In a way I like string theory and branes (M theory). Probably because I expect SpaceTime to be smooth and as we're talking about one dimensional 'strings' 'loops' (loop quantuum theory) or/and 'branes'. It makes a very weird kind of sense. But I do not like the idea of dimensions as 'singular' entities.

I don't think SpaceTime is defined like a 'Lego' myself. I think of it as a Jello where all goes into each other and the arrow of time creates 'particles' for us. At least I do so for the moment

When it comes to charge as a 'dimension'? I'm still not sure what a dimension should be seen as? But if you take something, not measurable in its own right but only as a outcome of a interaction, and lift it up to a dimension you will have problems.

Myself I'm thinking of 'Gravity' as a possible 'dimension', that and 'energy'. Both because I expect them to exist everywhere a 'SpaceTime' exists, but then we come to what we can quantize and there it seems as 'energy' only comes in 'quanta' which differs it from 'gravity', as far as I know. 'Charge' and 'energy' seems both to be quantize-able whereas 'gravity' still isn't. But I'm not sure on anything in fact

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You might want to define a wave as continuous, and so define 'energy' as continuous too, and you might be perfectly right there? But then we have 'frequency' and defining a 'wave' as 'vibrating', creating those 'peaks & throughs' defining its 'energy'?

Gravity doesn't, yet

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To see what I mean you can consider 'gravity propagating', like away from those binary stars spinning around each other. There you have two points of view to choose between. Either define it as a 'gravitational radiation' propagating at some 'frequency', or do as I and see it as the 'Jello' distorting itself, the 'distortion' moving under our arrow at the speed of light, as all 'motion' obeys that constant. Then you have a 'field' of a sort, like a spiders web defining a 'space' containing a 'distance' as defined macroscopically.

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You might then want to take the spiders web analogy a step further. In a spiders web the motion/vibrations in it travels at the speed of sound, alerting the spider to its prey getting caught in it. In 'SpaceTime' you instead have the speed of light in a vacuum defining that 'propagation'. So if we look at the 'web' you might want to define 'gravity' as instantaneous in a sense, that as I define it as being existent even where you can't 'measure' it. If you look at Newtons spheres we find a possible 'zero gravity' in the middle of any sphere of invariant matter. That it is unmeasurable there doesn't mean that it isn't existent as I see it, it simply mean what it states, it is unmeasurable.

So the 'web' becomes a 'dimension', in 3D + time macroscopically, and as I expect, probably all the way down past, and beyond, Planck scale, eh, maybe?

In that same manner we can find the idea of 'energy' existing on all scales, from 'virtual particles' to our 'SpaceTime'. So I'm of two minds there

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( Can you see why we need it in 'New theories'? It's getting real 'wild' here, ahem. )