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opencog-learn commits / f95d19c

FP ghosts, oh my.
f95d19ccc56e0c3cf95e91518bb420793e549816
by Linas Vepštas <linasvepstas@gmail.com> · 2026-01-15T18:52:44.000Z

Changed files (1) +404 -0

learn-lang-diary/here-and-now/here-and-now.lyx +404 -0
……@@ -2513,6 +2513,410 @@ explanation
25132513 well,
25142514 so far,
25152515 I can't offer one.
2516\end_layout
2517
2518\begin_layout Standard
2519So what have I learned,
2520 so far?
2521 Well,
2522 the natural topology applies to the past (and not some
2523\begin_inset Formula $p$
2524\end_inset
2525
2526–adic or archimedian metric topology) and that Cartesian space is characterized by the reals (and not the Cantor set) and that the present is a Hilbert space (of very high dimension,
2527 if not infinite,
2528 then at least of dimension
2529\begin_inset Formula $10^{80}$
2530\end_inset
2531
2532,
2533 the number of fermions in the universe) and that there is a map from the present,
2534 from this Hilbert space,
2535 to the Cartesian past,
2536 having the notational algebraic form
2537\begin_inset Formula $\left\langle x\right.\left|\psi\right\rangle $
2538\end_inset
2539
2540.
2541
2542\end_layout
2543
2544\begin_layout Standard
2545What do I not know or understand?
2546 How it is that Hilbert–space–occupying quanta in the present appear to get localized in the Cartesian past.
2547 I look out my window,
2548 and I see a tree,
2549 and I know that tree is made of fermions which have become localized in the past,
2550 not with probability
2551\begin_inset Formula $p=\left|\left\langle x\right.\left|\psi\right\rangle \right|^{2}$
2552\end_inset
2553
2554 but with probability
2555\begin_inset Formula $p=1$
2556\end_inset
2557
2558:
2559 those fermions in my tree are located there,
2560 and not in some mountain in Colorado.
2561 It is this localization into Cartesian space from Hilbert space,
2562 by means of probabilistic calculations,
2563 that is the source of unease.
2564
2565\end_layout
2566
2567\begin_layout Standard
2568I keep using the word
2569\begin_inset Quotes eld
2570\end_inset
2571
2572fermion
2573\begin_inset Quotes erd
2574\end_inset
2575
2576 because spin–1/2 is somehow key to this process.
2577 Light is massless,
2578 and lives on–shell for the most part,
2579 and appears to be
2580\begin_inset Quotes eld
2581\end_inset
2582
2583part of the present
2584\begin_inset Quotes erd
2585\end_inset
2586
2587,
2588 only.
2589 I cannot put light
2590\begin_inset Quotes eld
2591\end_inset
2592
2593into a box
2594\begin_inset Quotes erd
2595\end_inset
2596
2597 (say with mirrors and lenses) and publish a paper that says
2598\begin_inset Quotes eld
2599\end_inset
2600
2601my box,
2602 which existed in the past,
2603 briefly caged light and fixed it to a physical location
2604\begin_inset Formula $\left(x,y,z\right)$
2605\end_inset
2606
2607 for an extended period of time.
2608\begin_inset Quotes erd
2609\end_inset
2610
2611 Because,
2612 if I made that claim,
2613 it would be tantamount to making the claim that I was able to manipulate light so that
2614\begin_inset Formula $x^{2}+y^{2}+z^{2}-t^{2}\ne0$
2615\end_inset
2616
2617 for an extended range of time
2618\begin_inset Formula $\Delta t$
2619\end_inset
2620
2621 – but this is impossible.
2622 One cannot grab a hold of light and keep it off–shell,
2623 the way I can keep a book on my library shelf.
2624
2625\end_layout
2626
2627\begin_layout Standard
2628Thus,
2629 I conclude that light is necessarily a part of here and now;
2630 and more:
2631 the past null light–cone is a part of here–and–now,
2632 also.
2633 Of course,
2634 one can hypothesize massive Klein–Gordon spin–zero particles,
2635 but these do not exist in nature.
