**The Dead-Alive Physicist experiment****:**

**a case-study disproving the hypothesis that consciousness causes the wave-function collapse in the ****quantum mechanical measurement process****.**

** **

Carlo Roselli, independent researcher and deviser of the experiment; Via di Villa Ada 24, 00199 Roma (Italy), e-mail address: beswick@tiscali.it.

Bruno Raffaele Stella, co-author and corresponding author, prof. at Dipartimento di Fisica Università Roma Tre and INFN Roma Tre, retired; Via Santa Maria della Speranza 11, 00139 Roma (Italy); e-mail addresses: brunoraffaelestella@gmail.com and stella@desy.de; telephone: +39-3332753639; +39-0688642035, ORCID: 0000-0002-5729-8210.

* *

**Abstract. **The aim of this paper is to definitely falsify Wigner’s hypothesis that consciousness is necessary in the quantum measurement process. In order to achieve our target, we propose a variation of the *Schrödinger’s cat* thought experiment called “DAP”, short for “Dead-Alive Physicist”, in which a human being replaces the cat. The intuition of a specific strategy has enabled us to plan our experiment in such a way as to disprove, despite common expectations, the consistency of Wigner’s hypothesis and to oblige dualist supporters of this hypothesis either to be trapped in solipsism or to rely on an alternative interpretation of quantum mechanics in which a real world of phenomena is assumed to exist independently of our sensorial apparatus and mind, and where the role of the observer needs to be reconsidered. Our analysis hence provides support to a more intuitive concept of the relationship between the observer and the objects of experimental observation; this and a few other implications are discussed, respectively, in the fifth section and in the conclusions.

**Keywords**: the measurement problem in quantum mechanics, quantum mind-matter interaction, the von Neumann chain, quantum superposition of macroscopically distinguishable states, Schrödinger’s Cat, Wigner’s friend, observer’s consciousness, wave-function collapse.

** **

1** Introduction**

** **

The Copenhagen interpretation of quantum mechanics (QM) does not explain how measurements take place. This gives rise to some thought-provoking demonstrations usually called “paradoxes” (for example *Schrödinger’s Cat*)^{[1] }which render questionable the theory’s claim to completeness, unless one assumes that consciousness plays a fundamental implementation of the quantum measurement process.

Eugene P. Wigner (1902-1995), following the books published in 1932 and 1955 by the mathematician John von Neumann[1] (1903-1957) and a little book published in 1939 by the physicists Fritz London and Edmond Bauer^{[4]}, developed an argument in favour of the above assumption, giving rise to the thesis of the wave-function-collapse (WFC) at biological-mental level, here more simply called “idealistic interpretation of QM”.[2]

This paper proposes an innovative version of the *Schrödinger’s cat* and *Wigner’s friend* experiments with the purpose of disproving the consistency of the idealistic interpretation of QM, without taking into account, in our discussion, other well-known interpretations concerning the measurement problem.

We will use the term “idealistic” to refer to the Copenhagen [Niels Bohr (1905-1962)] view of atomic phenomena taken to the extreme. This view, in its turn, asserts that an elementary quantum system, say a photon or an electron, is in a state of intrinsic indeterminacy as long as it does not interact with a measuring apparatus. It also asserts that measurements can be made, but without providing an explicit definition of the boundary which separates quantum from classical worlds.[3]

This is the main problem with the theory which weakens its claim to *completeness.* Indeed, the Copenhagen interpretation is not the only possible interpretation of QM that is subject to this problem which, in more general terms, may be considered as that of defining a satisfactory boundary – and a satisfactory transition process – between micro-systems characterized by quantum state uncertainty and macro-systems obeying the deterministic laws of classical physics (inclusive of the deterministic chaos).[4]

Starting from the Copenhagen view, the idealistic interpretation assumes that it is the observer’s consciousness the fundamental factor which is able, in some unspecified and mysterious manner (Wigner refers to “a deus ex machina”),^{[12, p. 188]} to collapse the quantum system down into one only of its possible states. Here *consciousness* would play an active role in the measurement process, and would be the only factor capable of determining the transition from the ambiguous realm of potentials to the unequivocal realm of actual events. This is the kind of vision we mean when referring to the idealistic interpretation of QM.

