Remarks on the mind-body question

“Moreover, the proposed connection between consciousness and quantum measurement is almost opposite, in the Orch OR scheme, to the kind of idea that had frequently been put forward in the early days of quantum mechanics (see, for example Wigner [105]) which suggests that a ‘quantum measurement’ is something that occurs…”

“26 Consciousness-collapse interpretations of quantum mechanics have been put forward by Wigner (1961) ,”

“Indeed, a home localized in space and time - namely, the physical site of the agent who assigns it! By this method, one expels once and for all the fear that quantum mechanics leads to ”spooky action at a distance,” and expels as well any hint of a problem with ”Wigners friend” [17].”

“[1] Wigner, E.”

“[6] E.”

“nario, for example, (Wigner, 1961) rather than there having to be a mysterious collapse at some point, both agents involved simply ascribe different states to the system being measured.”

“, see [61,83–86]).”

“) A familiar way of making the measurement problem vivid is by appeal to a Wigner’s friend scenario (Wigner, 1961).”

“Wigner’s famous thought experiment [3] is a tale of two agents.”

“Wigner (1961) and von Neumann (1932/1955) further stipulated that the superposition continues in the device until the results are observed by a conscious human, that conscious observation “collapses the wave function.””

“That is, one has to revisit the measurement problem (and specifically the Wigner friend paradox [73, 79, 87–89]), but now with a complete relational quantum theory at hand, as proposed here, which contains both a perspective-neutral description and all the individual perspectives, a structure that was not available be…”

“Many physicists have interpreted the quantum–mechanical state in this way, for instance Wigner ( 6 ,7) and, recently, van Fraassen.”

“The occurrence and amount of rainfall are random inputs.4 The details are interesting, but for our purposes the point to remember is that the randomness of the rainfall input is important in explaining the robust structure of the dynamics of soil moisture.”

“Wigner [67] proposed an extension of this experiment, with two observers.”

“The notation is meant to suggest the setup of Wigner’s friend thought experiment [7].”

“, the quantum Zeno effect [34, 35], the delayed choice quantum eraser experiment [36–40], or the Wigner’s friend experiment [41, 42], among others) in which the ability to perform measurements and using the information of the outcomes to update the state is essential for their implementation.”

“One approach to drawing the distinction (between cases where collapse occurs and cases where no collapse occurs) that arguably avoids both of these pitfalls, and arguably does begin to smell like interpretation of the theory, is due to Wigner (1961).”

“The explicit quantum description of an observer is at the heart of the Wigner’s friend thought experiment [2].”

“(The only prominent exceptions are certain proposals for dynamical collapse models where the consciousness of the observer is implicated in the mechanism that leads to collapse [96, 97].”

“Wigner [7] considered a situation in which not he himself but his friend performs measurements of some quantum system to let him know the measurement result afterwards.”

“…the bizarreness of quantum mechanics and the lack of consensus about its interpretation, including the fact that some interpretations treat mentality as fundamental (such as the many minds view and some versions of the Copenhagen interpretation [Wigner 1961; Albert and Loewer 1988; Faye 2008]).”

“Darwin (1929) to E. Wigner (1979) , relied on a dualist view of the mind-body problem to provide the measurement problem with a dubious “solution”: the collapse of the wave-function by an act of conscious awareness.”

“In the 1960s, Wigner followed up on this proposal in [86] (in his later writings, he repudiated this point of view about the role of consciousness, stating that “it is outside the realm of quantum mechanics” [87]), coining the example of his now proverbial “Wigner’s friend.”

“(7) Wigner pointed out that only detection events are real (what you get is what you measure) and that the wave function is only a mathematical tool in order to calculate probabilities between a detection event and another.”

“This situation is illustrated by the gedankenexperiment of Wigner’s friend [4].”

“The original Wigner’s friend gedankenexperiment is a thought experiment first considered byWigner in 1961 [1] that highlights the tension between unitary evolution and measurement collapse in quantum theory.”

“The “Wigner’s friend” gedankenexperiment [80] assumes that different observers will agree on system identification but disagree on state ascriptions.”

“’ whenever thinking about the Author of [32]).”

“In the early 1960s, Wigner published two papers that would become the centerpiece of his views on the foundations of quantum mechanics.(31,32) He revisited a distinction first emphasized by von Neumann between two kinds of evolution of quantum states.”

“The distinction is exemplified in the Wigner’s friend thought experiment [2, 3].”

