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Measurement Problem & Objectivity

  1. Jul 23, 2014 #1
    I have never been to the pyramids in Egypt. I'd love to go one day. I am sure their configuration will be just as others have seen, and as the visitor map describes. Why is it that my experience will correspond exactly with others' experience if I am collapsing quantum potential with respect to my own independent observation/measurement? Is that proof that the pyramids have their own inherent physical existence beyond observation and 'the measurement problem'? Is their a remote chance that my digital camera will capture a photo of the pyramids that does not look at all like what I see while I press the shutter release?
    thx, CJ
  2. jcsd
  3. Jul 23, 2014 #2


    Staff: Mentor

    Because QM is a theory about observations that appear in assumed common-sense macro world existing independent of us.

    Forget stuff you may have read about conciousness causing collapse and other stuff. What they forget to tell you is what I said above is a perfectly valid view of QM:

    At one time two great figures in QM, the Mathematical physicist Wigner and Mathematician Von Neumann, for reasons no need to go into here, thought conciousness was involved. Von Neumann died early, but Wigner when he heard of some early work on decoherence by Zurek realised it was no longer required and abandoned it.

    Last edited: Jul 23, 2014
  4. Jul 23, 2014 #3


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    Thanks for the link to the very nice article by Lubos Motl. I had pretty much stopped visiting his blog, but my reasons weren't about science (I'm not going to bring up what they were about).
  5. Jul 23, 2014 #4


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    You are in good company:

    “It’s not easy to ignore Luboš, but it’s ALWAYS worth the effort.” - attributed to John Baez

    "For the next three years, I, Scott Aaronson, will not respond to anything Luboš says, nor will I allow him to comment on this blog." - from Scott Aaronson's blog.

    For the op: There is no experiment showing any influence of consciousness on experimental results in qm.
  6. Jul 24, 2014 #5
    Thanks Bill, I didn't quite understand your first comment... did you mean that quantum effects are for a quantum world? and not necessarily valid in a conventional macro-existence? thx CJ
  7. Jul 24, 2014 #6


    Staff: Mentor

    I presume you mean when I wrote:

    QM is a theory about observations. Observations are things that occur in the world we see around us. There is nothing deep about this - its simply what we mean in everyday use in saying we observe something. It's not meant a concious observer is required etc etc - something happens and we observe it. It happens regardless of if it is observed - its very common-sensical - but unfortunately exposure to popularisations make people think there is more to it - there isn't.

  8. Jul 24, 2014 #7
    I thought that measurement is what made the Double-Slit experiment so paradoxical / interesting? Excuse my naiveté, but is this not the case anymore?
  9. Jul 24, 2014 #8


    Staff: Mentor

    One of the issues with the double slit experiment is its often used to motivate the full quantum formalism. But they then do not go back and show how that formalism explains it.

    Here is how the laws of QM explains it:

    What aspect you find paradoxical/interesting is up to you. Personally what I find interesting about it comes from the path integral approach which shows its the paths available to it that is the key - but again that's just my view - the real explanation is the laws of QM - the path integral approach is easily derivable from those laws as many textbooks detail.

    But what an observation is, is not one of those weird things, it does not require a concious observer etc some popularisations prattle on about. That aspect is very common-sensical. The issue actually is its too common-senical and pinning it down rigorously is not easy, but that is by the by, if you are interested do a post and we can chat about it.

  10. Jul 24, 2014 #9
    Thanks Bill for all this time you given my question. It has really let my creativity wander. Excuse the next part as I am a little punchy from a long tiring day. I wondered about decoherence in the car on the way home. I’ve loosely aware of it… from what I gather it’s how a quantum system looses its strangeness into the surrounding environment.... or perhaps there was never any strangeness to begin with... maybe quantum weirdness only emerges from trying to bully subatomic particles through an obstacle course - a ‘closed’ atomic system for purposes of scientific study? Maybe the universe is totally and naturally classical and only goes all goofy after a good unnatural prodding. I am not sure. I think it is valid to ask though; is it effectively classical? Purely classical? appearing as classical?

