Interesting Evan. Let me be clear on one point though. Any suggestion that the fine-structure constant is a variable also must assume a arrow of time, a past-now-future. That's not entirely acceptable, to me then, ahem:) As I presume us (the universe, and all) to come from constants, those 'creating' the arrow we find. It would make this reasoning into a dog chasing its tail. I think of it as a 'ill defined field' of sorts, every 'point' in that 'field' using same constants (as locally defined measured.). And in a similar manner to we expect decoherence to come into play, I think we can expect a macroscopic arrow from local constants, scaling them up.

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'Scaling them up' just means introducing frames of reference in this game, interact and transform relative ones local measurements.

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Now let's turn it around a little.

Expecting constants to exist as variables presume a existing arrow from where they change, existing macroscopically as well as microscopically. It also presume that constants are not what a universe comes from, as they are variables, meaning that they have to look further for those even more ill-defined 'principles' that then should lead to 'constants'. The difference is one between using constants as the principles defining a universe, or assuming that they are a result of 'something else' leading to (variable) constants.

Or, it isn't a constant

In which case I still will argue that 'c' is one, though

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Hmm, think I'll slightly retract the one about a arrow of time 'not existing' at Planck scale

I do think it 'exists', but not as the macroscopic arrow we define. Locally it's equivalent to 'c' as I think and scaling 'c' down you will reach a place theoretically in where Planck scale set a limit for lights propagation. If you now use that definition as a 'Planck clock' instead, you equivalently can define it as at Planck scale you must find a 'frozen clock tick', demanding 'frames of reference' to create a arrow. And locally it is very well defined to me, that arrow, but as you put in more frames of reference, comparing between them, you will find time dilations and Lorentz contractions. Those coming into play due to the limit of 'c' over frames of reference, relative 'mass', 'motion', energy, all of which are definitions created over those frames of reference, interacting and transforming... And yes, following this line of reasoning we may define one single frame of reference as equivalent to one Plank length in one Planck time, meaning that this is the limits inside where it 'exists', possibly? The negative aspects of such a definition is that I can't see how to prove it, more than point out that from this reasoning you must have microscopic 'gravitational' time dilations, as well as Lorentz contractions, as soon as you introduce more frames, building up to matter, and its 'motion'. Energy is transformations to me.

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What the rest is, should be geometry, and gravity? You need something joining frames of reference into matter and the dimensions we find. I think (?) Einstein though about gravity and dimensions in a similar way, but as he defined it from a existing 'commonly same container universe' he expected a dimension more, in where observer dependencies could be made to disappear, to give us that universe. Using strict local definitions you still need something joining those points, but you don't need to get stuck on entanglements any longer, I think

. That as we are the ones defining the dimensions, from our measurements.