The problem of identifying the system and the environment in the phenomenon of decoherence

OLIMPIA LOMBARDI; SEBASTIAN FORTIN; MARIO CASTAGNINO

Amsterdam, Holanda

Conferencia; Second Conference of the European Philosophy of Science Association EPSA09; 2009

European Philosophy of Science Association

<!-- /* Font Definitions */ @font-face {font-family:SimSun; panose-1:2 1 6 0 3 1 1 1 1 1; mso-font-alt:宋体; mso-font-charset:134; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:3 135135232 16 0 262145 0;} @font-face {font-family:"@SimSun"; panose-1:2 1 6 0 3 1 1 1 1 1; mso-font-charset:134; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:3 135135232 16 0 262145 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:SimSun;} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The main purpose of this paper is to argue that decoherence is a relative phenomenon, better understood from a closed-system perspective according to which the split of a closed quantum system into an open subsystem and its environment is just a way of selecting a particular space of relevant observables of the whole closed system. In order to support this claim, we shall consider the results obtained in a natural generalization of the simple spin-bath model usually studied in the literature (Castagnino et al. 2010a). Our main thesis will lead us to two corollaries. First, the “looming big” problem of identifying the system that decoheres is actually a pseudo-problem, which vanishes as soon as one acknowledges the relative nature of decoherence. Second, the link between decoherence and energy dissipation is misguided. As previously pointed out (Schlosshauer 2007), energy dissipation and decoherence are different phenomena, and we shall argue for this difference on the basis of the relative nature of decoherence.