Users without a subscription are not able to see the full content.

## Jim Baggott

Print publication date: 2020

Print ISBN-13: 9780198827856

Published to Oxford Scholarship Online: January 2020

DOI: 10.1093/oso/9780198827856.001.0001

Show Summary Details
Page of

PRINTED FROM OXFORD SCHOLARSHIP ONLINE (www.oxfordscholarship.com). (c) Copyright Oxford University Press, 2020. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 03 June 2020

# Von Neumann and the Problem of Quantum Measurement

## The ‘Collapse of the Wavefunction’

Chapter:
(p.219) 11 Von Neumann and the Problem of Quantum Measurement
Source:
The Quantum Cookbook
Publisher:
Oxford University Press
DOI:10.1093/oso/9780198827856.003.0012

Heisenberg was an ‘anti-realist’. Although Bohr was infamously obscure in many of his writings, it seems that he adopted a generally anti-realist interpretation, too. As their debate became more bitter, in early June 1927 Pauli was called in to mediate. With Pauli’s help, they forged an uneasy consensus, which became known as the Copenhagen interpretation. Einstein didn’t like it at all, setting the stage for a great debate about the quantum representation of reality. Although von Neumann’s formalism broadly conforms to the Copenhagen interpretation, he saw no need to introduce an arbitrary split between the classical and quantum worlds. But eliminating the split poses the problem of quantum measurement: when scaled to classical dimensions, a superposition of different measurement outcomes appears contrary to our experience, exemplified by the famous paradox of Schrödinger’s cat. Von Neumann was obliged to break the infinite regress by postulating the ‘collapse of the wavefunction’.

Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service. Public users can however freely search the site and view the abstracts and keywords for each book and chapter.