fredag den 15. juni 2012

Lever vi i en kvanteverden?

The Niels Bohr Archive, Blegdamsvej 17, Copenhagen.

History of Science Seminar:
Mon 2 July 2012, 14.15
Aud. A, Niels Bohr Institute

Henrik Zinkernagel
Dept. of Philosophy, University of Granada, Spain

Are we living in a quantum world?
Niels Bohr and the classical-quantum divide.

The spectacular successes of quantum physics have made it a commonplace to assert that we live in a quantum world. This idea seems to imply a kind of "quantum fundamentalism" according to which everything in the universe (if not the universe as a whole) is fundamentally of a quantum nature and ultimately describable in quantum-mechanical terms. Bohr’s conception of quantum mechanics has traditionally been seen as opposed to such a view - not least because of his insistence on the necessity of classical concepts in the account of quantum phenomena. Recently, however, a consensus seems to be emerging among careful commentators on Bohr to the effect that he - after all - did subscribe to some version of quantum fundamentalism. Against this consensus - and by re-examining the historical record - I will defend a variant of the traditional reading of Bohr in which 1) the answer to what an object is (quantum or classical) depends on the experimental context; and 2) any system, in principle, can be treated quantum-mechanically but not all systems can be treated that way at the same time. Inspired by this reading of Bohr, I will furthermore argue that there are good reasons to remain sceptical regarding quantum fundamentalism, also when modern developments such as decoherence studies and early universe cosmology are taken into account.