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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeMay 13th 2021
    • (edited May 14th 2021)

    At computational trilogy I made explicit the quantum version – here.

    As with the classical trilogy, it’s evident once you think about it.

    • CommentRowNumber2.
    • CommentAuthorDavid_Corfield
    • CommentTimeMay 13th 2021

    Can we think of anything as neat as:

    1. A proof of a proposition. (In logic.)

    2. A program with output some type. (In type theory and computer science.)

    3. A generalized element of an object. (In category theory.)

    Something to do with your propositions as projections idea?

    • CommentRowNumber3.
    • CommentAuthorUrs
    • CommentTimeMay 13th 2021

    Yes, it’s exactly the same dictionary. Just that the types/objects/spaces in the fibers are now linear.

    (And we notice that for “generalized element” we may equivalently say “cocycle” in all cases: classical, parameterized, quantum.)

    • CommentRowNumber4.
    • CommentAuthorUrs
    • CommentTimeMay 14th 2021
    • (edited May 14th 2021)

    In fact, without the parametrization/control-aspect, the quantum trilogy is already Melliès’s main point, on his p. 4 – I have tried to bring that out more clearly in the entry now, here

    • CommentRowNumber5.
    • CommentAuthorDavid_Corfield
    • CommentTimeMay 14th 2021

    Perhaps a little speculative for this time in the morning, but if we follow Susskind in

    • Copenhagen vs Everett, Teleportation, and ER=EPR Leonard Susskind, (arXiv:1604.02589)

    The universe is filled with subsystems, any one of which can play the role of observer. There is no place in the laws of quantum mechanics for wave function collapse; the only thing that happens is that the overall wave function evolves unitarily and becomes more and more entangled. The universe is an immensely complicated network of entangled subsystems, and only in some approximation can we single out a particular subsystem as THE OBSERVER.

    is there are quantum trilogy which is not classically controlled? Or is it that just ’quantum plain’?

    • CommentRowNumber6.
    • CommentAuthorUrs
    • CommentTimeMay 14th 2021

    Let me lay out the picture that I have at the moment, also so that you see where you fit in:


    Hypothesis H, full quantum version:

    For

    • a GG-orbi 10,1|32\mathbb{R}^{10,1\vert \mathbf{32}}-fold 𝒳\mathcal{X} (spacetime)

    • with geometric torsion-free Spin(10,1)\mathrm{Spin}(10,1)-structure (i.e. field of super-gravity)

    • further lifted to tangential Sp(2)\mathrm{Sp}(2)-structure τ\tau (anomaly cancellation),

    • consider the cocycle space π G τ(𝒳)\mathbf{\pi}_G^\tau(\mathcal{X}) of τ\tau-twisted equivariant differential 4-Cohomotopy (i.e. the C-field configuration G-space)

    • and then the GG-equivariant EE-cohomology cocycle space of its loop space E G (Ωπ G τ(𝒳))\mathbf{E}^\bullet_G\big( \Omega \mathbf{\pi}_G^\tau(\mathcal{X}) \big) (quantum states)

    • regarded as a GG-equivariant spectrum (e.g. with E=HE = H\mathbb{C} and 𝒳\mathcal{X} a D6D8D6 \perp D8 spacetime as in SS19 this has homotopy groups the weight systems on horizontal chord diagrams)

    Unwinding the definitions, this QFT encodes

    • quantum operations between quantum states of C-field configurations

    • associated with HH-fixed loci of the original spacetime orbifold 𝒳\mathcal{X}.

    • But since these loci are conical black brane loci (as in HSS 18) in the spacetime,

    • we see that we have a “classically controlled quantum system” where the classical control parameter says where in a holographic system we are:

      • in the bulk (11-fixed locus)

      • or on a brane (HH-fixed locus)

      • and if so on which of possibly several intersecting ones (choice of subgroup HGH \subset G).


    Now take this mathematical picture and compare to the current folklore in string theory. Within the large hand-waving error bars of the latter, this could match well, I think.

    • CommentRowNumber7.
    • CommentAuthorDavid_Corfield
    • CommentTimeMay 16th 2021

    Quite a vision!

    we see that we have a “classically controlled quantum system” where the classical control parameter says where in a holographic system we are

    I think this is the part I’ve heard least about before.

    I remember you giving an abstract general nPOV on holography, way back. Yes, here at holographic principle of higher category theory. Untouched for nearly a decade.