2636 Of course,
2637 we can point at the
2638\begin_inset Formula $W^{\pm}$
2639\end_inset
2640
2641 and
2642\begin_inset Formula $Z^{0}$
2643\end_inset
2644
2645 bosons,
2646 and say that they have mass,
2647 but these are dismissively microscopic;
2648 the relationship between past and present in that microscopic world might be,
2649 could be,
2650 probably is rather different from the relationship between past and present in our macroscopic world.
2651 So,
2652 for the present discussion,
2653 the microscopic theory encoded in the Standard Model has to be dismissed as irrelevant.
2654 The macroscopic theory of cosmology,
2655 however,
2656 has to be a part of here–and–now:
2657 I have seen the Horse–Head Nebula with mine own bare–naked eyes (admittedly with the help of a light amplifier and a rather large scope,
2658 some 18 inch or 24 inch Newtonian.) Those photons were very much on–shell,
2659 and were very much a part of here–and–now for the duration that my eyeball was pressed against the reticle.
2660 To conclude:
2661 fermions are the bridge between past and present.
2662\end_layout
2663
2664\begin_layout Standard
2665I guess that this forces me into pondering (yet again)
2666\begin_inset Quotes eld
2667\end_inset
2668
2669what about spin structures
2670\begin_inset Quotes erd
2671\end_inset
2672
2673?
2674 If the past is adamantly Riemannian,
2675 I also know that I can define spin structures on Riemannian manifolds,
2676 and those spin structures are somehow
2677\begin_inset Quotes eld
2678\end_inset
2679
2680more general
2681\begin_inset Quotes erd
2682\end_inset
2683
2684 or
2685\begin_inset Quotes eld
2686\end_inset
2687
2688more flexible
2689\begin_inset Quotes erd
2690\end_inset
2691
2692 or
2693\begin_inset Quotes eld
2694\end_inset
2695
2696encode more structure
2697\begin_inset Quotes erd
2698\end_inset
2699
2700 than the Riemannian manifold itself.
2701 What I do not know of is how to Hilbert–space–ize the Clifford algebras that are used to construct the spin structures...
2702 or rather,
2703 I don't know who to quantize.
2704 I know how to define a Dirac operator on any Riemannian manifold,
2705 and the corresponding spinor fields,
2706 but these fields are
2707\begin_inset Quotes eld
2708\end_inset
2709
2710classical
2711\begin_inset Quotes erd
2712\end_inset
2713
2714;
2715 they are not quanta.
2716 They obey equations of motion given by that Dirac operator,
2717 and they
2718\begin_inset Quotes eld
2719\end_inset
2720
2721propagate
2722\begin_inset Quotes erd
2723\end_inset
2724
2725 on–shell.
2726 Or rather,
2727 solving them gives a singular solution,
2728 the
2729\begin_inset Quotes eld
2730\end_inset
2731
2732classical
2733\begin_inset Quotes erd
2734\end_inset
2735
2736 solution,
2737 and not a superposition of solutions.
2738 There is only one manifold,
2739 there is only one field on that manifold,
2740 there are no
2741\begin_inset Quotes eld
2742\end_inset
2743
2744many worlds
2745\begin_inset Quotes erd
2746\end_inset
2747
2748.
2749 To conclude,
2750 I know how to define fermions in such a way that they obey classical equations of motion,
2751 and form a classical,
2752 non–quantized field.
2753\end_layout
2754
2755\begin_layout Standard
2756Do I know how to create a quantized fermion field?
2757 I dunno.
2758 This is a trap.
2759 Answering this question is a trap.
2760 I can say
2761\begin_inset Quotes eld
2762\end_inset
2763
2764yes,
2765 of course I do!
2766\begin_inset Quotes erd
2767\end_inset
2768
2769 and jot down
2770\begin_inset Formula $Z=\int e^{-iA}$
2771\end_inset
2772
2773 for some action
2774\begin_inset Formula $A$
2775\end_inset
2776
2777 that includes fermion fields and so
2778\begin_inset Quotes eld
2779\end_inset
2780
2781a hah,
2782 I have quantized it!
2783\begin_inset Quotes erd
2784\end_inset
2785
2786 This is true in some very narrow,
2787 technical sense,
2788 but false in the general sense,
2789 because if those fermions have mass,
2790 I don't know how to write down the back–reaction of those with gravity.
2791 I don't know how to do
2792\begin_inset Quotes eld
2793\end_inset
2794
2795many–worlds with gravity
2796\begin_inset Quotes erd
2797\end_inset
2798
2799.