By its very nature, this interpretation is difficult to evaluate, both in purely conceptual terms and, obviously, at the empirical-experimental level.[5]

The objective of the thought experiment which will be described hereafter is to demonstrate how such an interpretation, also known as “consciousness causes collapse hypothesis” (CCCH) of the wave function (WF), may be forced to conclusions that are incompatible with the assumption that consciousness is necessary for providing a complete explanation of quantum measurement process.

2** The DAP experiment **

** **

In this section we are going to propose a rather dramatic experiment, in which an audacious physicist named “**P**” is prepared to risk death.[6] Imagine **P **inside a sealed and dark room. In a sense,** P **will play the role of Schrödinger’s cat as well as the part of Wigner’s friend in the original experiments, but – as will be seen – he will have, in our view, a much more important role.

** On the ceiling of the room (figure 1) there is an apparatus, L,[7] programmed to emit at a precise time a photon propagating in a direction along which is located a beam splitter, BS, which forms with it an angle of 45°. Beyond the BS there are two photodetectors, D and D’ with 100% efficiency; D is located along the path of the incident photon, fixed on top of a box and connected to a hammer inside it; under the hammer there is a glass flask containing a lethal dose of gas called “LGD”; D’ is located along a path which is rotated by 90° with respect to the previous.**

The experiment is planned as follows:

- L will emit a photon at l2.00 AM hours;
**P**has deliberately narcotized himself one hour beforehand, at 11.00 AM, with a dose of a powerful narcotic, crucial for the experiment, called “**CPB**” (Conscious Perceptions Breaker)[8] and 100% guaranteed to induce a heavy coma-like sleep for two hours;- If D is activated, the
*hammer falls, shatters the flask,*the**LGD**is released and subsequently**P**will die.[9] - If D’ is activated,
**P**remains alive under the**CPB**‘s effect and will become conscious at 1:00 PM.

Let us now briefly consider how quantum theory describes the experimental system: the photon wave function collides with BS at 12:00 + Δ*t*_{1} PM (where Δ*t*_{1} is the photon travelling time from L to BS) and splits into two component parts, one corresponding to the photon having been transmitted (*T*) and the other to the photon having been reflected (*R*), both with a probability amplitude given by a modulus of a coefficient, which, in our example, is 1/Ö2, as shown hereafter:

The combination of these two parts evolves as a linear superposition according to the Schrödinger equation and travels along two different paths, until the instant in which, in agreement with the wave-packet reduction postulate based on the *Born rule*,[11] one presumes that a measurement process has occurred. This is the instant in which the WF collapses and one only of the possible alternatives becomes real, with probability given by the square of the associated modulus (hence, in our example, probability ½ for both alternatives).

If one assumes, as Wigner^{[10, pp. 181 and.187]}, “the existence of an *influence *of the consciousness on the physical world” and that “the measurement is not completed until a well-defined result enters our consciousness”, that is until the WF collapses into either one or the other of its two component parts, then inside the room, as long as **P** is under the **CPB**‘s effect, there is the* linear superposition* described above which, while time is passing, is propagating along the whole macroscopic measurement system up to the scale of **P**‘s brain. Then, the superposition will cease to be linear when it reaches **P**‘s consciousness.

Consequently, there are two possibilities or chains of events, which we call “*E*(∙)” and which will travel according to the superposition principle until a certain instant of the experiment:

*E*:_{T}*T*(transmitted part of the wave function), D registers and triggers the hammer, the flask is shattered, the**LGD**spreads in the room,**P**will be*dead*a few seconds after 12:00 AM.*E*:_{R}*R*(reflected part of the wave function), D’ registers, the hammer remains hooked, the flask intact,**P**will be*conscious*at1:00 PM.

**Fig**. **1** The experimental room in which **P** is under the **CPB**‘s effect from 11:00 AM; the Copenhagen interpretation of QM does not explicitly preclude a description of **P**, almost as well as Schrödinger’s cat, in a superposition of states ‘*dead’ *and ‘*alive-unconscious*‘ starting from a few seconds after 12:00 AM to just before 1:00 PM [see Eq. (2) in section 4].

