Role of philosophy in QG (not too abstract)

oldman

Please forgive me for commenting that I think you're running before knowing how to walk here, Marcus. You are questioning whether a "quantum geometry theory" is "fundamental" or only an "approximate idealization" treating something that "is impossible to exist".

For someone like myself, who is still at a crawling stage, to decide such questions it is helpful to first consider how physics treats theoretically simpler and more tangible situations. Say like a solid lump of crystalline metal --- whose existence philosophers might doubt, but most physicists would accept.

A description of how the lump's constituent atoms are arranged while swimming in a sea of itinerent electrons is sufficiently fundamental for many practical purposes. But even at this simple level it is convenient to "talk about something which is impossible to exist", namely an abstract reciprocal space (which exists only in the minds of physicists) and, for the lump's electrons, an equally imaginary sea-surface in the same abstract space; the Fermi surface.

This makes it clear that physicists use quite complicated layered treatments even in relatively simple situations. In complicated and as yet unverified Quantum Gravity there are more layers. I think that to get down to a fundamental level one first needs to bring observers into the picture, as Fra often suggests, especially the nature of observers. I've said so in another recent (Dec 3) thread in this Forum, namely "Physics and Story-Telling".

czes

Wheeler said that XXI century will be a physics of the quantum information. We see it. Quantum computation is possible and developed.
The Holographic Principle suggests the information is fundamental.
I am imagining a computer program modeling a vacuum as a set of the points of the interaction between the quantum information and each this interaction has encoded a time dilation of the Plack time. We get then just the General Relativity of Einstein, very simple.
I am under impression that such a simple computer program creates a spacetime where the concetration of the Vacuum (information interaction) creates an arbitrary virtual reality.
You may call the increasing entropy forwards time and decreasing entropy backwards time (just a convention).
It is a speculation unless the Holographic Principle is true.