Dear Markus,
I very much enjoyed your thoughtful, masterfully written essay. It was so refreshing with its message of hope in comparison to all the usual discussions that want to turn back the clock of quantum mechanics to something more akin to classical physics or, metaphorically, Hilbert's program.
Years ago (22 or so!), I wrote a job application which I've just looked up. It started with these words, "The world we live in is well-described by quantum mechanics. What should we make of that? In a way, the answer to this question was once less positive than it is today. For although quantum theory is a tool of unprecedented accuracy ... the intellectual lesson we have come to
derive from it has been one ... of limitations. The best place to see this attitude is in a standard presentation of the Heisenberg uncertainty relations. It is almost as if the world were holding something back that we really had every right to possess: The task of physics, or so it was believed, is simply to sober up to this and make the best of it. ... In contrast to this ... the last ten years have seen the start of a significantly more positive, almost intoxicating, attitude about the basic role of quantum mechanics. This is evidenced no more clearly than [with quantum information and computing]. The point of departure in these disciplines is not to ask what limits quantum mechanics places upon us, but instead what novel, productive things we can do in the quantum world that we could not have done otherwise. In what ways can we say that the quantum world is fantastically better than the classical world?" Your paper brought back to me the romance of those lost days, but you did it so much better!
I had never previously thought about Goedel's incompleteness theorem in the positive way that you do, even though some other writers should have led me close to it. When I read your words on that point, I immediately thought, that's got to be right! "It is not a fundamental limit to what we can know, but a precious piece of knowledge about a non-property of the structure that we have discovered"--Beautiful!
Incidentally, in this paper of mine,
https://arxiv.org/pdf/1601.04360.pdf
I transcribed an entry from one of John Wheeler's notebooks that blew me away when I first ran across it. I don't think it's exactly what you have in mind, but here's the little story I wrote when introducing it: "Despite the dubious connection to anything firmly a part of QBism, I report Wheeler's idea because it seems to me that it conveys some imaginative sense of how the notion of 'birth' described here carries a very different flavor from the 'intrinsic randomness' that [Adan Cabello] and others seem to be talking about. ... Imagine along with Wheeler that the universe can somehow be identified with a formal mathematical system, with the universe's life somehow captured by all the decidable propositions within the system. Wheeler's 'crazy' idea seems to be this. Every time an act of observer-participancy occurs (every time a quantum measurement occurs), one of the undecidable propositions consistent with the system is upgraded to the status of a new axiom with truth value either TRUE or FALSE. In this way, the life of the universe as a whole takes on a deeply new character with the outcome of each quantum measurement. The 'intrinsic randomness' dictated by quantum theory is not so much like the flicker of a firefly in the fabric of night, but a rearrangement of the whole meaning of the universe."
You caused other thoughts in me as well. In the paper linked to above, I emphasized in a small piece of it that QBism shares *some* of its elements with a structural realism. But most philosophers of science I've told this to have been (predictably) dismissive. It's hard to say what stands in their way, except possibly that if an idea is associated with QBism, it's got to be bad! Upon reading you, however, I got a vision on how I might break the impasse: Make up a new name, a new distinction! Thus, from here out I will dub QBism's distinctive flavor "normative structural realism." But I will discuss this with you offline sometime.
In any case, I write all of this to let you know, in my eyes your essay has everything that should be expected of a winner of this contest. I learned a number of things from you, but mostly your essay caused me to think over and over about its contents all week. It hasn't left my mind, and that's a mark of distinction in an old doddering mind like mine!
All the best,
Chris Fuchs