“The notion of measurement, in turn, is a highly nontrivial matter, as contemplations by Wigner [77], Wheeler [75], and Bell [3], among many others, show.”

“( 66 , 67) These avenues will not be pursued here as they do not seem to be the best way to progress towards developing a coherent theory of mathematics and physics.”

“expels once and for all the fear that quantum mechanics leads to “spooky action at a distance,” and expels as well any hint of a problem with “Wigner’s friend” [34].”

“The non-absoluteness theorems are descendants of the Wigner’s friend paradox[6], which describes a scenario in which some observer, Chidi, performs a measurement {|Si〉〈Si|} on a system S, and then another observer, Alice, performs a measurement on the joint system of Chidi and S.”

“The majority of the quantum community did not share Wigner’s viewpoint; for them physical measurement is terminated at the pointer of an apparatus. is operating with superpositions of alternatives.”

“But, in spite of the long tradition of this argument [18], there is as yet no direct scientific evidence for such a causal interaction between conscious mind and quantum-physical objects.”

“And this sense has also been regarded as important in all those interpretations in which human consciousness is explicitly invoked to solve the measurement problem [4,5].”

“to speculate as to whether a given intelligence has the “same types of impressions and sensations” [2] as our own.”

“Consider one of the common formulations of the measurement problem: Wigner’s friend (Wigner, 1961).”

“2.1 The scenario of Wigner=s Friend Wigner (1961) considered a hypothetical scenario in which his friend (whom I will call Alice) is confined to a physically isolated laboratory while performing a quantum measurement on a system (I=ll take this to be of the z-spin of a spin 2 atom initially…”

“Wigner (1961) was one of the first who suggested that quantum ffects (in particular – the collapse of the wave function) were assoiated with consciousness.”

“ing fundamental issues in quantum theory is not new [34,39].”

“…structure [49–51] (in which the pieces of apparatus locally have a well defined causal structure but in which no global causal structure exists between them) or extended Wigner’s friend scenarios [52–57] (in which the experimenters themselves are treated as part of the experimental scenario).”

“Our game is based on Wigner’s (1962) proof that another person is conscious by virtue of effects of their observa-”

“” Where does this irreversible observation take place? Since the physical laws (with the possible exception of the weak force) are time-reversible, the act of irreversible observation must, according to Wigner [96], occur in the consciousness, thereby violating quantum mechanics.”

“The argument proceeds by applying these assumptions in analysing a Gedankenexperiment obtained by extending the “Wigner’s friend” experiment described by Wigner in [16].”

“…may be proven wrong in the endgame, but the causal completeness of physics is not completely obvious given the state of today’s science (consider, e.g., consciousnesscollapse interpretations of quantum mechanics by Wigner 1961 and Stapp 1993)—though the burden is on the emergentist to show this.”

“The decoherence formalism establishes that this environment, not present in standard Wigner’s friend setups [1–4], determines to which states the memory of Wigner’s friend collapses, and therefore which outcomes are recorded by her.”

“Works on the role of consciousness in the quantum measurement process go back to von Neumann [1] and to Wigner [5].”

“Derivative off-shoots, such as Wigner and Stapp’s consciousness causes collapse interpretation [35,36] and Qbism [37,38], also postulate that consciousness is the fundamental quantum operator or actualizer of reality.”

“This aspect occurs again in the famous Wigner’s friend experiment, proposed by Eugene Wigner in 1961 to shed light on the quantum measurement process [21].”

“There have been attempts in the literature on quantum foundations to explain the apparent stability of the classical world from the perspective of quantum mechanics, and there is an example known as “Wigner’s friend” that deals with epistemic concerns in such attempts [Wig62].”

“According to some theorists [1, 2, 3, 4, 5, 6, 7, 8], consciousness is needed for making sense of quantum mechanics (QM).”

“The real Wigner [15] also argues, however, that if we would replace the friend with an inanimate measuring instrument, we would not prioritize the point of view of the instrument.”

“…analogies with other scenarios characterized by ambiguity, such as Ellsberg’s urn models (Ellsberg 1961), and explore inequivalent descriptions arising from different data observation levels in measurement settings, such as in Wigner’s Friend experiment (Wigner 1995; Frauchiger and Renner 2018).”

“Since the beginning of time (in about 1926) it has been argued that QM is about experience, knowledge, or information [16, 17, 18, 19], rather than about a free-standing reality capable of being described without reference to observers, their information, their interventions into “the course of Nature” [20], or their…”