It will be now important to analyze the DAP experiment from the perspective of Wigner’s argument concerning the essential role of the conscious observer. In particular, it is important to try to understand and establish when (at which exact point in time) it makes sense to say that a measurement has occurred. But first of all it will be useful to summarize Wigner’s argument based on his thought experiment known as “Wigner’s friend”, conceived to address the *observer-observed *question[12] which underlies the measurement problem in QM.

3** Some information pertaining ****Wigner’s friend experiment**

In his famous thought experiment, proposed as a reformulation of the *Schrödinger’s Cat* experiment, Wigner’s friend, here called “**F**”, is an experimental physicist left alone inside a laboratory with the task of checking *attentively* a detector and verifying whether or not it has emitted a flash, i.e. whether or not it has registered the arrival of a photon. Wigner suspects that **F**, as well as all other human beings, may be suffering from some sort of mental confusion (may have ambiguous perceptions) and could be in a superposition of states, i.e. |**F** perceives a flashñ + |**F** does not perceive a flashñ. Wigner, therefore, decides to contact him, say an hour after the photon has been emitted, in order to ask him whether or not he has perceived a flash. His reply (yes or no) should remove any doubt as to whether the wave-packet reduction has occurred. However, Wigner will question whether it is acceptable to establish that the collapse of **F **into one only of the two possible alternatives is determined by his action (i.e. by his request and reception of an unambiguous answer). He poses this question since his way of interpreting the state of the system gives rise to a rather embarrassing “paradox”, from which Wigner has three possible ways of escape:

- accept solipsism, in the sense that his mental and sensory faculties are different from those of his friend and from any other human being;
- assume that quantum mechanics is an incomplete theory;
- assume that quantum mechanics is not applicable to human beings.

Wigner refutes solipsism and, since he is a firm supporter of the *completeness *of QM, he opts decisively for the third solution, assuming that there are beings, at least human beings, endowed with *consciousness *that constitutes an ultimate reality and that determines the measurement processes by rules that are not susceptible to scientific description.

To this end, Wigner knows that an objective definition of the transition point from the weirdness of quantum world (characterized by states superposition) to our familiar and unequivocal classic world cannot be found, but he proposes to identify such a point within the von Neumann’s chain of the measurement apparatuses (see introduction, note 1). Thus he establishes, *believing that he may not be contradicted*, that *consciousness *represents the point of passage (between quantum and classical systems) which causes the collapse of the WF.

On the basis of these assumptions, Wigner considers himself justified to go further and develops his philosophical concept of reality centred around mind-matter duality and the dominant role of consciousness in our world.[13]

4** Formal description of the DAP experiment **

** **

** **All the few scientists[14] who (ignoring the present paper) are today adhering to the CCCH, will believe that *any* QM experiment (no matter whether applied to a cat or to a human being) should in the end give rise to the same conclusions drawn by Wigner from his thought experiment and from his additional and stronger hypothesis ^{[12, pp.185-196] }concerning the role of consciousness in the measurement process.

In discussing the DAP experiment described in section 2, we will put ourselves in Wigner’s place in order to verify whether or not there are the conditions for **P**‘s consciousness to bring about the WFC.

To this end, the entire experiment will be divided into two chronologically distinct phases, in each of which the wave function of the system, although including superposition of macroscopically distinguishable states, is not in confliction with the Copenhagen interpretation of QM and, therefore, it can be described as follows:

** **

4.1** Four remarks regarding the experiment**

** **

(i) – The expedient of the **CPB **has a fundamental function in this experiment; in fact, supposing that the **CPB **were not used, according to the idealistic interpretation of QM, **P**‘s consciousness would cause the collapse of the WF as soon as he became aware of whether he were bound to die or to survive.

(ii) – Both phases describe quantum superposition of macroscopically distinguishable states in sequence from detectors D and D’ to **P’**s brain. Note that in the first phase no information is available and no collapse takes place (unless an external observer enters the room before 1:00 PM).

(iii) – In the second phase (figure 2), again according to the idealistic interpretation, the collapse of the WF requires that one of its two branches be eliminated by someone’s conscious observation.

