From: eric@flesch.org (Eric Flesch) Newsgroups: sci.physics Subject: Minimalism and Bohm's Ontology Message-ID: <3e07a9f3.4863300@news.iconz.co.nz> Date: Tue, 24 Dec 2002 00:45:16 GMT NNTP-Posting-Host: 210.48.22.5 Bohm's "Undivided Universe" does a nice job of mathematically replicating quantum behavior using a starting concept of particles having well-defined positions not subject to the uncertaintly principle except for our ability to measure them. Experimentally, Bohm's approach can't be faulted. My own view however is that it runs afoul of a basic premise of ontological foundation. The issue is one of minimalism, i.e. a model with as few constructs as possible. Bohm first compares Bohr's wholeness approach with Dirac's "quantum state" and finds Bohr's approach to be internally more consistent and valid. I agree. (Digression: Bohm then makes the very useful point that most physicists today use Dirac's model, not Bohr's. This *really explains* the problem that physicists today seem to have with Copenhagen interpretations -- they don't practice Bohr's model, even though it is taught in the universities. OK, I'd missed that. That's why my "extreme Copenhagen" model gets jeered. We'll address that elsewhere. End digression.) Bohm then builds his ontological model as an alternative to Bohr's minimalist ontology. He attaches a new type of quantum field onto well-defined particles such that the observational outcome is that our measurement precision is limited by h. In this way he restores classical reality to the quantum world. Or so he claims. What I see wrong with Bohm's model that all it really achieves is to add an additional layer of classical reality onto the classical-quantum interface. The new quantum field attached onto particles remains unexplained ontologically except to map it into an implicate order which constrains it similar to Bohr's wholeness constraining quantum behavior by innate definition. So a final ontological model has not been solved by Bohm, only deferred. So what has been gained? Bohm's motivation in designing his model appears to have been his dissatisfaction with Bohr's solution which involves to some degree "unasking" the question. But empirically Bohm's solution gives us no further advantage, just the sense that perhaps things are more as they should be. But it is clear that at the bottom level, physical law is going to be counterintuitive and elegant. Perhaps combining these aspects makes it seem less elegant to us, so less attractive. I suspect this is what drove Bohm. But it does not make it right. Bohr's approach was seen by Bohm as being better than Dirac's. My own reading is that Bohr's approach is also better than Bohm's. Bohr adhered to a philosophy of minimalism which must be the correct avenue to the best model, i.e. a minimal model which conforms to experimental physical law. Where Bohr saw there were no answers, such as in reconciling wave and particle behavior, he chose to un-ask the question, as a harsh but necessary minimalist method. Wheeler, with his delayed-choice experiment decades later, was forced to the same philosophy. Much of the direction of physics since Bohr's day can be ascribed to the perceived ugliness of the Copenhagen ontology. This is anthropocentricism in charge of research direction, which of course doesn't work in the quantum domain. The usual direction of struggling against Bohr's model is to try to restore classical reality, as Bohm tried to do. I followed this course myself for some years. Then, realising it was impossible, I gave in, and found that, to my surprise, there was indeed beauty in Bohr's ontology; and, even more surprisingly, by following it to its extreme logical limits, that there is a classical reality to be recovered from it which is simple, consistent, and elegant. Easily simpler and more elegant than the models practiced by the heirs of Dirac who are so plentiful today. I'll be around in the year to come to remind people that Bohr got it right. Remember that only one man ever mastered Einstein -- Bohr. Eric