This theory fascinates me and I would love for it to either be debunked, or to find others to discuss it with. Essentially the idea behind the varying speed of light is that the speed of light as a constant can be manipulated by warps in spacetime, which is to me a logical explanation to the cosmic inflation we see in the pictures of the universe we have been able to capture.
Cosmic inflation is, as far as I understand it myself, a phenomena whereby the big bang had asymmetrical expansion rates. If you imagine an explosion at a fixed point in the vaccum of space it is easy to picture a perfectly spherical explosion, but what we observe in the cosmic microwave backround is that some light is moving faster than we think it can.
So the idea behind the varying speed of light as I understand it, is to think of a section of space like we might think of a wire in electro physics, a big bang explosion is sending light energy outwards, and just like in a wire, the more light is concentrated in a given volume of space, the slower the speed of light becomes. Andreas Albreicht explained in a documentary that, closer to the origins of our universe, energy was closer together, more collisions happened, and light travelled less quickly and therefore a less distance over the same period of time as it would have nowadays, when things are more spread apart. Things like gravity waves are created by massive stellar bodies like stars and black holes and can compress space or time.
Then there’s the article on wikipedia, https://en.wikipedia.org/wiki/Variable_speed_of_light
The thing that really captivates my attention on this issue is that, my intuition tells me that variations in the speed of light would change the ‘age’ of the universe. If light needed more time to travel some of the distance than another, then it would make sense to see it with less energy on the cosmic microwave backround image, because to that light, traveling the same distance took more time and therefore more energy.
Obviously, this phenomenon would have been short lived, and by the time our solar system was formed the speed of light was constant. It would have been the amount of time very early in the big bang, and pondering on that has been a great source of joy for me. Has this theory been supported or contested? I should probably look it up on google scholar next! Thought I would share though.