Hans Christian Öttinger

“According to Henry Margenau [7], “[the epistemologist] is constantly tempted to reject all because of the difficulty of establishing any part of reality” (p. 287). But, again in the words of Margenau, “It is quite proper for us to assume that we know what a dog is even if we may not be able to define him” (p. 58). More classically, a similar idea has been expressed by David Hume: “Next to the ridicule of denying an evident truth, is that of taking much pains to defend it” (see p. 226 of [8]). In this spirit, I try to resist the temptation of raising more questions than one can possibly answer, no matter how fascinating these questions might be. Philosophy shall here serve as a practical tool for doing better physics. I try to use philosophy in a relevant and convincing way, but I am certainly not in a position to do frontier technical research in philosophy.”

In “A Philosophical Approach to Quantum Field Theory” by Hans Christian Öttinger

The accretion of presumptions based upon a fundamental epistemological error by the ancient Greeks has indeed led to dramatic results. Progress, on the other hand, is an illusion based upon the same epistemological error. There is only a redefinition of a fundament that is inherently subject to interpretation. The presumed linearity of time (progress) finds its genesis in the same epistemological error. Furthermore, this epistemological error by some Greeks is antecedent to any attempt to characterize the nature of the alleged fundamental building block(s). The locus of the epistemological error is in the initial presumption of an invariant fundament. I'm no longer a scholar but weren't the observations of Heraclitus regarding the pursuit of truth influenced by Platonists? While (in my opinion) Heraclitus acknowledged that the object of perception was subject to interpretation the Platonists adapted this to suit their presumptions regarding the nature of the perceived. Implicit in the Platonist's assertion "Nature loves to hide" is the presumption that a physical invariant does exist; it is merely elusive.

Epistemology is to scientists as air is to birds: An appreciation of the absolute nature of the medium not only allows them the potential to fly in any direction, it also explains the nature and inevitability of the paradigm shift.

"To do maths all you need is a pencil, some paper, and a bin. To do philosophy, all you need is a pencil and some paper." For every philosophy tract you can raise one equally valid that conflicts. They are all stories. And by this token is philosophy just "a vitally important subject" or does it "explain" contrary to some comments? It is instead something that, like the stories of religion, becomes socially acceptable in precisely that moment that it is accepted that they are stories to tell in specific whittle-time-away meetings?

Presumably testing augurs the same popularity among physicists. With Popper we get a testable theory for science and its core of testing both (by validation with "meta" testing). And it fills out the shell of progress by predicting how non-working theories gets thrown out, and how the finite number of possibilities (finite observable universe!) can be pared to a working theory. It is my thinking that when theory of science is wrested from philosophy of science and is remitted to science of science where it naturally places, testing will remain as a core theory (there is a testable definition given by Deutsch in his "The Fabric of Reality" - specific actions results in specific reactions; also, Deutsch gives a short rejection of solipsism anyway, saying it isn't a solid idea (basically, a solipsist have to accept that most of what his brain invents is lawful, so there remains very little leeway for "creative invention"). It is a more realistic [sic] method than asking to resolve everything perfectly at once. Yet it drags in causality, constraints and everything we can which, and devolves simply to the observation-observables basis of quantum physics. (Or Newton's third law if we restrict to classical physics.)

I am glad to see some defence of the philosophy of science in Öttinger’s approach to QFT. The way I see it, philosophers of science have colonised intellectual ground that has been abandoned by scientists - abandoned possibly for very good reasons - perhaps as part of the process that continually divides science up into narrower and narrower specialisms as more and more stuff is discovered - so the philosophy gets slewed off into its own niche. It does disappoint me, though, that, in general, scientists are not interested in discussing the more philosophical end of their subject but are content to "shut up and calculate". When I studied Physics many eons ago, I was very disappointed to find that the tutorials were not round-table discussion fora on the meaning of phrases such as "curved spacetime", but consisted entirely of going through the problems in the problem sheet. And scientists are incredibly sloppy with their terminology (to my mind applying a word which is in common usage such as "curved" to 4-dimensional spacetime is a recipe for confusion and misinterpretation, even more so when "spacetime" inevitably gets shortened to "space"). Someone has to step in and clean it all up a bit. To me, philosophy of science plays the same role in relation to science itself as analysis does to calculus - it is tedious, laborious, and takes ages to prove very little - but it is essential in order to justify everything else. See what is happening with the so-called Measurement Problem.

“By construction, a Fock space allows us to go from the Hilbert space for a single entity to a Hilbert space for many independent entities, where the number of these entities can vary – no more, no less. We have not yet made any reference to any Hamiltonian, so that we cannot speak about interacting, noninteracting, or free particles; nor have we provided any information about time evolution in Fock spaces. Why the Fock space for independent particles plays such a fundamental role even for interacting theories will be recognized in Section 1.2.3.2 (see p. 69).”

In “A Philosophical Approach to Quantum Field Theory” by Hans Christian Öttinger

One of the main hassles in implementing numerically the calculations of operators is the quite distinct way of indexing in H- and F-Spaces. This is made more tricky by the differences between allowed states for fermions and bosons (e.g., we’ve got to use reshaping cycles and crap like that). Working in H-spaces offers an clear-cut payoff from the physical point of view, since one has a clear explicitation of the degrees-of-freedom associated to each particle, and a better indexing of states. On the other hand, because I’m coming from a Computer Science field, a couple of issues arises from the point of view of numerical implementation (too technical to write about here). Back in the day, 2nd quantization and the F-Space were presented as the natural way to deal with quantum systems made of many indistinguishable particles, leaving the feeling that the H-Space description could be left behind (lol). While this is quite true for the description of quantum states of those systems, the computation of some specific observables may be more conveniently pursued using the H-Space construct (Öttinger only uses F-Space as an auxiliary as well, as it should be: “The field is used only as an auxiliary quantity for the heuristic motivation of collision rules and quantities of interest with the proper symmetries – and to establish contact to the usual formulation of Lagrangian quantum field theory.”)

The way he derived his Quantum Master Equation is nothing short of masterful..."Melikes" it...… (plus d'informations)