    Maybe decoherence is primary… driving entropy, the arrow of type, creating 3 space dimensions, black holes… maybe it makes DNA twist into that funny swirly shape… maybe it is the common dominator of every scientific phenomenon we may care to entertain.

    Whatever the common-sensical world is, consciousness is surely a part of it (I feel you all cringe after reading that)… a major part of it without a doubt … admittedly the buck-toothed backwoods cousin in comparison to the equations and lofty scientific knowledge... and maybe its consideration won’t make computers faster… or Q-bits behave… but what if it were like decoherence? What if consciousness is decoherence? OR, what if consciousness is the most fundamental thing ‘not-in-the-universe’… similar to how light is not contained in space, but rather space is contained in light? Ie. speed of light…. Now there’s something fundamental.

    Yes, sorry for all this... this isn’t a philosophical forum after all… I only ask that you remember as you go grabbing the universe by its equations and squeezing every drop of calculation out of it, remember that better technology has not made for a better world, its just made better technology—Yes, do pursue science... it is our greatest expression of the human intellect… but I’d like to think that we are more than that too; well, happy abstractions everyone – I need some sleep now.
  11. Jul 24, 2014 #10


    Staff: Mentor

    Statements like that leave me scratching my head.

    Of course its a major part of the commonsensical world we see around us that concious observers exist - that's beyond dispute.

    But the issue is does that commonsensical world exist independent of those concious observers - and the answer is - its part of what commonsensical means.

    You mean the technology that allows you to have forums like this so people can discuss such things has not made for a better world. I am sitting here right now in Brisbane Australia where the hospitals are under huge strain from a flu epidemic - and people are dying. But I also got a flu shot so for me its very low risk. No one can tell me that not having a flu shot available hasn't enriched my life beyond measure - nor that the people lying in misery in hospital, and maybe even will loose the battle with the disease, will not in future get a flu shot every year and thank their lucky stars technology provided it to them.

    Again views like that I simply do not understand. Sure technology can be misapplied, but as Issac Asimov said - the answer to technology misapplied is technology well applied - not the bemoaning of it in the first place.

  12. Jul 25, 2014 #11
    I was touring the forums and came across this. I hope I am not derailing this interesting conversation with my following (long, hopefully not too irrelevant) [STRIKE]comment[/STRIKE] essay:

    Before I became the physics graduate that I now am, I used to enjoy thinking philosophically about QM. Having a "rigorous" training in QM taught me what it is and what it's not, but made me even more bewildered by it. Here is an interesting philosophical question:

    It seems impossible to me to distinguish between aspects of science (e.g. QM) that come from the way the universe behaves, and those that come from the physical laws of how humans, as physical entities, interact with it. We are observing the universe through interactions governed by physical laws of the universe. Why do we have this faith that the laws of physics won't dictate that we will not be able to interact with the universe in such a way that would produce results that conform to our logic which is just another physical process? (I admit this is sort of nihilistic).

    QM is nice because it side-steps this mostly useless question, and simply tells us what we will observe. People in general only have problems when trying to interpret the reason it works.

    A picture that I have always had in my mind, which I would like to share with you, is similar to classical, non-linear, light- matter interaction (warning: I have not studied it in full rigour).

    Imagine radiation incident on some non-linear material. Electromagnetic radiation changes the optical property of matter, which in turn affects the radiation, which then changes the optical properties, which then changes the radiation even further....we go into this chicken-egg loop, but at the end, we can write some perturbation series which converges (under some conditions). Some behaviour emerges out of this back and forth interaction loop. We cannot factor out the effect of the field and that of the matter. The two are entangled beyond hope.

    Similarly, consider this thought experiment: humans (bodies, brains, and clever apparatuses) interact with the universe in a certain way. This interaction changes the state of the universe, but also that of the experimenters, meaning that the way they are interacting with the universe is now affected - which in turn means that the state of the universe must also be different than that in the intermediate step, which means that.....etc. At the end we have some sort of convergence - some behaviour of both universe and experimenter emerges as experimental results.

    Sorry for the rant. And apologies for hijacking the thread, and for posting immature, erroneous, and generally bad ideas.
  13. Jul 25, 2014 #12


    Staff: Mentor

    My view is much simpler.

