From chemistry-request@ccl.net Sun Jun 1 16:09:04 2003 Received: from smtp3.server.rpi.edu (smtp3.server.rpi.edu [128.113.2.3]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h51K94gC029906 for ; Sun, 1 Jun 2003 16:09:04 -0400 Received: from webmail.rpi.edu (webmail.rpi.edu [128.113.26.21]) by smtp3.server.rpi.edu (8.12.9/8.12.9) with ESMTP id h51K92iI009416; Sun, 1 Jun 2003 16:09:03 -0400 Message-Id: <200306012009.h51K92iI009416|at|smtp3.server.rpi.edu> Content-Type: text/plain Content-Disposition: inline To: scerri|at|chem.ucla.edu From: "Dr. N. SUKUMAR" Organization: Rensselaer Polytechnic Institute Cc: chemistry|at|ccl.net X-Originating-Ip: 64.159.96.38 Mime-Version: 1.0 Reply-To: "Dr. N. SUKUMAR" Date: Sun, 01 Jun 2003 16:09:02 EDT X-Mailer: EMUmail 4.00 Subject: Re: CCL:orbitals X-Scanned-By: MIMEDefang 2.28 On Fri, 30 May 2003 16:07:46 -0700 Eric Scerri wrote: > > > As somebody working in philosophy of science and more specifically > philosophy of chemistry I have found the recent discussion very > interesting. > While for my part, I have always been a "working computational chemist", I've studied with great interest the debates between Bohr, Einstein, Bohm and others. > > There is a long-standing debate in philosophy of science going back > for hundreds of years which in modern terminology is referred to as > the realism versus anti-realism debate... > > Finally, it should also be recalled that the most widely held > interpretation of quantum mechanics, the Copenhagen interpretation, > is essentially an anti-realistic interpretation regardless of what > people like Einstein and David Bohm may have wanted... While I agree that this is indeed a long-standing debate, the problem was exacerbated by the insistence of some, like Bohr and Heisenberg, that science is concerned not with the physical universe ("physical reality") per se, but with human knowledge/awareness of the physical universe. While we might agree that the latter does fall within the purview of science, most scientists today would opine that it falls within the discipline of cognitive science rather than physics. Few are the physicists who are able to get grants to study human cognition using acceleraters rather than EEGs and MRIs! > > For example > phlogiston was initially quite useful and successful in explaining > many chemical facts. Some people may even have believed that this > meant that phlogiston was a real physical entity and yet as everybody > knows it turned out to be a mistake. Perhaps a better example might be the aether and spacetime. While most people today might say that the aether theory was a big mistake, I regard spacetime as simply a modified version of the aether concept, in the same way that modern DFT helped reformulate the concepts of hardness and electronegativity. So does spacetime "exist"? Or do orbitals have "physical reality" (to distinguish it from the real/imaginary/complex classification)? To me, questions like this are inherently unanswerable, or at least unanswerable at the level of science. Such questions belong in the realm of philosophy and religion. Science can ask: is the phlogiston concept still useful? The answer there is no! Is the orbital concept still useful? Here the answer is that, within bounds, yes! But is it absolute? Can it explain all observations? Certainly not! Now a more difficult question (and one that calls for subjective judgements): is it a reasonable working model? Here opinions seem to differ. It is possible to formulate and rationalize most of our observations entirely without reference to orbitals. Several successful theories, such as the variational formulation of density functional theory and some Green's function theories, do just this. Does this make the orbital concept any less valid? No, but it does argue against religious beliefs of orbital reality. Does this make orbitals any less useful? Again, no. The most widely used theoretical formulations (Hartree-Fock, CI, Kohn-Sham DFT) are still constructed in terms of orbital expansions. But I would argue that it makes little sense to try to "explain" all our observations in terms of orbitals, a practice which is still widely prevalent. > > except in the general sense that all scientific > theories and approaches are eventually refuted. This view, called > the pessimistic meta-induction, ... > > There seems to be an inconsistency here: that of extrapolating beyond the known range of validity of the model. I would modify this to say that all scientific theories should be, in principle, falsifiable or refutable. A theory that isn't so is not science, but religion. The only exceptions are axioms and they are to be regarded as merely working hypotheses. Axioms are not falsifiable, but they can cease to be useful. In science there are no self-evident truths. Problems arise when axioms are confused for facts. Replacement of one set of fundamental axioms (as for example, the centrality of the earth) for another often leads to a major paradigm shift in science. Dr. N. Sukumar http://www.drugmining.com/ Visiting Scientist Rensselaer Department of Chemistry and Wadsworth Center, New York State Dept.of Health From chemistry-request@ccl.net Sun Jun 1 18:22:20 2003 Received: from hotmail.com (law15-f86.law15.hotmail.com [64.4.23.86]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h51MMJgC001993 for ; Sun, 1 Jun 2003 18:22:20 -0400 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sun, 1 Jun 2003 15:22:19 -0700 Received: from 199.190.31.235 by lw15fd.law15.hotmail.msn.com with HTTP; Sun, 01 Jun 2003 22:22:19 GMT X-Originating-IP: [199.190.31.235] X-Originating-Email: [einew^at^hotmail.com] From: "Irene Newhouse" To: chemistry^at^ccl.net Subject: Re: CCL:orbitals Date: Sun, 01 Jun 2003 12:22:19 -1000 Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: X-OriginalArrivalTime: 01 Jun 2003 22:22:19.0408 (UTC) FILETIME=[43C5E100:01C3288C] Dr. N. Sukumar wrote: "Problems arise when axioms are confused for facts. Replacement of one set of fundamental axioms (as for example, the centrality of the earth) for another often leads to a major paradigm shift in science." Hear, hear! I was fortunate to have a chemistry teacher in high school who, galvanized by some of the debates about evolution that took place & are still taking place, made sure we understood the difference between facts & theories. He also discussed the pitfalls of becoming so attached to your theories you fail to discard them when they're no longer useful, the necessity for falsifiabilty & the difference between being a scientist using a theory & a private individual concerned about 'absolute truth'. Unfortunately, a teacher with his level of awareness is all too rare [and he was fired at mid-term for smoking marijuana & replaced by a teacher who didn't, but also didn't remember the concept of d orbitals but kept the job for 20 or more years] & most people who graduate high school don't have much of a clue as to the nature of science. Which fuels some of the sillier controversies that exercise the public. Irene Newhouse _________________________________________________________________ The new MSN 8: smart spam protection and 2 months FREE* http://join.msn.com/?page=features/junkmail