Dean Radin's Double Slit Experiments

#3
I still want to go over the paper a bit more, but here are a few things that occurred to me as I was re-reading it .

It would be interesting to do a controlled study where the participants were not told about the double slit part but rather, using the same protocols, were told to concentrate intently on something else.

Also, I note that in some of the experiments the controls were done without someone present during the double slit. I know Radin looked somewhat in one of them at the body heat issue, but I'm not sure if it coverred this issue (have to re-read it): The control perhaps should be done with someone sitting in the same spot as the subjects, but not given any instructions at all, nor told about the double slit aspect.

Did the paper state whether whoever calculated the results was blind or not to whether they were analyzing a control or subject line?

I don't know if it would make a difference or not, but I believe ideally controls should be identical to the subject experiment with the exception of the control variable.

Found it interesting that in the experiment where this was done (the retro-causal one) the overall effect size for controls and subject were identical at -0.13. It was only when the meditators were selected out that the significant effect was found.

The meditator angle is interesting as well, and one possibility came to mind related to the control I suggested above. Is it possible that thinking, in addition to being consciously experienced by us, sends out some physical stuff (waves? fields? I have no idea what the correct technical term should be) that did affect the output (whether intentional or not). It would be interesting to perform the experiment with the subjects at different distances (the one distance experiment he did in this paper showed no effect but Radin noted some possible technical defects as well so we should discount these results).

I have a question about the lag calculations. I couldn't tell from reading it, but did they provide a lag calculation for the inattention ones as well? (ie: there would presumably be a delay in them stopping concentrating as well.) I guess it would be quicker to stop thinking than to start thinking. That said, I wonder why the calculation is needed at all? Presumably the lag issue should affect trials in a similar manner, and therefore should not affect the results? I'm curious as to whether the results would be different without the lag adjustment?
 
#6
...

It would be interesting to do a controlled study where the participants were not told about the double slit part but rather, using the same protocols, were told to concentrate intently on something else.

...
Is it known if there are any other situations where there has been noticed such a consciousness interaction? They need something to measure.
 
#9
http://www.danko-nikolic.com/wp-con...kolic-Qm-and-consciousness-Annalen-Physik.pdf

This paper claims that the conscious collapse model has already been falsified. These are my observations regarding this paper:

Yu & Nikolic said:
Specifically, we expect to find an interference pattern at D0 in the following conditions:

i) No actual attempt to measure the “which-path” information was made, that is, D1 and D2 are not
implemented at all.

ii) The “which-path” information was measured as D1 and D2 are implemented in order to interact
with the incoming photons. However, no results were recorded by a macroscopic device and hence are not
visible or accessible to a human observer in any way.
Later, they state the following regarding these conditions:


Yu & Nikolic said:
The experimental results that falsify predictions i) and ii) already exist. Firstly, in experiments similar to that proposed here (e.g., [11, 20, 33]), it was shown that if “which-path” information was in principle obtainable, then even though no actual attempt was made to extract this information (i.e., to measure it), no interference pattern was found. For example, in the experiment carried out by Zou et al. [33], the interference pattern formed by the signal photons could only be observed when the paths of idler photons were aligned, i.e., the “which-path” information was destroyed. If the idlers were misaligned to allow the source of the signal photons to become distinguishable, the interference pattern disappeared. Interestingly, under such conditions, it is not important whether a detector is actually in place ready to make the measurement of “which-path” or not. As long as such measurement could be made, i.e., the photon path is in principle identifiable, the interference is wiped out [33]. Thus, the first prediction of consciousness hypothesis is false.

Secondly, in another set of experiments, “which-path” information was measured but was not recorded by a macroscopic device and, therefore, was not accessible to a conscious observer. Under such conditions, also no interference pattern was found. For example, in the experiments reported by Eichmann et al. [34] and D¨urr et al. [35], the “which-path” information was only stored in the state of a single atom. Results demonstrated unambiguously that even if such microscopically stored information was not actually read out, the mere fact that it could be read out ensured the absence of the interference pattern. Therefore, the existing evidence indicates that the second prediction is also false. (note: emphasis added)
I am still trying to source the experiments mentioned in the first scenario, however it seems that both scenario one and two both have to do with state vector reduction, not state vector collapse. State vector reduction is decoherence, where possible paths are reduced through an interaction with the environment (or measuring devices). State vector collapse is the realization of only one final outcome.

