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Mind over matter reality or myth?

  1. Feb 3, 2016 #1
    Hi, I’m new to the forum and I would like to ask some questions. I’m not a physicist –for some reason that I’ll always regret I chose Business Studies- and my knowledge of physics is limited to high school, physics books and documentaries; which I must have watched them all by now.

    Anyway, for many years I’ve been intrigued by the same issues that Einstein had with quantum physics -for example, nonlocality, quantum entanglement, the observer effect (commonly confused with the uncertainty principle), and so on and so forth- so I would appreciate if anyone could help me solve my doubts.

    The first issue, which is the simplest, is the observer effect on the double slit experiment. Every single physicist that I saw explaining the double slit experiment -Brian Green, Michio Kaku, Neil deGrasse Tyson, and so on- reaches a point where he says that the observer is influencing the particles. For example: this is a literal quote from the first video about it that I found on YouTube “Dr Quantum –Double Slit Experiment”:

    “The particle behaved differently, because it was aware that it was been watched.”


    First of all, I think all these documentaries and physicists are confusing a lot of people with these claims and are creating a lot of controversy; as this is not the case: neither we can see the particles travelling through the double slit, nor the particle cares whether anyone is watching or not, and therefore our consciousness has no influence on the experiment. I just checked in the Wikipedia for curiosity, and at least they got it right: the observer refers to an instrument, not a person.

    In any case, the experiment shows that if we do not try to find out through which slit the particle passed, it behaves as a wave, passing through both slits, and create an interference pattern; but if we try to determine it, then it behaves as a particle, and passes just through one slit. Now, my question is: doesn’t this mean that the equipment that is detecting the path of the particles is interfering with them, and therefore preventing it from passing through both slits and creating the interference pattern? If this is the case, what is all the fuzz then? Is it all because of those who claim the observer is a person, and therefore give the impression that physicist are claiming that mind over matter is a fact?

    I’ll post the rest latter. Thanks for your help.
     
    Last edited: Feb 3, 2016
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  3. Feb 3, 2016 #2

    jfizzix

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    One way I like to look at the double slit experiment is to take a step back and describe the particles and measurement device together quantum mechanically. What you find is that the interaction of the device with the particles destroys the coherence between the different paths, and you see no interference pattern.

    If you make this interaction weak, so that the measurement device only has a little information about which slit the particle went through, you find the interference pattern is not quite as clear as it would be if there were no interaction. As the interaction strength grows, the visibility of the interference pattern gets worse, until with maximum information, you have zero visibility.
     
  4. Feb 3, 2016 #3
    Hi adfreeman, I'm new to this forum and have been asking a similar question for the last couple of years. To get to the heart of the matter, it the KNOWLEDGE of which path, or slit. A more modern version of the experiment:



    Sean Carroll talking about the different interpretations:



    Hope this helps, I know it did for me.
     
  5. Feb 3, 2016 #4
    Thanks for the reply.

    Could it be that in your example "weak" means that not all particles interfere with the measuring device; therefore some don't interact at all, and pass through both slits, and the rest interact with the device, and therefore just pass through one or the other slit?
     
  6. Feb 3, 2016 #5
    Thanks for the reply and the videos.

    You might also be interested in reading this other thread I found: Observation and its role on objects/matter/particles
     
  7. Feb 3, 2016 #6

    Nugatory

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    "Every single physicist"? The three you have listed (I'm not counting Dr Quantum because I don't think he is a real physicist or even entitled to call himself "Dr" - no record of anyone by that name ever having received a doctoral degree from any reputable school) are pretty much the only contemporary physicists saying that. And they aren't saying it in any of their serious work, just in their pop-sci stuff which is intended to entertain rather than to inform.

    Yep... We spend a fair amount of time here trying to unconfuse people who have been confused by this stuff.

