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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Consciousness causes collapse | 1/2 | https://en.wikipedia.org/wiki/Consciousness_causes_collapse | reference | science, encyclopedia | 2026-05-05T09:27:30.406153+00:00 | kb-cron |
The postulate that consciousness causes collapse is an interpretation of quantum mechanics in which consciousness is postulated to be the main mechanism behind the process of measurement in quantum mechanics. It is a historical interpretation of quantum mechanics that is largely discarded by modern physicists. The idea is attributed to Eugene Wigner who wrote about it in the 1960s, but traces of the idea appear as early as the 1930s. Wigner later rejected this interpretation in the 1970s and 1980s. This interpretation has been tied to the origin of pseudoscientific currents and New Age movements, specifically quantum mysticism.
== History ==
=== Earlier work === According to Werner Heisenberg’s recollections in Physics and Beyond, Niels Bohr is said to have rejected the necessity of a conscious observer in quantum mechanics as early as 1927. In his 1932 book Mathematical Foundations of Quantum Mechanics, John von Neumann argued that the mathematics of quantum mechanics allows the collapse of the wave function to be placed at any position in the causal chain from the measurement device to the "subjective perception" of the human observer. However von Neumann did not explicitly relate measurement with consciousness. In 1939, Fritz London and Edmond Bauer argued that the consciousness of the observer played an important role in measurement. However London wrote about consciousness in terms of philosophical phenomenology and not necessarily as a physical process.
=== Wigner's work === The idea that "consciousness causes collapse" is attributed to Eugene Wigner who first wrote about it in his 1961 article "Remarks on the mind-body question" and developed it further during the 1960s. Wigner reformulated the Schrödinger's cat thought experiment as Wigner's friend and proposed that the consciousness of an observer is the demarcation line that precipitates collapse of the wave function, independent of any realist interpretation. The mind is postulated to be non-physical and the only true measurement apparatus. The idea was criticized early by Abner Shimony in 1963 and by Hilary Putnam a year later. Wigner discarded the conscious collapse interpretation in the later 1970s. In a 1982 lecture, Wigner said that his early view of quantum mechanics should be criticized as solipsism. In 1984, he wrote that he was convinced out of it by the 1970 work of H. Dieter Zeh on quantum decoherence and macroscopic quantum phenomena.
=== After Wigner === The idea of consciousness causing collapse has been promoted and developed by Henry Stapp, a member of the Fundamental Fysiks Group, since 1993.
== Description ==
=== Measurement in standard quantum mechanics === In the orthodox Copenhagen interpretation, quantum mechanics predicts only the probabilities for different observed experimental outcomes. What constitutes an observer or a measurement is not directly specified by the theory, and the behavior of a system under measurement and observation is completely different from its usual behavior: the wavefunction that describes a system spreads out into an ever-larger superposition of different possible situations. However, during observation, the wavefunction describing the system collapses to one of several options. If there is no observation, this collapse does not occur, and none of the options ever become less likely. It can be predicted using quantum mechanics, absent a collapse postulate, that an observer observing a quantum superposition will turn into a superposition of different observers seeing different things. The observer will have a wavefunction which describes all the possible outcomes. Still, in actual experience, an observer never senses a superposition, but always senses that one of the outcomes has occurred with certainty. This apparent conflict between a wavefunction description and classical experience is called the problem of observation (see Measurement problem).
=== Consciousness-causes-collapse interpretation === This consciousness causes collapse interpretation has been summarized thus:
The rules of quantum mechanics are correct but there is only one system which may be treated with quantum mechanics, namely the entire material world. There exist external observers which cannot be treated within quantum mechanics, namely human (and perhaps animal) minds, which perform measurements on the brain causing wave function collapse.
Stapp has argued for the concept as follows:
From the point of view of the mathematics of quantum theory it makes no sense to treat a measuring device as intrinsically different from the collection of atomic constituents that make it up. A device is just another part of the physical universe... Moreover, the conscious thoughts of a human observer ought to be causally connected most directly and immediately to what is happening in his brain, not to what is happening out at some measuring device... Our bodies and brains thus become ... parts of the quantum mechanically described physical universe. Treating the entire physical universe in this unified way provides a conceptually simple and logically coherent theoretical foundation...
== Objections to the interpretation == Wigner shifted away from "consciousness causes collapse" in his later years. This was partly because he was embarrassed that "consciousness causes collapse" can lead to a kind of solipsism, but also because he decided that he had been wrong to try to apply quantum physics at the scale of everyday life (specifically, he rejected his initial idea of treating macroscopic objects as isolated systems). Bohr said circa 1927 that it "still makes no difference whether the observer is a man, an animal, or a piece of apparatus." This interpretation relies upon an interactionist form of dualism that is inconsistent with the materialism that is commonly used to understand the brain, and accepted by most scientists. (Materialism assumes that consciousness has no special role in relation to quantum mechanics.) The measurement problem notwithstanding, they point to a causal closure of physics, suggesting a problem with how consciousness and matter might interact, reminiscent of objections to Descartes' substance dualism.