In my opinion, the authors have not really understood the concept of von Neumann chains in the von Neumann interpretation. For some reason, the authors felt that the experiment ended with the device itself, where the von Neumann chains would end in the conscious observation. It should be rather obvious that both scenarios still end in conscious observation, and that in the von Neumann interpretation, there exists a von Neumann chain until conscious observation.

To narrow it down, in the scenario involving a gain of which-path information, the interference pattern disappears, resulting in a diffraction pattern. This is the outcome that was collapsed by conscious observation. Remember that in the von Neumann interpretation, the conscious observation creates the history. The von Neumann chain collapses upon conscious observation, which could be a collapse to view the outcome of an experiment in which the which-path information is gained, which eliminates the interference pattern. By attempting to gain which-path information, this limits the possible paths that the photons can take, thereby eliminating the possibility of the wavefunction travelling both routes. The end observation creates the history that is consistent with the experimental conditions. The history doesn't "happen," rather, it is created based on the conscious observation. The Wheeler delayed-choice experiment supports this idea.

So I beg to differ with the authors that the concept of von Neumann Chains and conscious collapse within the von Neumann interpretation has been falsified. The authors use very strong language stating that "the existing experiments suggest clear conclusions," and that "all predictions have been falsified." It should be noted, especially regarding this latter comment, that the third predicted scenario has not been tested, as the authors themselves stated: "To the best of our knowledge, no direct attempt was made to test the third prediction." They followed this comment with the statement that "However, the expectations for such experiment are clearly set by the evidence related to predictions i) and ii)." However, these purported conclusions are based on erroneous notions of von Neumann Chains and the von Neumann interpretation.
 
#10
Let me explain this a little differently that might demonstrate my point.

The authors appear to believe that in the von Neumann interpretation that consciousness needs to directly observe the particles. This is beyond absurd, because if this were needed, we could never use computers or any device relying on quantum processes, since we were not opening the devices up to "observe" what the particles were doing in order to collapse the wave function. Instead, we sit down in front of the computer and observe the outcome of all the processes.
 
#11
Under, "A Physicist Investigates," we have some interesting commentary:

I mentioned that one way of achieving a positive result in this test is by exerting some physical force on the apparatus. A physicist or engineer would test this directly by having people try to exert that force on a force sensor of some kind. Obviously, parapsychologists don’t do it that way. It fails to show what they know to be true.
This is odd, since from what I can gather, most parapsychologists do not see this phenomenon as an undiscovered force. As I suggest, perhaps it has to do with insertion or extraction of quantum information from the system, which does not involve any force and would not require any transfer of energy.

One answer to that is abandoning careful experiments and simply argue that some feat can’t possibly have been a trick because they surely would have noticed. Parapsychologists apparently do not suffer from the same limitations to perceptions as the rest of us. Or perhaps of a few more inabilities to see something.

The other answer is to conduct experiments involving randomness, like the RNGs of PEAR or radioactive decay or something as simple as die. These experiments seem much less silly than any argument for the genuineness of something that looks like a magic trick.
But are they really? Why not measure the effect directly?

Why is there always randomness involved?

An obvious answer is that the “effect” is simply the result of data mining. My take on that here.
Here he is again critical, but critical the position that this PK is some sort of undiscovered force. This, again, is not what most parapsychologists think, and the reason randomness is involved is that if PK involves an insertion of extraction of information from the quantum system, the effects would be best seen in labile random systems. That's why randomness is involved.

But, since I aim to deliver the whole truth, I must also tell you that parapsychologists also have ideas on the issue. One idea that Ibison mentions in the mentioned article is that maybe experimenters can see into the future and somehow know, subconsciously, when to start an experimental run so that the purely random processes will deliver a favorable result. Ibison is quite open with the fact that the apparatus was basically just generating random numbers and not necessarily measuring anything.
This is the Decision Augmentation Theory, which does not fit all the data (such as from the global consciousness project).

While Jeffers completely failed to find anything in his 74 sessions, Ibison of the PEAR lab reported a “significant” result with only 20. Some will say that the latter experiment had a positive result.
Since I have most of the published issues of the Journal of Scientific Exploration that this was published in, I will have to try to find the actual paper. The concern I have here is first off, the actual data analysis itself and what the actual results were. Since analysis can be twisted one way or the other, I cannot comment regarding the actual results. However, it seems that Radin has discovered at least one factor that can affect the outcome of these experiments, which is that meditators are better. Perhaps this could be for the very simple reason that they are better able to focus on the experiment to elicit the desired outcome.