    No, there's more to it than that. If you send your quantum particles towards the two slits one at a time, each particle will produce a single dot on the photographic film just as you'd expect a proper and well-behaved classical particle would. However, over time these dots will build up an interference pattern - even though the dots are produced one at a time, many seconds apart. That behavior is inconsistent with our classical notions of both waves and particles, and tells us that quantum objects are fundamentally and interestingly different from anything in the macroscopic world. That's a big deal even without the drivel about mind over matter.
     
  8. Feb 4, 2016 #7

    A. Neumaier

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    In modern quantum experiments such as the colliders at CERN or experiments done using photodetection, all observers are mindless machines. People only look at the final statistics produced by fully automatic computer programs that process the information from fully automatic recordings of the observations. Nothing ever involves mind or consciousness, except interpreting the final statistics.
     
    Last edited: Feb 4, 2016
  9. Feb 4, 2016 #8
    Yes, of course, it's not "every single physicist" in the world. What I said was "every single physicists I saw explaining the experiment".

    Yes, I understand all that and I also find the experiment fascinating. But what I meant to ask is: isn't it clear that it's the particles interfering with the slit detector that prevents them from forming the interference pattern?

    Yes, that's what I thought; however, in all these documentaries they literally say that it is the observer that's influencing the result, which gives the impression to many people that by observer they mean a conscious mind.
     
  10. Feb 4, 2016 #9

    A. Neumaier

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    That impression is created on purpose by those writing for the general public because it is the stuff that makes quantum stories sell to the public at large. It has its precedents in the early days of quantum mechanics when it was not yet clear how quantum mechanics could be understood most rationally, so that even famous physicists played gedanken experiments involving consciousness to find out the limits of the theory. Since it is this speculative part that is most easily communicated to lay people, and since people at large expect quantum physics to be a kind of magic, popular accounts are heavily colored by it. But whoever wants to get serious about understanding quantum mechanics must first get rid of all this magical talk about it.
     
  11. Feb 4, 2016 #10

    PeroK

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    I found this quotation recently:

    "On the surface, an intelligible lie; underneath, the unintelligible truth."

    Perhaps the popular science presenters have no choice but to present an intelligible lie.
     
  12. Feb 4, 2016 #11

    Nugatory

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    That line of thinking is a huge improvement over the stuff in those videos (which should be treated as entertainment, not education).

    There's more to it than just the interaction with the detector though. Some interactions will kill the interference pattern when others won't; for example if we place polarizing filters behind the slits (with no other detectors) we'll get an interference pattern when the fileters are aligned parallel but not when they're aligned at right angles. And in some delayed choice experiments (the wikipedia section on Kim's delayed choice quantum eraser is decent) we get an interference pattern or not according to whether the particle had two paths available to it or not - even though the particles undergo the exact same interaction with the slits in both cases.
     
  13. Feb 4, 2016 #12

    Nugatory

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    There are enough examples of good popularizations, even in quantum mechanics, that I don't see the need to accept bad ones. Simplification is unavoidable, and without the mathematical formalism there's no way of being precise.... But we can simplify without misleading the way that Dr Quantum does.
     
  14. Feb 4, 2016 #13
    I realise they have to make physics entertaining, especially since science is not very popular in the world we live in. But what they are doing is exaggerating the analogies so much, that they stop being true; they are practically lying on purpose to the public. And I'm not referring to the Dr. Quantum and such, which I just chose because it was short and to the point, I'm referring to top scientists like the ones previously mentioned, or for example, Alex Filippenko in the science documentary "The Universe" from PBS, who literally says in the episode "Microscopic Universe" while explaining the double slit experiment:

    "... when my eyes are closed, it behaves like a wave. But then, at the last second, before it hits the screen I open my eyes and decide to observe it." And the narrator continues: "At that moment, the electrons in essence, become particles."

    No wonder there are a lot of quacks out there claiming that now quantum physics confirms all sorts of paranormal claims. I don't think going to such extremes does any good to anyone, as it creates a lot of confusion.
     
    Last edited: Feb 4, 2016
  15. Feb 4, 2016 #14
    Yes, I was planning on getting into the polarizing filters latter on when I ask about the Aspect experiment in Paris for the Bell tests; which I'm still researching a bit more.
     
