  The psychiatrist Ian Marshall has offered a model that aims to explain the coherent unity of consciousness by appeal to the production within the brain of a physical state akin to that of a Bose-Einstein condensate. The latter is a quantum phenomenon in which a collection of atoms acts as a single coherent entity and the distinction between discrete atoms is lost. While brain states are not literally examples of Bose-Einstein condensates, reasons have been offered to show why brains are likely to give rise to states that are capable of exhibiting a similar coherence (Marshall and Zohar 1990).