Considering a variable like this, and we know other variables in psi research play a role (ex: sheep-goat effect), what role might this play in seeing different results from different labs? The automatic suspicion from physicists is that this indicates that there is no effect, but this is because physicists are not used to dealing with experiments involving human performance and psychology. This may sound like a cop-out, but given the patterns seen in databases such as the ganzfeld, and the confirmed predictions of associations with the Myers-Briggs personality tests, I think that these may be legitimate concerns that need to be addressed in the experimental design.
 
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#12
Under "Radin for a Rerun" we find the following quip:

In 2008, Dean Radin published an article in Explore, The Journal of Science & Healing, a journal dedicated to alternative medicine. That’s certainly a good way to hide it from anyone who knows or cares about physics. Or ethics.
Dean Radin is currently coeditor-in-chief.
I find this to be an incredibly irritating and ignorant comment. New journals can be created because of the dogmatism of other journals within a field, not just because they want to hide their results from the mainstream. For example, the biologist Galton published a paper in the Royal Society in 1901 which applied statistics to a biological problem, but before the paper was published, he received a request from the Royal Society to keep math separate from biology. He then resigned from the Royal Society and then founded the journal of Biometrika so that there could be a journal that would explore mathematics as applied to biology. Now this doesn't make Radin correct, but the insinuation that he is wrong because it is not a mainstream journal is rather fallacious.

And what is the comment about ethics? He is not explicit, but I think implicit in this comment is the view that "alternative medicine" is all bunk and therefore unethical since it is doing nothing to help people that should be getting conventional treatment. I am not going to go into detail on this one, since nutrition is another of my passions and I don't even want to get started on the garbage that is in mainstream medicine and nutrition journals, but suffice it to say that this is a very ignorant comment.
 
#13
Also in "Radin for a Rerun" we find this:

The title of the paper, Testing Nonlocal Observation as a Source of Intuitive Knowledge, tells us that Radin sees this as relevant to intuition. Intuition, as he points out, is regarded as an important source of artistic inspiration or for scientific insights. It’s a bit hard to see what the connection between that and casting shadows should be. But remember that Radin doesn’t know what he is doing. He believes this is like Jeffers’ original design.
Radin doesn't know what he is doing? This is rather ironic since the author obviously doesn't know what he is talking about with respect to the concept of intuitive perception and how it relates to the double-slit or Michaelson interferometer experiments. The intuitive perception is of a direct, non-local perception of something in the environment, again perhaps some sort of insertion or extraction of information from the quantum system. Creativity in art and science (for scientific insight) is thought to be related to intuition, and this same intuition that we can also see in mathematical understanding has a strange aspect to it that some (like Kurt Gödel) have even linked to a transcendent platonic realm. What is this intuition? How can we intuitively know things like in mathematics? Can we intuitively know other things? That's what Radin is testing.

Radin is also highly educated (BSEE degree in electrical engineering, magna cum laude with honors in physics, from the University of Massachusetts, Amherst, and then an MS in electrical engineering and a PhD in psychology from the University of Illinois) and has worked with many reputable companies (AT&T Bell Labs, Stanford Research Institute), universities (Princeton, University of Edinburgh, University of Nevada), and been involved with government programs as well. This doesn't make him right, but it isn't the case that Radin just "doesn't know what he is doing."

His first error is in thinking that the original design could that someone gains knowledge about the photons’ paths. Learn why not in this post. This is a simple misunderstanding and easy to follow.
So what does this author think that the design was testing? Is he going back to the erroneous idea of some undiscovered force at work here? The "intuitive perception" is about gaining knowledge about the photons path, which, as this hypothesis would say, is about extracting quantum information from the system directly.

