Quantum models of the mind: are they compatible with environment decoherence?

Quantum models of the mind propose that consciousness arises from coherent quantum states in the brain. This paper critiques the Hameroff-Penrose model, which relies on gravitational collapse orchestrated objective reduction (OOR), arguing instead that decoherence from environmental interaction is the more plausible mechanism. The authors conclude that the Hameroff-Penrose model is incompatible with decoherence, but a quantum brain remains viable if gravitational collapse OOR is replaced by decoherence. They disagree with Tegmark's conclusion that decoherence time calculations refute both the Hameroff-Penrose model and the quantum brain entirely, and also take issue with some points in Hagan, Hameroff, and Tuszynski's response to Tegmark.

Study at a glance

Abstract

Quantum models of the mind associate consciousness with coherent superposition of states in the brain. Some authors consider consciousness to be the result of a kind of internal quantum measurement process in the brain. In this paper we discuss the ideas of Hameroff-Penrose and Tegmark and their calculation for an estimate of decoherence time. We criticize the Hameroff-Penrose model in the context of a quantum brain model by gravitational collapse orchestrated objective reduction (OOR), assumed by Penrose, and we propose instead that the decoherence process is caused by interaction with the environment. We consider it useful to exploit this possibility because of the growing importance of the decoherence theory in quantum measurement, and also because quantum mechanics can be applied to brain study independently of the Hameroff-Penrose model for mind and consciousness. Our conclusion is that the Hameroff-Penrose model is not compatible with decoherence, but nevertheless the quantum brain can still be considered if we replace gravitational collapse OOR with decoherence. However, our result does not agree with Tegmark's conclusion of refuting not only the Hameroff-Penrose gravitational collapse but also the quantum brain, based on decoherence time calculations in specific cases in the brain. In spite of this fact we also disagree with some points of the response to Tegmark's article given by Hagan, Hameroff, and Tuszynski.