density, and R is the expansion rate. And you say that R controls v. OK, let?s assume that. But how did you come up with this equation?

Jim: ?This would mean that light in the vicinity of Earth is clocked at 186,281 miles per second while the expanded light at Jupiter will be less dense and capable of traveling faster.?

Well, keeping the analogy with the escaping gas, as distance increases, density decreases and rate of expansion also decreases, so light should slow down at Jupiter compared to Earth. How did you come up with the opposite?

Jim: ?The first hurdle here is to explain why we measure light returning to us from Jupiter at the same speed we measure light passing us here at Earth. I contend that the reflected light leaving Jupiter is traveling faster as it leaves but while it travels back to Earth it is slowed and slowly compressed along the way so as to meet us here at Earth traveling at our environment?s speed. This would apply to light originating from any source, including distant stars. This gives us a nice comfort zone and the conclusion that the light speed is fixed always.?

Well, your hurdle is just one issue. But your explanation has generated two other questions, that did not exist before. The first is what is the speed of light when light is emitted by a source. The second and an even more important one is this: according to your model, what is the maximum speed the light can ever attain?

But if your scenario with light travelling to Jupiter and back is true, this should be observable through the telemetry measurements I was talking about earlier. In these measurements, it does not matter what the speed of light is at the point of origin/return of the pulse. Suppose that value is known. These measurements can determine if the light has traveled along its path at constant speed or if the speed along the path has varied. Any variation of the speed along the path results in a time lag or a time advance, and such a thing has simply not been observed.

Jim: ?Example: Earth at 7926.6 miles diameter divided into the sun's circumference of 2,714,342.4 equals 342.45 and the square root of that is 18.5, the miles per second of the Earth?s orbital speed around the sun. You can do that same test with kilometers and get the same ratio result but we know 18.5 kilometers is meaningless in this workup.?

Jim, the calculation doesn?t make sense dimensionally, it only makes sense as maybe a mnemotechnic rule. Dividing miles by miles you get a dimensionless number, whose square root is also a dimensionless number, that coincidentally reproduces some number associated with Earth?s orbital velocity. This is all, there is no hidden meaning. I can only hope that you did not fell into the trap of ?pyramidology? (you know, finding the golden ratio/section in the Khufu pyramid at Gizeh, Charles Piazzi Smith, etc.)