  16. Feb 4, 2016 #15

    PeroK

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    You're perhaps being a little unfair on poor Dr Quantum. The last science programme I tried to watch on QM on British TV was presented by Jim Al-Khalili (and he's a real physicist, I believe). After 15 minutes he'd said nothing beyond a vague description of the photo-electric effect and I left him sipping a cocktail in a 1920's jazz bar. And that was BBC4!
     
  17. Feb 4, 2016 #16
    I feel I might have to chip in my two cents :wink: I watched Dr. Quantum, and I find it, along with almost all popularisations of quantum physics on TV (+Youtube), incredibly superficial and even misleading. I have to say I am very annoyed by such misinformation of the unsuspecting public! And even I am a layman!
     
  18. Feb 4, 2016 #17

    Nugatory

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    You mean it's even worse than I thought?! :eek::eek::eek:
     
  19. Feb 5, 2016 #18

    bhobba

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    Even in the standard beginner textbooks on QM many myths are perpetuated:
    http://arxiv.org/abs/quant-ph/0609163

    I am not 100% sure the full monty can be given at the beginner level. Because of that I cut a fair amount of slack in these treatments. My issue however is in the books at the intermediate level. They don't go back and correct these misconceptions, somehow expecting students to pick up when things have changed. As far as the double slit goes here is a good intermediate treatment:
    http://arxiv.org/ftp/quant-ph/papers/0703/0703126.pdf

    But just to show a proper understanding of QM is not that easily won, even the above is incorrect when viewed from a more advanced viewpoint:
    http://arxiv.org/abs/1009.2408

    Unfortunately QM seems to be one of those areas you need to constantly unlearn things as you progress. It seems to be the nature of the beast.

    Personally I think a whole new approach is required such as the following:
    http://www.scottaaronson.com/democritus/lec9.html

    But we have quite a few people that actually teaches this stuff posting here (I am not one) and they are not sure such an approach is the answer either. So who knows.

    Thanks
    Bill
     
    Last edited: Feb 5, 2016
  20. Feb 5, 2016 #19

    jfizzix

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    It's possible, that one could have an interaction where particles in one set of quantum states interact, and particles in another set do not, say, if the interaction works only is the spin of the particles is in a particular state, and if the weakness is controlled by a slight polarization rotation into that ideal state.
    The tradeoff between which-path information and fringe visibility is more general than that, though (it is in fact an exotic variety of quantum uncertainty relation), so this particular example would only be a special case.
     
  21. Feb 5, 2016 #20
    I just finished watching this documentary for the Nth time; it's about Bohr and Einstein's argument regarding entangled particles transmitting information faster than the speed of light, which seemed to prove Bohr right when Alain Aspect carried out in an experiment John Bell's inequality tests.



    (The experiment is explained in minute 24:55 of the video)

    In the experiment, they produce 2 entangled photons with lasers from a calcium atom; which they found out have the same polarization, as they only passed through both polarized filters when they were in the same orientation -which I guess is also why in the double slit experiment that Nugatory mentioned in post #11 the polarization filters must be in the same orientation for the interference pattern to form. Then they needed to find out if the entangled particles had the same polarization from the beginning, as Einstein though -as well as me-, or if they acquired that property later on, as Bohr believed. So they built something like this to test it:

    aspect0.jpg

    The entangled particles travel from the cylindrical chamber in the center, along the tubes, passing through one of 2 polarized filters with opposite orientations, which is decided by their respective switch. The switches change faster than the time needed for any information to travel between photos at the speed of light. Now, on the documentary they say that even in these conditions the photons have the same polarization, but, even though I watched it a dozen times, I don't think they clear how that was proved. I mean, if the particles still have the same polarization after the switches, how does that prove that they did not have it from the very beginning. It's not like the switches are changing any property on the particles, just changing their direction, and therefore the polarized filter they will pass through. Isn't it?

    Can anyone please explain it? Thanks
     
    Last edited: Feb 5, 2016
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