I've been reading about the Einstein hole argument, and i fail to understand what makes active diffeomorphisms "special" compared to passive diffeomorphismsm also known as good old coordinate transformations.
Supposedly this article is a good overview of the problem. I've read this, but i feel that i must be missing something, since i can't feel surprised by the fact that two different coordinate atlas that are identical up to some global time slice and differ afterwards (in the article they call it coordinate transformations that are the same before a global time slice and differ later) will imply (through the field equations) evolutions of the metric that are identical but they will also differ later. Yes, i keep saying to myself while reading this, of course they must differ when the coordinates differ and be equal when the coordinates are equal, that is what happens when you change coordinates!
Now, some other interpretation of the hole argument states that a solution to a GR coordinated system with matter will have a natural mapping to another solution to a completely different system with matter that so happens to have the same coordinate system. Not sure what that does even mean, a manifold is sufficiently defined with a collection of charts and coordinate transformations in the overlap of the charts, also known as a manifold atlas. (yes there are subleties for these assumptions when one is involved with exotic spheres or four dimensional spaces, where there are non-equivalent differentiable structures, but let's put a pin on that for now)
Some other interpretation is that you need matter (and actual observers) to actual pinpoint invariants that are preserved by these active diffeomorphisms, since all observables are done in relation with these. That is a fair statement, but seems to me pretty much devoid of any actual content, since it is natural that one will always make statements relative to, say, the earth, the sun, the milky way, even if the statements are written in manifestly covariant expressions, one will always take a collection of preferred charts to write fields in the given coordinates, which the measurement apparatus are calibrated and gauged against.
Is there something am i missing? i feel like i'm going nuts over the silliness i perceive in this argument