Dear Luca

Thanks for your reply. That is the difficult part. Zeh's book is entitled "The arrow of time", I am sure you will like it.

Good luck in the contest!

Regards

Israel

Hi Luca,

On the quantum eraser experiment, this is too strange for the general public. On the other hand, such gendanken experiments seem to "real" in the researchers mind. From this thoughts, the real experiments should be "confirmed" or "verified" in some sense. This shows that the boundary between the realistic understanding and the imagination is wobbly or depends on the background understanding. From the historical viewpoint on scientific development, I hope that our understandings are improved.

Best wishes,

Yutaka

Dear Dr Luca,

This is one more similarity with Dynamic Universe model.

It was proved by Dynamic Universe model by simulations, all the matter and radiation that are ejected out, from the Galaxy at the edge of Universe will be attracted by Universre and comeback into the Universe.... Have a look at my Blog.............

" https://vaksdynamicuniversemodel.blogspot.com/ "

Best Regards

=snp

Hi John,

Very good question! Thanks for asking it. By definition every quantity has do be defined and must be measurable within the theory. I would say as a first instance this can be decided formally within the theory. In the reconstruction in the essay you have a symmetry defining the basic quantities. Also the free evolution is defined. Then one needs an interaction, that correlates these quantities to another system or objects, which then serves transporting the information about the quantities of the first object to the other one. The interaction doing this is mostly defined by some gauge principles.

I would say, that quantum field theory, the standard model, are semantically closed theories, depending maybe on the Interpretation (relating to the measurment Problem). Except maybe for the time measurement, since time is entering the theory as external parameter and not as observable.

But also Newton classical mechanics might be a closed theory. Maxwell's theory also. Here I am not sure, if the length scales can be defined within the theory.

General relativity, I'm not sure if it is closable, because it needs rulers defined in another theory. It is questionable if a general covariant gheory can be a closed Theory, because no seaprable objects can be defined in it.

Now the question is: how do we know, this theory is realized? There are several problems here. One of them is connected to the Duhem-Quine thesis. In here to falsify theory trough observation needs always an auxiliary theory describing the measurement. Usually this theory is well established and no reason to doubt it. But for closed theories the observational theory is the same as the theory to be falsified. This looks really circular.

The objects and systems to be well defined must be separable from the rest. But this separability is only approximative. The rest can be modelled as external forces, that change the 'normal behaviour' of the system. But whether the theory has to be modified or the not normal behaviour explained by external forces might not be decidable from observation alone. See for instance dark matter vs. MOND.

Finally such a closed theory generated from symmetry and some principles is a big tautological construct. We might not expect to create some empirical theory from principles. So in order to give meaning to the concepts in the theory, the theory must contain Newtonian classical mechanics as limit, which is the language of our intuition.

Sorry. Long answer for a short question.

Luca

Dear Dr Luca,

Very good explanatory answer with wonderful knowledge. You touched Newtonian Gravity, MOND, GTR etc in cosmology in addition to quantum field theories. I was working on this Dynamic Universe Model using Newtonian Gravitation and got many results.

I was feeling sorry to say that you did not yet looked at my essay. I hope you will get some time before closure of this contest....

Give me your mail ID so that we can discuss even after this contest

Best wishes to your essay

=snp

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  • Post #30

Hi Luca,

In response to your comment on my essay.... I believe there is a single Arrow-of-Time: the radiation AoT (see my ref's. on ECD). The asymmetry between past and future in terms of memory stems from logical consistency:

"...and indeed, the 'memory' of our future is much more selective than that of our past. Had we 'remembered' also everything from our future, we would surely choose, whenever possible, to avoid its unpleasant aspects, thereby creating a paradox."

As you note, a future memory of a truly original `thing' is initially necessarily "fuzzy", as that thing is not yet present in one's normal experience (to be contrasted with `future memories' of simple variations of existing things, which need not be fuzzy).

I have thought a lot about the possibility of factoring-in our own limitations, as observers, into our description of `reality'. I once even thought that, since we are essentially some `representation' of the laws of physics, there is no real mystery as to why we can describe nature so effectively with our invented theories. But as with Goedel's theorem, you need an `outside look' at a physicist which, being a physicist, you are not privileged to. Ultimately, only a solipsistic stance is consistent, which takes you outside the scope of physics (or anything communicable for that matter).

I enjoyed reading your essay,

Yehonatan

Dear Luca Valeri Zimmermann!

We highly appreciate your serious work in the highest sense. We are happy to inform you that our rating of your essay is 10 points. Only one important issue needs clarification... Henri Poincare wrote of "hidden axioms". For example, we take a complete turn as something given. But you can imagine a world where the rotation around its own axis will never end! Can we extend your approach to worlds with other fundamental foundations?