    Physics is a mathematical model. The mathematical model par excellence is good old Euclidean Geometry we all hopefully learnt at school. What are points - they are supposed to have position and no size - same with lines - neither exist. Yet no one has any problems applying it - we don't get caught up in the issues people carry on about with QM, relativity etc such what what is reality - people who regularly post here know the drill - its really the same thing over and over. But for some reason everyone seems to have none of those issues with Euclidean geometry.

    But if you think about it its really the same issue. What's an observation - its usually utterly obvious what it is. QM is a theory about observations like Geometry is about points and lines. There is nothing more to it really. Want to know what it tells us about reality - figure out what Euclidean geometry tells us about reality and I strongly suspect exactly the same answer applies to any other mathematical model such as QM.

    Me - I simply take it as a fact we have mathematical models that describe the world around us - there is nothing more going on. What is reality - its what our models describe.

  14. Jul 25, 2014 #13
    Well that is upsetting news that people have died in your country Bill. I feel for them and their families. We went through a severe flu episode a few years ago here in Toronto, Canada. I am sorry if it has affected you or your family in any way.

    I am sure your country has military out posts in every town and city administering vaccine 24 hrs a day to combat the spread… I mean, people are dying here, this is serious… our most precious resource is our people (or is it more like mile long line-ups at the clinics between the hours of 9am and 5pm like we had?). Hmm…

    I imagine the military has stopped all air, train, boat, and car travel… maybe even urged people not to visit family members but rather call them on cell phones instead… I hope everyone has one of the sanitizing dispensers that you don’t have to touch… if you are fortunate enough maybe you can work from home on a computer, no even having to go into the office… watch out you don’t touch public railings or door handles if you have to venture into populated areas.,, isn’t modern life great?

    If I wasn’t so over-worked trying to make enough money to pay for the technological conveniences of modern life I might have enough time to get some fresh air, sunlight, and exercise… maybe even be strong and healthy enough to ward off the flu myself. Spend quality time with my children and teach them how to live instead of relying on qualified daycare workers to do for me because both myself and my wife work to make ends meet.

    Yes, perhaps we’d all be a little healthier if we didn’t need all the stuff we buy over and over again, then throw away into the garbage and buy again and again. Yes, thank heavens for technology… for giving us this wonderfully convenient, sheltered, alienated, selfish, wasteful, life.

    I think I’d rather go back to a hunting and gathering life style… love to feel the exhilaration of bringing back an animal to the village for everyone to feast from… see the admiration of all my peers and talk later at the camp fire about the drama of the hunt that day. Lie under the stars at night and innocently wonder about what its all about… a life of balance again. If I get sick and die of the flu while doing it, it would be worth it, worth it to know I lived while I was alive… I think that was a line in a song decades ago. Anyway… to you and yours Bill, be well.

    I wonder what mathematical model there would be to describe creativity? Nevermind, I don't want to know.
  15. Jul 25, 2014 #14


    Staff: Mentor

    Mate, every flu season a few young and fit people die from it - in Australia - Canada - USA - anywhere. Its just during a bad outbreak more die and hospitals become overloaded with those struggling to fight it off. The strains this year though tend to target the young and healthy - which is why its such a concern - and hospitals become overloaded.

    Its normal - some die from it - no need to evoke emergency measures with the military. There is however a media campaign to tell people its very important to get vaccinated and hospitals will be under extreme pressure if it reaches epidemic levels eg:

    People were warned it was likely going to be worse than usual but most generally ignore it. The trouble is it takes a while for the vaccine to work and getting it now wont help much. That's the real problem - we do not know during any flu season if it will reach 'epidemic' levels like it has this year, so people don't take it seriously enough. Even though it was thought it would be bad this year - they still ignored it. Human nature I guess.

    And I am sure you would have equally enjoyed the 20-30 year life expectancy as well.

    Anyway this is way off topic and I wont be saying any more about it - its for a different forum - not this one.

    The process one uses to come up with models should not be confused with the model.

    Last edited: Jul 25, 2014
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