UNCORRECTED PROOF 1 2 3 Matters are not so clear on the physical side 4 Olimpia Lombardi • Mario Castagnino 5 6 Ó Springer Science+Business Media B.V. 2010 7 Abstract According to ontological reductionism, molecular chemistry refers, at last, to 8 the quantum ontology; therefore, the ontological commitments of chemistry turn out to be 9 finally grounded on quantum mechanics. The main problem of this position is that nobody 10 really knows what quantum ontology is. The purpose of this work is to argue that the 11 confidence in the existence of the physical entities described by quantum mechanics does 12 not take into account the interpretative problems of the theory: in the discussions about the 13 relationship between chemistry and physics, difficulties are seen only on the side of 14 chemistry, whereas matters highly controversial on the side of physics are taken for 15 granted. For instance, it is usually supposed that the infinite mass limit in the Born- 16 Oppenheimer approximation leads by itself to the concept of molecular framework used in 17 molecular chemistry. We will argue that this assumption is implicitly based on an inter- 18 pretative postulate for quantum mechanics, which, in turn, runs into difficulties when 19 applied to the explanation of the simplest model of the hydrogen atom. 20 Keywords Molecular chemistry  Quantum mechanics  21 Born-Oppenheimer approximation  Quantum ontology 22 Introduction 23 According to ontological reductionism, chemical entities, when analyzed in depth, are 24 nothing else than very complex physical entities. In other words, molecular chemistry 25 refers, at last, to the quantum ontology; therefore, the ontological commitments of A1 O. Lombardi (&) A2 CONICET, Universidad de Buenos Aires Buenos, Aires, Argentina A3 e-mail: olimpiafilo@arnet.com.ar A4 M. Castagnino A5 CONICET, IAFE, Universidad de Buenos Aires Buenos, Aires, Argentina A6 M. Castagnino A7 IFIR, Universidad Nacional de Rosario, Rosario, Argentina 123 Journal : Small 10698 Dispatch : 1-7-2010 Pages : 8 Article No. : 9090 h LE h TYPESET MS Code : FOCH83 h CP h DISK 4 4 Found Chem DOI 10.1007/s10698-010-9090-9 Author Proof