(iiii) – Human beings have access to their own internal states, perhaps similarly to cats or other animals, but, differently from these, they have the faculty of reasoning, drawing logical conclusions and making *verbal reports*, as in Wigner’s experiment, where his friend is attentive and can provide an answer when questioned about his experience; this last remark, even though not strictly relevant, will make sense in our description.

5** The DAP experiment disproves the consistency of the CCCH**

We shall refer to Eq. (3), which describes the *hypothetical* superposition of two macroscopically distinguishable states, |**P ***dead*ñ + |**P ***alive-conscious*ñ, and imagine that an external physicist named “**W**” (who is supposed to play the role of Wigner), wearing a gas mask as a precaution, decides to open the room, say at 1:30 PM, to check whether **P** is *dead *or *alive*:

– **1 ^{st}** possible outcome:

– **2 ^{nd}** possible outcome (see Figure 2):

**Fig. 2** As already pointed out in figure 1, **P** can be described in a superposition of states, ‘*dead’ *and *‘**alive*–*conscious’*. Yet, if an external physicist opens the room, he will certainly find **P**** **either *dead *or *alive*–*conscious* [see Eq. (3)].

However, P rejects **W**‘s conclusion as meaningless owing to the considerations that we are going to delineate hereafter.

Since Wigner is relying on a causal relationship between two phenomena, namely “the presence of consciousness” and “the WFC”, we will examine whether, in the context of our experiment, there is a logical way for ascertaining the former as a causal agent of the latter.

If we agree to the Copenhagen-Bohr interpretation of quantum mechanics (thus assuming it as a complete theory in which the question of the measurement is left unanswered) and take into account any kind of quantum physics experiments (in particular Schrödinger’s cat, Wigner’s friend or similar versions), it is evident that the experimenter, in order to acquire knowledge of the actual outcome, has to effectuate an *intentional *act of observation that, in Wigner’s idealistic interpretation of QM, is assumed to cause the collapse of the wave function. Moreover, according to Wigner’s CCCH, the measurement process takes place exactly when the impression of a *definite result* enters the observer’s consciousness^{[12, pp. 175-176]}.

Nonetheless, the above argumentation does not suit the DAP experiment simply because **P**, in view of the introduction of the **CPS**‘s strategy, plays an exclusive role never conceived before. In fact, **P**, if conscious at 1:00 PM, is neither in the same situation of the observer who *can* *decide* when to open Schrödinger’s box for verifying the state of the cat, nor in the same *status of attentiveness* of Wigner’s friend for checking whether or not he perceives a signal.

In our experiment, when examining the second possible outcome, **P**‘s conditions are radically different from those described above and his consciousness cannot be the cause of such an outcome for an evident reason: in the light of the cause-effect link hypothesized by Wigner (see introduction, note 2), **P**‘s consciousness should precede its own appearance at 1:00 PM. But clearly, owing to the **CPB**‘s effect, *his consciousness is not there before that time*.[15]

Indeed, the DAP experiment has been devised in such a way that what happens at 1:00 PM (when analyzing the second possible outcome) is *nothing more than the fortuitous appearance of consciousness in P‘s brain *(as soon as the

Once clarified this logical step, one can conclude that the collapse of the WF is not coinciding with one or the other of the two possible outcomes [(see next section, point (**c**)].

Before coming to our final conclusions, a preliminary remark seems appropriate: in the previous section, equations (2) and (3) are formulated with the same rules adopted in both Schrödinger’s cat and Wigner’s friend thought experiments, the first proposed as a means to *ridicule* the assumption that QM is a complete theory and, particularly, the idea of macroscopically distinct states in quantum superposition, the second devised with the aim at preserving its *completeness* (see section 3), while the DAP experiment vindicates Schrödinger’s view, thus corroborating the idea of QM *incompleteness*.

6 **Conclusions**

** **

All the above considerations have lead us to the logical conclusion that* the collapse of the wave function is independent of the observer’s consciousness *and that, therefore, the CCCH is unfounded despite a general conviction that such hypothesis is not falsifiable.[16]

If our analysis is accepted as well-grounded,[17] a supporter of the idealistic interpretation of QM, well represented by **W **in the DAP experiment, could still believe that it has been his consciousness to cause the collapse of the WF at 1:30 PM, no matter whether he found **P** dead or alive; but in this case he would be trapped in *solipsism*, already refuted by Wigner in his friend’s experiment.