2800 But lets ignore gravity for now.
2801 I'm not sure I know how to go from second quantization back to first quantization,
2802 or how to go from the Lagrangian description back to the Hamiltonian description.
2803 Gut sense seems to say that the Hamiltonian description is appropriate for the here–and–now,
2804 because the Lagrangian description requires time derivatives,
2805 and time is problematic;
2806 the Hamiltonian description avoids the need to have some explicit time coordinate.
2807 Now,
2808 I do know that if I want to toggle between these two interaction pictures,
2809 the Lagrangian and the Hamiltonian,
2810 and I want these two to have gauge fields in them,
2811 then I have to invoke the mechanics of Fadeev–Popov ghosts.
2812 But
2813\begin_inset Quotes eld
2814\end_inset
2815
2816that's just mechanics
2817\begin_inset Quotes erd
2818\end_inset
2819
2820,
2821 right?
2822 There aren't dynamical equations,
2823 there,
2824 for these ghosts.
2825 And that's OK,
2826 because if they were dynamical,
2827 it would be a problem.
2828\end_layout
2829
2830\begin_layout Standard
2831So is this a red herring,
2832 a distraction,
2833 or is it some necessary ingredient?
2834 If I want to say that the bridge between past and present is embodied in fermions,
2835 and if I want to say that light,
2836 or gauge fields,
2837 exist only in the present,
2838 and never in the past,
2839 and if I want to employ a Hamiltonian picture for the present,
2840 then I guess I have to also include Fadeev–Popov ghosts as one of the ingredients for the present?
2841 Or is that some bogus arcane distraction?
2842 I've already claimed that
2843\begin_inset Quotes eld
2844\end_inset
2845
2846gravitation is a bogus arcane distraction
2847\begin_inset Quotes erd
2848\end_inset
2849
2850,
2851 so why not FP?
2852 Is FP just some accounting tool,
2853 needed to make the books balance,
2854 or is it something more?
2855 The ghosts are not dynamical,
2856 which is great,
2857 because,
2858 in a sense,
2859 only the dynamical things in the present can enter the past.
2860 Well,
2861 photons are dynamical,
2862 but are not part of the past...
2863 sometimes,
2864 as I write this stuff,
2865 it feels like stupid word games.
2866 Who is to say what is or is not part of the past?
2867 We can't go there,
2868 we are imprisoned in the present,
2869 and have only memories of the past,
2870 so its kind of nuts to say
2871\begin_inset Quotes eld
2872\end_inset
2873
2874something is in the past
2875\begin_inset Quotes erd
2876\end_inset
2877
2878,
2879 when we can only say
2880\begin_inset Quotes eld
2881\end_inset
2882
2883there is a phenomenon called object persistence that is fundamental to perception and memory
2884\begin_inset Quotes erd
2885\end_inset
2886
2887.
2888 The word games identify fermions as having something to do with object persistance...
2889 but the word games also seem to indicate that
2890\begin_inset Quotes eld
2891\end_inset
2892
2893the past does not exist
2894\begin_inset Quotes erd
2895\end_inset
2896
2897 (except in the platonic sense) and that the past is,
2898 properly speaking,
2899 an impression,
2900 a structure,
2901 encoded/entangled into the here–and–now of the present.
2902\end_layout
2903
2904\begin_layout Standard
2905OK,
2906 well,
2907 I'm hitting a brick wall,
2908 again.
2909 So perhaps this is a good time to call it quits.
2910 Is there a summary I can make?
2911 Well,
2912 not really...
2913 I've listed many ingredients for the cake,
2914 with the newest one,
2915 FP ghosts being either a distraction,
2916 or being perhaps somehow important.
2917 Fuck me.
2918 I cannot summarize this mess.
2919 Later.
25162920
25172921\end_layout
25182922