Refractive Lensing?
Setterfield: Thanks for your questions. Let us take them in reverse order. You say that "The paper that inspired the video (linked) has an idea about red shift and blue shift can be caused by refraction. Can you comment on the physics/math? Does the mechanism actually work? Wouldn't wavelengths of light revert back to normal when the light returns to a medium with the same index of refraction?" Examination of the paper involved shows that the author is claiming that redshifts and blueshifts are caused by the changing speed of light in the medium of varying density around the object. He has worked on the basis of a constant frequency and so the color (wavelength) must change as lightspeed changes in the medium. However, using that approach does have the problem you pointed out, namely that once light came out of that particular medium, the color would revert back to normal. So it is not a valid explanation of red or blue-shifts of light from distant stars or galaxies. The other question you asked reads as follows: "Have you seen the latest post from the electric universe people? It claims that the blue colour of Einstein rings is evidence of chromatic aberration, which is characteristic of refractive lensing but not gravitational lensing. Do you agree? The idea of refractive lensing sounds similar to your idea of higher densities of virtual particle pairs causing light to bend around the sun." This is an entirely different problem. The claim that the blue color of the Einstein ring is due to chromatic aberration is only part of the problem. The other difficulty is to get an image or images of the object being "lensed" that may or may not be distorted. The only earthly equivalent to this that I can think of is the halo around the sun which incorporates sundogs. Conditions that allow this phenomenon are quite rare, and I would have thought that, astronomically, they would be even rarer. Yet this lensing seems to be a fairly common phenomenon astronomically. So I do not think that that is the whole solution. Instead, it is true that a strong gravitational field will have a very high concentration of virtual particle pairs around such an object, whether it be a very dense star, or a galaxy or a cluster of galaxies. As you say, this concentration of virtual particle pairs will bend light to produce lensed images and rings under appropriate conditions. So your speculation is correct. However, there is also another possibility different from both of the above, yet including some aspects of each. Galaxies and galaxy clusters are immersed in plasma filaments out of which they were formed. If we look down the long axis of such a filament, it is easily possible for a ring to form around the central object (whether it is a galaxy or cluster of galaxies). The effect would require that a bright enough object was illuminating the plasma filament down its long axis from behind. It would then be possible for this illuminating source to be lensed by this arrangement. I hope these options allow you to work though the possibilities that exist.
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