Thus, starting from a rebuttal of solipsism as undesirable in science, one has to rely on an alternative interpretation of QM, in which the role of the conscious observer is merely reduced to acknowledge the experimental results. Straightaway we understand that these conclusions have further implications, such as:

(**a**) – the concepts of “random and unintentional self-observation” and “collapse of the WF independent of consciousness” emerge from the *logical structure* of our thought experiment (based on the **CPB**‘s strategy), since it allows to see in a new light the relationship between the observer and the object of his observation (as explained in section 5), a relationship which, in Wigner’s idealistic interpretation of QM, is assumed to be essential in tackling the measurement problem;

(**b**) – if it were not conceivable an experiment, such as the DAP, capable of disproving the CCCH, this hypothesis would still represent a possible and, for a few physicists (see note 14), even more suitable alternative to the wide range of different interpretations of quantum physics. __ __

(**c**) – in the realistic QM theories based on the collapse postulate, the boundary between quantum and non-quantum systems should be now reasonably *rescaled down* to the transition point between the quantum system [here given by the superposition of the two states of the photon, as shown in Eq. (1)], and the initial (uncertain number of) atomic components of the photo-detector (phototube) with which it interacts at 12:00 + Δ*t*_{2} PM (where Δ*t*_{2} is the travelling time of the photon WF from the source L to the photo-detectors D and D’);[18]

(**d**) – in the collapse theories *Schrödinger’s cat *experiment cannot be thought any longer as a paradox: before opening the box, the cat (as well as **P **in the DAP experiment) is in a statistical mixture of states, ‘dead’ or ‘alive’;

(**e**) – the falsification of the CCCH rules out also the hypothesis that the collapse of all the wave-functions involved in our Universe (according to the hypothesis shared by many scientists that consciousness is regarded as an emergent phenomenon) occurred when the first conscious being appeared in it;[19]

(**f**) – the** CPB**‘s strategy adopted in our experiment can also be applied to cases in which consciousness is present in both branches of the wave function, as described in Wigner’s friend experiment. We leave the analysis of this specific issue to further research.

In synthesis, the starting point of our work is that the idealistic interpretation requires, on one hand, the presence of superposition of macroscopically distinct states and, on the other hand, the conscious perceptive faculty of the observer. This is necessary for consciousness to play a fundamental role in the collapse of the wave-function. Nevertheless, it is possible to devise at least a thought experiment (e.g. our DAP), which disproves the hypothesis that it is the observer’s consciousness to cause the WF-collapse. If this is shared as logically compelling, then one is left with the immediate issue of what the best alternative to the idealistic interpretation should be,[20] and clearly this is an entirely different (and daunting) problem. However, we feel that the ordinary idea behind our experiment is that there are two ingredients, given by the *wave function* and the *conscious state* of potential observers, which cannot in general be clearly separated, at least in such a way as to make the latter a causal agent in the collapse of the former. If this is true, then a fruitful way to tackle the measurement problem can only be one that treats the above two ingredients in a single coherent framework. Recent advances in the quantum de-coherence and a re-examination of Everett’s Many Worlds Interpretation[21] suggest that such a framework could be constructed entirely within the boundaries of the theory itself,[22] but clearly this is not the only route.

Furthermore, the DAP experiment could represent a good reason for strengthening some of the actual quantum mechanical spontaneous localization models, where observers have no particular role: we are referring to Ghirardi, Rimini and Weber theory^{[18] }(GRW) and to Penrose^{[23, pp. 83-92] } and to Hameroff and Penrose^{[24] }interpretations, in which the WF is assumed to be as a physical reality and its collapse as an objective dynamical process, that in Penrose’s approach is supposed to be induced by gravity.

We would like to close this paper quoting the following words of Steven Weinberg^{[42, p. 124]}, with which we fully agree:

I read a good deal of what had been written by physicists who had worried deeply about the foundations of quantum mechanics, but I felt some uneasiness at not being able to settle on any of their interpretations of quantum mechanics that seemed to me entirely satisfactory.

