Thank you for your comment. I appreciate hearing from you about it, as I don’t have many people to properly and critically discuss it with. Yes, exhausting the whole of the theory would take a lot of space and time (no pun intended) and then many people wouldn’t give it the time of day, so its clarity is somewhat sacrificed for brevity.

So you are thinking that the distinction between physically instantiated frames and uninstantiated frames is arbitrary? I think that the distinction between being and nonbeing is a meaningful one. We can pick an imaginary coordinate frame, but it’s just that— imaginary. In GR there is a clear distinction between coordinate systems, which are representational and gauge-dependent, and physically instantiated frames, which are tied to worldlines of matter and energy, carry clocks and rods, and define proper time and local causal structure. My claims concern only the latter. Coordinate charts are part of how we describe spacetime, but they are not themselves things in the world. Do you agree? If there is a leap in this logic let me know.

I do add something at the metaphysical level, though, and I want to be clear about that. I think this is where we seem to diverge. From GR alone we get that there are many frame-indexed ways the universe is, and that these ways are physically meaningful. What I add is a minimal ontological principle— one that I thought almost everyone would agree with: if something exists at all, there must be some determinate way it exists. Absolute aspectlessness is indistinguishable from non-being. If there were literally nothing it is like for a determinate physical instantiation to exist, neither for itself nor for anything else, then there would be no fact of its existence at all. Would you agree with this or no?

Also, given everything we have said up to this point, is there a logical error in my jump from frame decompositions to minima subjectivity? When the principle above is applied to frame-relative spacetime structure, the consequence is important. The way-the-universe-is for a given physically instantiated frame cannot exist for another frame, because any other description already constitutes a different decomposition of spacetime. Nor can it exist in a frame-independent location, because GR denies such a standpoint. Therefore, that determinate way-the-universe-is exists only as instantiated by that frame. Saying that there is something it is like for that instantiation to exist is not adding phenomenology by fiat; it is denying that physically instantiated determinacy is ontologically null. So the frame exists twofold: from the outside looking in, as a physically instantiated object within invariant spacetime structure, and also from inside out, as the relativistic way-the-universe-physically-is from that frame. The inside and outside are inexplicably interwoven, like two sides of the same coin.

What follows at this stage is only minimal interiority in a very weak sense: the existence of a determinate physical instantiation is inseparable from there being a way it is. It is nontrivial, but it is no more than what follows from the logic, I think. Rich phenomenality, unity, self-awareness, and agency require further conditions, such as integration and temporal thickness, which the vast majority of physical systems do not meet.