The paper “Decoherence implies information gain”, co-authored by Dorje Brody and Lane Hughston (Goldsmiths University of London) has been published this week in Physical Review Research. In the literature, quantum decoherence — a phenomenon that captures the emergence of classical world from the underlying quantum — is understood to represent the loss of information from a quantum system into its environment. In this paper, it is shown that in fact the opposite is happening. Specifically, it is proved here that whenever a quantum system gains information from its environment, this necessarily leads to decoherence, and conversely that whenever a quantum system decoders, there is necessarily a net gain of information from its environment into the system. The paper is available open access (link here).