__ __

__ __

**Acknowledgments**

Our special gratitude goes to the late Professor Giancarlo Ghirardi for having devoted his time in reading and criticizing our earlier versions of the paper. His qualified and rigorous remarks have been fundamental for rewriting this final version. We are grateful to Professor Carlo Rovelli for having discussed with us some relevant issues pertaining the QM collapse theories, and for his useful suggestions concerning the role of conscious observer in our experiment. We like to thank Professor Enrico Marchetti (Università degli Studi di Napoli Parthenope) and Professor Lorenzo Stella (Università di Roma 2) for having debated with us some crucial details of the paper. Finally, we like to thank Susan Beswick for her scrupulous control of the English language of the text.-

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[1] In his book, von Neumann^{[2-3] }takes into consideration a causal sequence of macroscopic systems, the so called “von Neumann’s chain”, each of which observes the preceding one; at one end of the chain there is the quantum system followed by a first measuring device, while at the other end there is the consciousness of the observer; the link which precedes consciousness is made up of cerebral microstructures and the link preceding these is made up of various organs which are sensitive to external stimuli. Thus, arguing that quantum mechanics doesn’t provide any explicit indication of where the collapse of the wave-function may occur, von Neumann can legitimately assert that it can take place at any level of the chain.

[2] There are two main theses arguing that consciousness and quantum mechanical measurement are connected to each other in a *cause-effect relationship;* one thesis (Wigner) holds that the observer’s consciousness causes the collapse of the wave function, while the other thesis aims at demonstrating the opposite, i.e. that consciousness emerges from the so called “Orchestrated Objective Reduction”^{[22-23]}.

[3] The Copenhagen Interpretation, starting from a positivist conception of reality (the idea concerning the non-existence of quantities that cannot be measured), came to be interlaced with subjectivism, assuming that atomic systems are just mere possibilities and that they can achieve real existence only upon measurement/observation. In this view, only the acts of measurement/observation are real. Bohr’s work maintains that the theory is *complete *and that its principles do not legitimate us to ascribe well-defined properties to atomic systems until they have been measured. This implies the denial of the “principle of reality” of nature or, in other words, the real existence of phenomena independently of measurement procedures. In fact Bohr was convinced that there was no need for additional assumptions, believing that an objective conception of reality is not essential to physics.

[4] This is a well-known point of view in the historical debate on the nature of QM. Among the first and most illustrious physicists to uphold this position (or a very similar one) were von Neumann and Wigner. From the 1940’s onwards the problem of measurement has been at the centre of a lively scientific-philosophical debate: A. Einstein^{[5]}; D. Bohm^{[6-7]}; H. Everett^{[8]}; J.A. Wheeler^{[9]}; E.P. Wigner^{[10-12]}; S. Kochen and E.P. Specker^{[13]}; B.S. DeWitt^{[14]}; W.H.Zurek^{[15-16]}; D. Bohm and B. Hiley^{[17]}; G.C. Ghirardi, A. Rimini and T. Weber^{[18]}; G.C. Ghirardi, R. Grassi, P. Pearle, ^{[19]}; R. Penrose^{[20-22]}; S. *Hameroff*.and R. *Penrose*^{[23]}*;* D.Z. Albert^{[24]}; H.P. Stapp^{[25]}; M. Gell-Mann and J. Hartle^{[26]}; C. Rovelli^{[27]}; M. Tegmark^{[28]}; S. Haroche^{[29]}; A. Bassi, G.C. Ghirardi^{[30]}; G.C. Ghirardi^{[31]} ; J.S. Bell^{[32]}; S. Yu, D. Nikolic^{[33]}, and others. The debate on this subject has given rise to endless discussions and, so far, there has been a lack of consensus regarding which interpretation might be correct.

[5] Actually, neither von Neumann nor Wigner ever explained how something, namely consciousness, that seems to transcend the physical laws, can influence the physical world, e.g. causing the wave-function collapse.

[6] We obviously assume that he volunteered to do this experiment.

[7] In such a mechanism a battery is supplying electric power.

[8] It is our conviction that the introduction of such a strategy in the DAP experiment is the only possible way to falsify the CCCH.

