Skip to content

Quantum weak measurements and cosmology

0Citations
Citations of this article
9Readers
Mendeley users who have this article in their library.

Abstract

The indeterminism of quantum mechanics generally permits the independent specification of both an initial and a final condition on the state. Quantum preand post-selection of states opens up a new, experimentally testable, sector of quantum mechanics, when combined with statistical averages of identical weak measurements. In this paper I apply the theory of weak quantum measurements combined with pre- and post-selection to cosmology. Here, pre-selection means specifying the wave function of the universe or, in a popular semi-classical approximation, the initial quantum state of a subset of quantum fields propagating in a classical background spacetime. The novel feature is post-selection: the additional specification of a condition on the quantum state in the far future. I discuss “natural” final conditions, and show how they may lead to potentially large and observable effects at the present cosmological epoch. I also discuss how pre- and post-selected quantum fields couple to gravity via the DeWitt-Schwinger effective action prescription, in contrast to the expectation value of the stress-energy-momentum tensor, resolving a vigorous debate from the 1970s. The paper thus provides a framework for computing large-scale cosmological effects arising from this new sector of quantum mechanics. A simple experimental test is proposed. [Editors note: for a video of the talk given by Prof. Davies at the Aharonov-80 conference in 2012 at Chapman University, see quantum.chapman.edu/talk-13.]

Cite

CITATION STYLE

APA

Davies, P. C. W. (2014). Quantum weak measurements and cosmology. In Quantum Theory: A Two-Time Success Story: Yakir Aharonov Festschrift the Global Financial Crisis and the Indian Economy (pp. 101–112). Springer-Verlag Milan. https://doi.org/10.1007/978-88-470-5217-8_7

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free