Towards the end of 2011, Pusey, Barrett and Rudolph derived a theorem that aimed to show
that the quantum state must be ontic (a state of reality) in a broad class of realist approaches …

At a fundamental level, the classical picture of the world is dead, and has been dead now for
almost a century. Pinning down exactly which quantum phenomena are responsible for this …

Huw Price has proposed an argument that suggests a time symmetric ontology for quantum
theory must necessarily be retrocausal, ie it must involve influences that travel backwards in …

Quantum mechanics is an outstandingly successful description of nature, underpinning
fields from biology through chemistry to physics. At its heart is the quantum wavefunction, the …

According to our current conception of physics, any valid physical theory is supposed to
describe the objective evolution of a unique external world. However, this condition is …

We introduce a notion of contextuality for transformations in sequential contexts, distinct from
the Bell-Kochen-Specker and Spekkens notions of contextuality. Within a transformation …

The standard formulation of quantum theory assumes a predefined notion of time. This is a
major obstacle in the search for a quantum theory of gravity, where the causal structure of …

The status of the quantum state is perhaps the most controversial issue in the foundations of
quantum theory. Is it an epistemic state (state of knowledge) or an ontic state (state of …

A central question for causal inference is to decide whether a set of correlations fits a given
causal structure. In general, this decision problem is computationally infeasible and hence …

Abstract The Pusey–Barrett–Rudolph theorem has recently provoked a lot of discussion
regarding the reality of the quantum state. In this article we focus on a property called …