Wigner's Frame

TL;DR

This paper explores how reference frames and symmetries can clarify the interpretation of Wigner's Friend scenarios, proposing that some facts are frame-dependent while others are absolute, challenging the idea of a regress in relativization.

Contribution

It introduces a symmetry-based approach to distinguish between relative and absolute properties in quantum reference frames, offering new insights into quantum measurement scenarios.

Findings

Not all facts about observers' observations are frame-independent.

There may not be a joint distribution over outcomes that aligns with quantum predictions.

The approach argues against an infinite regress of relativization in quantum reference frames.

Abstract

This article suggests that thinking about the role of reference frames can provide new insight into Extended Wigner's Friend scenarios. This involves appealing to symmetries to make a principled distinction between properties of a system which are meaningful only relative to an external reference system and properties which are meaningful without further relativization. Thus we may propose that there are always well-defined facts about what observers have observed, but there are not necessarily well-defined facts about the relations between their reference frames, so there will not always exist a joint distribution over their outcomes which can meaningfully be compared to the predictions of quantum mechanics. In addition, this approach also offers a general argument against the idea that there should be a regress of relativization.