jcsd said:
This is precisely how it seems to be and my beef is that 5 coordinates does not necessarily mean 5 dimensions, 5 independent coordinates mean 5 dimensions.
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In this case the extra axis is the worldline of the object we're descrbing and knowing any four cooridnates of an event will allow you to calculate the fifth.
It seems to me we don't have a 5 dimensional structure, instead we've got a 4 dimensional structure being described by a quirky coordinate system that uses 5 coordinates.
Your complaint is that any single world line does not fully utilize all 5 dimensions. But the set of all possible worldlines uses them, so they are fully utilized.
Consider a 3 dimensional substance, with one dimension curled up, which carries quantized waves that all happen to travel at the same speed c. If you know the speed of the particle in two of those dimensions you can compute the speed in the third dimension, so by your argument, there are actually only two dimensions.
What I'm saying here is just because you can mathematically eliminate a redundant piece of information from the description of a physical object certainly does not prove that that piece of information is not a part of the physical object. And eliminating these things can bring you a world of hurt in terms of making your physical intuition more difficult and your mathematics more complicated.
At the moment, if you are unfamiliar with the hundreds of papers written under the assumption of Euclidean relativity, you are not in a position to pass judgement on the efficacy of the technique. If you are not intimately familiar with both techniques you are not in a position to judge one against the other.
You can see that there are people who have studied this thing carefully for years and thought about it deeply, made calculations, rewrote the foundations of physics to fit the new assumption, etc. Having done this, we tell you that the grass is greener on this side of the fence.
To see the world from this side you will have to relearn the relativity that you already learned once. I admit that this is a mountain to climb. I admit that the only reason I had the time available to waste on this was because the economy turned down and it looked like a good time to take a vacation from my usual employment. Maybe you don't have this luxury. Life is short.
However, if you do decide to make the effort, the view from up here is beautiful and the weather is fine. The road was very difficult, more especially for a particle physicist than most, because it required that I rethink almost everything I thought I knew about particle physics. It looked like a real stupid idea many times to me, but eventually I worked out new ways of explaining the contradictions and they were simpler and more beautiful than the paradoxes that I was taught before.
Having arrived here at great effort, and experiencing great enjoyment, I will never leave, but I recognize that the effort to get here is beyond the capability of most at this time. To leave the fields where 99.99% of physicists live will give you solitude that may be unwelcome for most, and the path will require a nose for elegance that will evade most. It just ain't easy.
In the example of bringing 3 dimensions down to 2 in an unphysical way, one would notice that in 2 dimensions, there actually are two different choices for that undetermined 3rd velocity coordinate. The corresponding choice in Euclidean relativity is the choice of going forwards and backwards in time, as in the Feynman description of antiparticles. See Hans Montanus for a description of this in classical relativity.
Carl