Dear Heinrich Pas,
An enjoyable essay. You note that the truly unique factor of our language is "its ability to transmit information about things that do not exist at all... Thus "any large-scale human cooperation - whether a modern state, a media evil church, and ancient city, or an archaic tribe - is rooted in common myths that exist only in people's collective imagination."
But, as you say, "not all realities are equally fundamental."
You note that in the space-time concept of relativity observers moving with different speeds will measure different times in space, while the space-time distance ds is not directly observable. My essay reviews the history of relativity in a way that I hope you find interesting. I would appreciate any comments.
With regard to "information about things that do not exist at all", you note, for example, Heisenberg's creation of isospin to 'describe' proton and neutron. If one grants that protons and neutrons are in some fundamental sense 'real', this represents one of the first (of many) instances in which a mathematical projection is used to replace reality. It isn't even a particularly clean projection, as isospin symmetry assumes equal mass, and even this is not true. This projection-based approach continues to SU(3)xSU(2)xU(1) with the same problem. SU(3) assumes 'equal mass' but it is applied to problems where masses differ by two orders of magnitude.
Thus 'symmetry' (a.k.a. group theory) offers a powerful tool, but I believe ALL actual instances of 'symmetry' are approximate. In this way Heisenberg's projected Q-bit evolved to Bell's projected Q-bit which is the basis of "entanglement", which you seem to consider fundamental.
However I do agree that information is immaterial and relies on a material carrier and depends on the perspective of the observer. That is, only energy travels through space. If that energy crosses a threshold and changes a system's configuration, the system becomes "in"-formed and the informed structure represents the record of 'information', assuming a codebook or perspective is able to interpret it.
Thank you for a very well-written, interesting perspective on 'what is fundamental?'. I hope you find my essay interesting.
My best regards,
Edwin Eugene Klingman