An Open-ended Quantum Universe by Tatsu Takeuchi

Djordje and Tatsu -

A brilliant essay providing an excellent survey of the issues. It plants a flag - the World is open-ended and emergent. But I finished reading it hoping for more. If the universe is emergent and open-ended (something with which I agree) what does it show and what can we draw from it?

I think you can go farther and I would be most interested in your reaction to my thesis. The world is emergent and open-ended - but those are qualities of autonoetic consciousness. And those qualities are manifest in the features of the universe over which FQXi is struggling - undecidability, incompleteness and all the rest.

I see this is the first comment on your essay. Welcome to the fray!

George Gantz, The Door That Has No Key: https://fqxi.org/community/forum/topic/3494

George Gantz,

open ended and emergent very well put. Good work,rated you highly. Is it all emergent from cognitive ability. pls read/rate-https://fqxi.org/community/forum/topic/3525.thanks all the best in the contest.

Hi Djordje and Tatsu

What a well written, interesting and really dense overview of ideas of current physics. What I specially like is, that you stay non dogmatic, although you state your case.

In my essay I tried a conceptual analysis of the structure of physical laws and speculate, that the fundamental laws and objects are themselves emergent and dependent on the possible relations of the whole. I also argue that these laws might change and give rise to the phenomenology of time as factual past and open future.

The openness of the future would be an extreme one: Not because the initial conditions are not known or the laws of evolutions not computable. But because of lack of the conceptual structure that would describe the future state.

I hope, you find the time to have a look to my essay and give your opinion.

Luca

Dear Profs. Minic and Takeuchi,

I loved reading your brilliant and thought-provoking essay!

Needless to say, we share a great deal of your views, and I am glad and most grateful that you cite my work more than once in your essay (your ref. [4]). Indeed, your discussion on the choice of a number field is deep and I also believe that it could be at the core of new ideas on the foundations of physics. In my essay, I develop further the concepts introduced by Gisin (and myself). I appreciated very much your section on potentiality vs actuality, which is something I am also most interested in (my main research project is on the quantum measurement problem!).

I would like to comment that this problem would arise in any irreducible probabilistic theory, besides quantum physics. In my essay I discuss a "classical measurement problem" in the context of our indeterministic alternative classical physics. Moreover, I relate this to causality. I hope you may find an interest in that, and I would appreciate your feedback, should you have time to read my contribution.

At last, I liked your conclusion on emergence and Wheeler's proposition of "law without law". In this respect, you may find interesting the work of Markus P Mueller "Law without law: from observer states to physics via algorithmic information theory" (https://arxiv.org/abs/1712.01826v4), which is conceived in a subjectivist spirit (similar to QBism) and it was acclaimed with a certain favour in the quantum foundations community.

I wish you the best of luck for the contest and I give you the top rating you definitely deserve.

Best wishes,

Flavio Del Santo

Dear Authors,

Your essay is written in good style and provides excellent review of issues. I would like to comment on the part concerning uncomputability since this word appears in the title of my essay. You provide account of different number systems which could have potential for physics but in my view there will be always question why these? In other words we have to go below the level of number systems when thinking about deepest foundations, the systems have to be emerging from something. In my essay this is done by considering uncomputable sequences from which the mathematical fields and other mathematical structures emerge due to the action of infinite permutation groups, there is enough headroom there for physics to be one to them. Physics would be then emerging from uncomputable substrate which means an ultimate theory without the baggage of assumptions and notions.

Best regards,

Irek Defée

Dear Djordje and Tatsu,

This essay is also open ended :) I enjoyed reading your essay. On the arrow of time, this question is also open ended and fundamental to understand what physics is. My colleague developed quantum mechanical solution on this problem as seen in his paper. As the background, the relationship between the information flow and arrow of time should be discussed. What do you think about such approaches from your viewpoint?

Best wishes,

Yutaka

Djordje & Tatsu,

Interesting discussion about an open-ended universe. It reminds me of philosophy/religion that speaks of a great spirit that co-creates though stars, galaxies, planets, bacteria, plants, and now humans, a great spirit w/o beginning or end. In such a realm, I imagine natural laws are emergent first at small distances and then large. Do all forces become one eventually, reverting back to the beginning? Hope you can check mine out: https://fqxi.org/community/forum/topic/3396

Regards,

Jim Hoover

Deeply respected Djordje Minic and Tatsu Takeuchi

Great job! A panorama of modern physics is drawn and all important problems are touched. A lot of original and unexpected. Our assessment of your work is the highest. Ten points! A very bright image of a physicist playing with the Multiversum! This is similar to the word guessing game that Wheeler described. We think a more accurate description is a game of chess. The evolution of the universe is the self-expansion of a chess game. The universe plays with itself ... Algorithms are inherent in this game. We talked about this in our essay.

Truly yours,

Pavel Poluian and Dmitry Lichargin,

Siberian Federal University.

Glad to see a shout-out of the Koopman-von-Neumann formulation of classical mechanics. It is endlessly fascinating to me that the same (empirically successful) theory can be mathematically described in so many different-looking ways.

Interesting to hear about the work of people like Aharonov taking a closer look at what 'measurement' really means. It makes a lot of sense to me that there are subclasses of measurements like 'weak measurements'. Maybe this is part of the key to the puzzle.

Maybe we should indeed be open to using different number fields in physics. After all, all measurement outcomes are rational numbers, and in that sense the real numbers are only a kind of idealization. Perhaps the use of p-adic numbers (or something else) should be investigated more closely.

Finally, I am very sympathetic to the idea that the fundamental laws (as we know them) are emergent from some different description. One thing that makes this hard to probe, though, is that there are probably many underlying models from which the Standard Model or something like it can 'emerge'. Also, if we find a deeper description, does that emerge from something else? Is it emergence all the way down? Thank you for the well-written essay!

John

Dear Tatsu,

I greatly appreciated your work and discussion. I am very glad that you are not thinking in abstract patterns.

"We also comment on the role of the choice of the number field in our descriptions of the regularity of natural phenomena and we argue for the emergent nature of the laws of nature at different scales of the Universe".

While the discussion lasted, I wrote an article: "Practical guidance on calculating resonant frequencies at four levels of diagnosis and inactivation of COVID-19 coronavirus", due to the high relevance of this topic. The work is based on the practical solution of problems in quantum mechanics, presented in the essay FQXi 2019-2020 "Universal quantum laws of the universe to solve the problems of unsolvability, computability and unpredictability".

I hope that my modest results of work will provide you with information for thought.

Warm Regards, `

Vladimir