We wish you a successful scientific work!

Truly yours,

Pavel Poluian and Dmitry Lichargin,

Siberian Federal University.

    Dear Pavel and Dimitry,

    Thanks a lot for your rating, your kind reply and the question.

    I am not sure about Poincaré's hidden axioms. I have read about the hidden definitions. Although axiom and definition might be the same. But to return to your question: Yes, I think - and that was exactly the point of my essay - that it is possible to apply it to different foundations. In my approach it is the symmetry group defining the foundation - the basic concepts. One can imagine, that under different environmental conditions different symmetries are realized. For instance in free space or near black holes. Leading to different fundamental laws and objects.

    The main difficulty is then on how to describe the change from one system to the other as objects do not maintain their identity and the fundamental laws and concepts change. I don't know, how one could do that.

    I imagine the following situation: In free space objects and system are well defined. (The free space or vacuum itself is not defined independently of the laws or symmetries. It is itself as the objects of the theory an emergent thing.) If there is an external force like gravity, the identity of the objects and the free laws can be maintained and the force is treated as an external disturbance. This is a good and well defined approximation as long the back reaction of the system is small enough. But when gravitational forces are becoming to big, the approximation do not hold any more. We have to look for new symmetries, which create or define new separable objects and systems. These determine new foundational concepts and new laws.

    Luca

    Hi Luca, this is a very interesting essay. I'll have to give this some thought. But I'm not entirely convinced by some of your examples. I like the way you've framed the argument in terms of semantically closed theories, but I'm not entirely sure such a theory even exists (but perhaps that it your point).

      Hi Ian,

      Thanks for your reply. The question you raise is very interesting. In short I would say, that the standard model is semantically closed and General Relativity is not. GR needs the laws of optics for the definition of the Geodesic, or QM (atomic spectra) for a length scale. There are indications, that general covariant theories are not semantically closable.

      On a mesoscopic, emergent level there might be Newtonian mechanics, chemistry, biology that are semantically closed.

      I want to stress 3 points, that are connected to the question:

      1. The meaning of physical concepts are defined by possible physical operations and hence the meaning depends on the laws they ought to describe. So there is something inherently circular in these theories. But this might be merely a self consistency requirement.

      2. There is a unity between the formal system and the physical system as the concepts are not defined independently.

      3. The separability condition as condition for the definability of concepts is always only realized as an approximation. Insofar semantically closed theories are never strictly realized. If separability is broken the environment can be modelled as external system with external forces (gravitation for instance) or heat bath (decoherence). If the back reaction of the system is too strong or the influence of external disturbance is too strong, one needs to find another separable systems, ie. symmetries within the system, that describe separable subsystems.

      Finally the main point, I want to make, is that under different environmental conditions (low gravity vs. black holes) one might have different semantically closed theories describing these systems and there might not exist a unified theory describing both.

      And another point is that semantically closed system might change. Such a change is not describable within one theory and is maybe untheorizable (as Daniel Sudarsky writes in his essay). I belief this opens new ways to talk about consciousness and free will.

      Luca

      Hi Luca,

      Very interesting. So the Standard Model is semantically closed? I guess I'm still not clear on what that means, then, because it seems to me that the Standard Model is built on quantum field theory which, in turn, is built on QM and SR. One could theoretically assume, I suppose, that SR is part of QFT and then take QFT (vis-a-vis the Standard Model) to be semantically closed, but that would seem to require that SR is itself semantically closed which doesn't make sense to me. So maybe I am missing the point entirely?

      Ian

      Hi Ian,

      why should SR not be closed or closable? SR basically means, that you have the Poincaré group as symmetry group. The irreducible representation define what a free particle is - given by the Casimir operators of the group: mass and spin. Then by gauche principles the interaction is derived. In QFT you have even, that particles are only defined as free particles, because the interaction changes the vacuum (which also depends on the particle definition) and would lead to different inequivalent representations in fock space ...

      So the Poincaré group defines, when a system is free and separable from the environment etc. It defines the observables (except maybe for time, which is really difficult!).

      The difficulty in general relativity is, that you do not have a global invariant symmetry group and cannot define invariant separable objects. That might be the cause, why it is not renormalizeable.

      Luca

      Hi Luca,

      Hmm. I guess I must not be understanding the concept yet. I mean, time isn't a minor variable in SR. It's a major component of it so it seems like there is still a bit of an issue since the Poincaré group can't deal with it as an observable. But, again, maybe I'm not understanding it fully quite yet.

      Ian

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