Current concepts of delusion rely on the assumption that one single objective external reality exists as a benchmark for our internal experiences. With the advent of quantum theory this assumption has become untenable. Accepting the Copenhagen interpretation that there is no reality beyond what is revealed by the act of measurement or observation implies that there is no objective reality. One alternative interpretation of quantum theory is the “many worlds” interpretation which finds its philosophical correlate in the “plurality of worlds” theory. However, the idea of all possible worlds being not just possible but real is even more counter‐intuitive. Virtual reality is a way to systematically alter the usual relationship between external reality and the user’s experience of it. Although virtual reality is not the same as parallel reality and both are separate strands in the “fabric of reality” they are related. With the advance of virtual reality there is already developing an increasing sense that the real and digital worlds seem to converge. But even if we believed in only one single objective external reality we could still never experience this reality directly. Our experience of reality is essentially one of virtual reality as generated by our brain. The “many worlds” interpretation implies that other copies of our brain rendering other experiences exist. Thus, in view of the uncertain nature of reality it is necessary to rethink our accepted concept of psychosis. Currently, meticulous history taking and accurate clinical observation remains our best option trying to understand psychotic symptoms

delusion, DSM, many worlds interpretation, plurality of worlds, quantum theory, parallel reality, psychosis, virtual reality