  Deutsch and Hayden claim to have provided an account of quantum mechanics
which is particularly local, and which clarifies the nature of information
transmission in entangled quantum systems. In this paper, a perspicuous
description of their formalism is offered and their claim assessed. It proves
essential to distinguish, as Deutsch and Hayden do not, between two ways of
interpreting the formalism. On the first, conservative, interpretation, no
benefits with respect to locality accrue that are not already available on
either an Everettian or a statistical interpretation; and the conclusions
regarding information flow are equivocal. The second, ontological,
interpretation, offers a framework with the novel feature that global
properties of quantum systems are reduced to local ones; but no conclusions
follow concerning information flow in more standard quantum mechanics.

Quantum Physics