His second error is more weird and more typically parapsychological. He thinks that, if people can gain knowledge about the paths of a few photons in some unknown way, then it’s reasonable to assume that they can gain any knowledge via the same unknown mechanism.
We detect photons all the time with our eyes, and much more effectively. If that doesn’t tell us anything about intuition, then why should this?
Dean Radin is well aware of the government remote viewing programs, and in these programs, there is a similar concept, where the viewer could gain knowledge about a location by asking the right questions and allowing their "intuitive perception" to occur. In fact, it was so odd that project SCANATE asked the viewers to find out about a location given only coordinates. The author should be careful to denigrate out of ignorance. The comment about photons and the eyes is simply further magnifying the extent of the authors ignorance regarding the subject he is attempting to comment upon.
 
#14
In any case, temperature indeed seemed to increase slightly. Why the same temperature measurements were not conducted in the other experiments, or why the possible temperature influence was not investigated further, is unclear to me. They believe this should work, so why don’t they continue with it?
Because when he tested the idea of someone being in the room affecting the temperature, he found that it did, but that by itself did not affect the outcome. What was there to continue?

That means, that if there is a real effect in Radin’s paper, it is tiny. So tiny that it can’t be properly seen with the equipment they used.
There shouldn't be ANY effect. So what if it's tiny?

The “positive” result that he reports suffer from the same problem as virtually all positive results in parapsychology and also many in certain recognized scientific disciplines. It may simply be due to kinks in the social science methodology employed.
Some of the weirdness in the paper, not all of which I mentioned, leaves me with no confidence that there is more than “flexible methods” going on here.
The linked paper cannot explain all the positive results in parapsychology, and the blanket rejection of "virtually all positive results in parapsychology" as possibly being due to this paper demonstrates the authors ignorance on the parapsychological literature and all of the testing and confirmation done by statisticians and other analysts outside of the field. With this type of horrible assessment, this leaves me with no confidence of the author's credibility.

Radin believes that a positive result supports “consciousness causes collapse”. He bemoans a lack of experimental tests of that idea and attributes it, quite without justification, to a “taboo” against including consciousness in physics.
Thousands upon thousands of physicists and many times more students have out of some desire to conform simply refused to do some simple and obvious experiment. I think it says a lot about Radin and the company he keeps that he has no problem believing that.
I don’t know about you, my dear readers, but when I am in such a situation would have thought differently. Either all those people who should know more about the subject than me have their heads up their behinds. Or maybe it is just me. And I would have wondered if there was maybe something I am missing. And I would have found out what it was and avoided making an ass of myself. Then again, I would have (and have) also avoided book deals and the adoration of many fans and the like, all of which Radin secured for himself.
So who’s to say that reasonable thinking is actually the same as sensible thinking.

But back to the physics. As is obvious when one manages to find the relevant literature, conscious awareness of any information is not necessary to affect an interference pattern. Moreover, wave function collapse is not necessary to explain this. Both of this should be plain from the mainstream paper mentioned here.
The author has presented a paper that I commented on earlier, and it certainly does not falsify the idea of conscious collapse in the von Neumann interpretation as he suggested here:

It has also been argued that this view is incompatible with experimental evidence. Though I think most physicist would rather regard the view as being unfalsifiable philosophy.
Although his comment is rather confusing, because on the one hand he is presenting a paper that claims to empirically falsify conscious collapse of von Neumann, but in the next sentence say that he thinks most physicists would consider conscious collapse as unfalsifiable philosophy. Which is it?

Besides, the comment "Radin believes that a positive result supports “consciousness causes collapse”" is clearly not reflected in Radin's paper, where he states the following:

Dean Radin said:
What the present experiments do not unambiguously demonstrate is that the observed effects are necessarily relevant to the QMP [Quantum Measurement Problem]. That is, what we observe was a decline in interference correlated with periods of observation versus no-observation. This is consistent with a consciousness-related interpretation of the QMP, but there may be other ways of explaining these effects that do not require quantum concepts.
Yeah, that sounds just like the author's representation of Radin's conclusion:

Radin believes that a positive result supports “consciousness causes collapse”.
 
#15
Look at the tags provided by the website for this series of articles,

"crackpottery, crankery, dean radin, double slit experiment, James Alcock,parapsychology, physics essays, science, skepticism, Stanley Jeffers"

Seems slightly biased to me lol
I think you may be right. The author basically rejects nearly all parapsychology research:

The “positive” result that he reports suffer from the same problem as virtually all positive results in parapsychology and also many in certain recognized scientific disciplines. It may simply be due to kinks in the social science methodology employed.
Some of the weirdness in the paper, not all of which I mentioned, leaves me with no confidence that there is more than “flexible methods” going on here.
This and based on some of his egregious misrepresentations of Radin's position (In the post right before this one), I am not inclined to trust his assessment here.
 

