Bad if you want to claim the speed of light is the same in all mediums then you need to go join your buddies who say solar panels will drain the sun and kill all the plants.
There's no new physics here it's an established irrefutable fact that the speed of light depends on the medium it's traveling through.
The stars are moving and the earth is motionless, case closed.
Case not closed.
Speed of light is irrelevant.
Action of light traveling through a particular medium as opposed to some other medium is irrelevant.
The thing that rules is the action of light through the ether... or through space if you want to believe in space rather than the ether.
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Physics is flawed. It is flawed because basic math is flawed. For example, 1 + 1 never equals 2. Why not? Because there are no two things that are exactly the same. They are always at least a little different. Because of this, 1 + 1 will always equal 1 + 1... never 2.
When you consider this, the deeper you get into any form of physics, the greater will become the flaw. This is part of the reason why standard physics has more and greater holes in it as you apply greater math to describing that physics. Certainly the physics itself doesn't have any holes. It is the description of physics that produces understandings that are flaw, because the description is based on the flawed language of mathematics as it exists.
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When I say that "you can't," I don't mean that you are unable to make the attempt. But the thing that you are attempting to do is to take some pieces of a flawed description of physics, and apply them to a different description of physics to make a more accurate description of physics. If you don't apply quantum math to what you are doing, the odds are that your description will be more flawed than the one you are attempting to replace.
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Parallel universe theory suggests that there are as many as an infinite number of universes occupying the same space and time that ours occupies. Parallel universe theory never really got off the ground, because it requires the ether to make it work. The ether is the substance that the parallel universes are "made" out of.
We have mathematically (with our flawed math) described completely 6 or 8 dimensions. We have a good handle on another 6 or 8. Then there are 15 or so that we have some math for, but these are not seen at all clearly. Yet it is the dimensions that express the way the parallel universes exist in different "phases" that keep them separate while at the same time allowing them some interaction.
Let's say that some star out there somewhere, shoots out a photon of light. This photon makes it to earth and is observed. Yet the photon itself is a thing that has changed untold times over simply to "travel" the distances from the star to the earth. It is destroyed and recreated by interactions of the various universes according to dimensional laws (ether laws) that cannot be comprehended by space physics.
Flat earth is attempting to apply space physics to ether physics in some areas. It simply will not work. Flat earth ideas are just as flawed as current standard ideas.
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One + 1 does not = 2. Again, the reason is that there are no 2 1s that are the same. The closest that we can come to making 1 + 1 = 2 is found in quantum math, because it is the closest that we can come to finding two 1s that are the same. Where are these two extremely similar 1s? They are 1 and -1. The only difference between 1 and -1 is the "charge." Yet, with our math, 1 + -1 = 0.
The ancient peoples from the past, past that we formally calculate as, say, 14,000 years ago, recognized this. It is the reason their science was different than ours. It is the reason that their science was based on something more accurate. It is the reason that they were destroyed in a cataclysm that nearly destroyed the earth, because even THEIR math/science was flawed. We are heading the same direction as they, partially because our science, flat earth or round earth, is even more flawed than theirs.
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Flat earth and round earth are fun to play with. Play. But get down to life, as well.