A quantum of consciousness

THE controversial idea that quantum effects in the brain can explain consciousness has passed a key test. Experiments show that anaesthetic drugs reduce how long tiny structures found in brain cells can sustain suspected quantum excitations. Because anaesthetic switches consciousness on and off, the results may imply that these structures, called microtubules, are a nexus of our conscious experience. According to some interpretations of quantum mechanics, a system can exist in multiple states simultaneously until the act of observing it distils the cloud of possibilities into a definite reality. Orchestrated objective reduction (Orch OR) theory postulates that brain microtubules are the place where gravitational instabilities in the structure of space-time break the delicate quantum superposition between particles, and this gives rise to consciousness. Physicist Roger Penrose and anaesthesiologist Stuart Hameroff proposed Orch…