Paul C. Anagnostopoulos

Nap, interrupted.
Member
#18
The authors appear to believe that in the von Neumann interpretation that consciousness needs to directly observe the particles. This is beyond absurd, because if this were needed, we could never use computers or any device relying on quantum processes, since we were not opening the devices up to "observe" what the particles were doing in order to collapse the wave function. Instead, we sit down in front of the computer and observe the outcome of all the processes.
I don't think they believe that. What they probably do believe is that an arbitrarily long chain of mechanisms and time delays before the state is collapsed is simply not going to work. If you toss in seven mechanisms and a year before anyone looks at the results, it's a bit bizarre to insist that everything was in superposition all that time.

Consider Shimon Malin's scenario:

"Suppose a measurement of an electron's spin component along some direction is being measured. The result can either be "up" or "down". The result of the measurement is automatically communicated to a printer that can either print "up" or "down". If human consciousness is what causes the collapse to the observed state, then the collapse would only occur when someone read the printout, and not before. Now suppose that the printer has just enough ink to print "up", and not enough ink to print "down". Furthermore, if the printer runs out of ink, a bell sounds in a secretary's office. If the secretary hears the bell, a collapse to "down" has clearly occurred before the bell sounded. If the secretary does not hear the bell, a collapse to "up" must have occurred--and no human interaction was necessary at all."

It's an interesting exercise to try to explain how that scenario would work if consciousness is necessary for collapse. In particular, we have to consider whether active consciousness is required, or whether passive consciousness or nonconsciousness will do the trick.

~~ Paul
 
#19
I don't think they believe that. What they probably do believe is that an arbitrarily long chain of mechanisms and time delays before the state is collapsed is simply not going to work. If you toss in seven mechanisms and a year before anyone looks at the results, it's a bit bizarre to insist that everything was in superposition all that time.
But that's the von Neumann interpretation, and that's what this absolutely brilliant mathematician, who laid down the foundations of quantum mechanical formalism, said was a consequence of the mathematics. It doesn't matter if you or the authors feel that this would be bizarre, because the entire history of quantum theory has been bizarre mathematical predictions and every single one of them so far has been experimentally confirmed. Everything from the EPR paradox, to the quantum Zeno effect, to quantum teleportation, delayed choice, delayed choice quantum eraser, etc. The bottom line is they did not falsify this interpretation.


Paul C. Anagnostopoulos said:
Consider Shimon Malin's scenario:

"Suppose a measurement of an electron's spin component along some direction is being measured. The result can either be "up" or "down". The result of the measurement is automatically communicated to a printer that can either print "up" or "down". If human consciousness is what causes the collapse to the observed state, then the collapse would only occur when someone read the printout, and not before. Now suppose that the printer has just enough ink to print "up", and not enough ink to print "down". Furthermore, if the printer runs out of ink, a bell sounds in a secretary's office. If the secretary hears the bell, a collapse to "down" has clearly occurred before the bell sounded. If the secretary does not hear the bell, a collapse to "up" must have occurred--and no human interaction was necessary at all."
It's pretty obvious from this scenario that there is a clear human interaction (with the secretary).

Paul C. Anagnostopoulos said:
It's an interesting exercise to try to explain how that scenario would work if consciousness is necessary for collapse. In particular, we have to consider whether active consciousness is required, or whether passive consciousness or nonconsciousness will do the trick.

~~ Paul
It's pretty obvious that the secretary's conscious perception is what made any of that happen (within the von Neumann interpretation). She is the end of the von Neumann Chain.
 
#20
Massimiliano Sassoli de Bianchi seems convinced that he has solved the Observer Problem...