[9] The **LGD** is assumed to allow **P** the passage from life to death without being aware of it (this assumption is concerning what we imagine as a legitimate **P**‘s personal request, while it is not fundamental for achieving our target).

[10] The factor i (which stands for √-1) represents a wave rotation of π/2 corresponding to a phase shift of ¼ of its wavelength and is here a mere formality (it is useful to describe some experimental set-ups such as Mach-Zehnder interferometer).

[11] This rule, introduced by Max Born in 1926, states that in quantum mechanics experiments the probability of obtaining any possible measurement outcome is equal to the square of the corresponding probability amplitude..

[12] The *observer-observed* distinction, while arbitrary, is necessary for the formulation of the theory, with the assertions always being of the type “an observer has made a particular observation” and never “a particular observable is like this or that”.

[13] An ontological dualism is therefore emerging from Wigner’s proposal: on one side, a *physical reality* inhabited by wave functions and, on the other side, the *consciousness* of each person; in accordance with the universal symmetry Principle, consciousness plays a primary role, since it has the power of causing the wave-functions collapse. This epistemological position is referred to the first Wigner who, however, in his final years changed his position for two main motivations: on one hand 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), on the other hand, because he was embarrassed arguing that “consciousness causes collapse” can easily lead to a kind of solipsism,

[14] See for example “A Snapshot of Foundational Attitudes Toward Quantum Mechanics**“, **Maximilian Schlosshauer, Johannes Kofler, Anton Zeilinger, arXiv:1301.1069** [quant-ph]**, (submitted on 6 Jan 2013).

[15] We can come to the same conclusion following a slightly different line of reasoning: Would it make sense that **P** decides to look inside the box to ascertain the state of the hammer and the flask? Certainly not, because he cannot find the flask shattered. In fact, since **P** had the chance to appear alive-conscious before taking this possible decision, he is intelligent enough to avoid it and to deduce that the WF collapse should have occurred long before independently of his consciousness, i.e. when the photon wave function interacted with the detector D’.

[16] Indeed, there are a few works on this subject which have been proposed and published in science reviews, but later criticized as inappropriate for disproving the CCCH. See for example J. Acacio de Barros and Gary Oas^{[34]}.

[17] We think that the validity of our argument is tenable with regard to at least one central hypothesis: the fact that the *conscious perception* phenomenon could, in certain controlled circumstances, be suspended in a human subject. In other words, there could be a time lapse during which the subject is totally deprived of the *faculty to consciously receive information* from external surroundings, and after which he will reacquire this faculty. While this assertion may probably be open to doubt from a philosophical point of view, it appears sufficiently backed-up by common sense (and maybe also by certain experiential data).

[18] As is well known, one only of the two detectors will register the arrival of the photon.

[19] We do not find reasonable that the phenomenon of consciousness in human beings or animals could have appeared at a precise instant of their evolution. According to some monistic conceptions of reality based on the assumption of pan-experientialism, a long chain of micro and macro-experiential phenomena should have occurred before reaching the complexity of the human mind. One of us (C. R.), in line with his monistic view of the world, affords the so-called “hard problem of consciousness”. Discussing the ideas of Thomas Nagel^{[35] }and David Chalmers^{[36]}, he debates this problem in another (yet unpublished) work, *Consciousness, proto-phenomenal experience and self-organization of atomic systems*, in which he proposes a curious solution by means of viewable topological dynamics.

[20] Once disproved the CCCH and refuted solipsism, the idea that the physical world exists independently of consciousness gives rise to a wide range of (unsatisfactory) conceptions of reality based on different forms of dualism, holism or monism.

[21] Hugh Everett^{[8]}, after having attacked the Copenhagen formulation of quantum mechanics and the von Neumann-Dirac theory, since neither the first nor the second provided an adequate and coherent solution to the measurement problem (owing to their subjectivism and to the linear evolution of the Schrödinger equation), proposed to replace them with pure wave mechanics, which he described as the standard theory, but eliminating from it the collapse dynamics postulate.

[22] See, for instance, Roland Omnès (2004)^{[37]}, Maximilian Schlosshauer (2007)^{[38 ]} and David Wallace^{[39]}; see also Bernard d’Espagnat^{[40]} and the very recent works of Art Hobson^{[41]}.

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