# Quantum Reality, Perspectivalism and Covariance

## TL;DR

This paper explores how realist interpretations of quantum mechanics, especially perspectivalism, can address quantum contextuality and support relativistic covariance, advancing understanding of quantum properties beyond instrumentalist views.

## Contribution

It argues that perspectivalism arising from quantum contextuality is essential for reconciling realism with relativistic covariance in quantum theory.

## Key findings

- Perspectivalism naturally emerges from quantum contextuality.
- Perspectivalism is crucial for achieving relativistic covariance.
- Realist interpretations can incorporate non-classical indeterminacy in quantum properties.

## Abstract

Paul Busch has emphasized on various occasions the importance for physics of going beyond a merely instrumentalist view of quantum mechanics. Even if we cannot be sure that any particular realist interpretation describes the world as it actually is, the investigation of possible realist interpretations helps us to develop new physical ideas and better intuitions about the nature of physical objects at the micro level. In this spirit, Paul Busch himself pioneered the concept of ``unsharp quantum reality'', according to which there is an objective non-classical indeterminacy---a lack of sharpness---in the properties of individual quantum systems. We concur with Busch's motivation for investigating realist interpretations of quantum mechanics and with his willingness to move away from classical intuitions. In this article we try to take some further steps on this road. In particular, we pay attention to a number of \textit{prima facie} implausible and counter-intuitive aspects of realist interpretations of unitary quantum mechanics. We shall argue that from a realist viewpoint, quantum contextuality naturally leads to ``perspectivalism'' with respect to properties of spatially extended quantum systems, and that this perspectivalism is important for making relativistic covariance possible.