Can we really take him seriously?
He has a paper on Radin's experiments in question here:
http://arxiv.org/pdf/1207.0804v1.pdf

Actually, thinking in this way, or hinting to such a
possibility, can only bring more misunderstanding to the
already highly controversial issue of the PK-effect, as
well as on the possibility of reaching a more mature un-
derstanding of what von Neumann’s “Process 1” are all
about: a simple physical instrument effect, and not a
psychophysical effect
! What I’m here stressing is that
it is highly improbable, considering what we today know
about quantum mechanics (and that the founding fathers
didn’t know), that the theory would ever need the inter-
vention of the consciousness to explain the measurement
process. Also, in the highly unlikely circumstance that
such an intervention would nevertheless be required, the

way consciousness would be involved in the measurement
process is in an case very different from what is actually
needed to explain an intention-based PK-effect, able to
alter the statistical predictions of quantum theory (von
Neumann’s Processes-1 cannot be used to select a
pre-ferred outcome).
(note: emphasis added)
Sorry for the weird formatting since it was copied from the PDF.

Process 1 of the von Neumann interpretation is regarding the "free will choice of the experimenter" as Niels Bohr said. It is selecting the experimental setup to essentially create a scenario that can ask nature a question, so to speak. Process 2 is the Schrodinger equation, which is deterministic, and it is process 3 which is conscious collapse. I am unsure of where the author got the idea that PK is supposed to be explained by process 1; it is within process 3 where it is thought there may be a biasing of the outcome that uses the leeway found within the uncertainty principle. Radin has suggested, based on experiments with Markov chains, that perhaps this operates in a teleological way, but who knows at this point. Either way, it is a part of process 3, not process 1, of the von Neumann Chains that PK seems to operate within.

Also, as it was recently lucidly pointed out by Yu and
Nikolic [4], if the role of the consciousness would be in-
strumental in producing the collapse of the wave func-
tion, then each time there would be a collapse there
should also be a conscious representation of the corre-
sponding outcome. But this also means that the collapse
of the wave function should actually never occur if the
corresponding result has not been duly registered by a
conscious observer. Now, an analysis of the already exist-
ing empirical results, for instance in typical “which-path
experiments,” already strongly suggest that a conscious
access of the information about the outcome of an ex-
periment is not a necessary condition for the collapse of
the wave function to occur. In other terms, it appears
that in consideration of the already available experimen-
tal evidence, the hypothesis of a link between the human
mind and the collapse of wave function would have been
already falsified in a number of occasions.
Here he is quoting the paper that I commented on earlier here. These authors did not falsify the von Neumann interpretation, and this current author is trying to use this as evidence against the von Neumann interpretation.

But independently of the pertinence of the analysis
in [4], which although certainly needs to be completed
it already casts strong doubts on the pertinence of the
consciousness’ hypothesis, there is in fact a much more
important reason for abandoning it: we simply do not
need it! Not in the sense that, following David Mermin’s
famous provocative injunction, we should only “shut up
and calculate!” and avoid getting involved in whatever
metaphysical speculation, but in the sense that: we don’t
need it to explain von Neumann’s Processes-1, and the
mechanism producing the transition from probabilities to
actualities, during a quantum measurement.
Four points:

1. it is correct to say that effectively we do not need conscious collapse to perform the experiments and the mathematics for the experiments in question, but that does not falsify the von Neumann interpretation.

2. The paper in [4] did not falsify the von Neumann interpretation in any way.

3. Again, it is process 3 in which PK is thought to operate, not the experimental setup in process 1.

4. To say that "we don’t need it to explain the mechanism producing the transition from probabilities to actualities during a quantum measurement" is wrong. At this time, there is no known mechanism for collapse. So how can he say that we do not need consciousness? Maybe it is involved, and maybe it isn't, but when we have no known mechanism for it (assuming it is mechanistic to begin with, which may not be a valid assumption), it is just plain wrong to make a definitive statement that we do not need consciousness to explain collapse.

To rewind a bit, towards the beginning of this paper the author writes:

My disagreement is about the position of Radin et al.
regarding the fact that the results they have obtained
would appear to be consistent with a consciousness-
related interpretation of the quantum measurement prob-
lem, and that their double-slit interference experiments
would have somehow tested, and confirmed, the “con-
sciousness collapse hypothesis.”
It is the purpose of the
present note to try to explain the reasons of my disagree-
ment.
Here again we see misrepresentation of Radin's conclusions from his paper:

Dean Radin said:
What the present experiments do not unambiguously demonstrate is that the observed effects are necessarily relevant to the QMP [Quantum Measurement Problem]. That is, what we observe was a decline in interference correlated with periods of observation versus no-observation. This is consistent with a consciousness-related interpretation of the QMP, but there may be other ways of explaining these effects that do not require quantum concepts.
 
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