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Roger Penrose and physics

  1. Mar 3, 2005 #1
    Roger Penrose suggests in his new book that the schrodinger cat paradox is an indication of the largest fundamental flaw in science as it now exists. He arrives at the conclusion that the particle/wave duality is not acceptable as a valid reality. Is anyone familiar with any of this? Does anyone have a response?
     
    Last edited by a moderator: Mar 3, 2005
  2. jcsd
  3. Mar 3, 2005 #2
    Welcome to Quantum Mechanics.
     
  4. Mar 3, 2005 #3
    I agree with Penrose

    As the post above me suggest, not only do most physicists accept the wave particle duality, but they embrace it. They will gleefully tell you that it is sometimes a particle and sometimes a wave, and that is just the way it is and you are going to have to get used to it.

    With respect to shrodingers cat, the situation is much worse. Because it is traditional in QM to avoid talking about unobservables, the problem is left unsolved. Logical Positivism (the idea that reality is nothing more than what can be observed, and that there is no point in physics talking about things that can't be observed) is one way of doing physics, and it has dominated the 20th century.

    I think QM is fine, but untill we know what is really going on down there, only then will we be able to explain our observations.
     
  5. Mar 3, 2005 #4
    You do not agree with Penrose. Penrose says that the duality must be elimanated in order for science to make sense.
     
  6. Mar 3, 2005 #5

    dextercioby

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    I hope u missunderstood Penrose.I hope that,if you understood him,he was just kidding...:yuck:

    Daniel.

    P.S.Duality,though not explicitely mentioned in the 6 axioms,is a key ingredient of QM...
     
  7. Mar 3, 2005 #6

    Integral

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    I have always thought duality was more a problem with our perceptions then QM. We seem to have a need to classify things according to what we are accustomed to. Light displays a property we associated with waves, therefore we call it wave like, light displays a property we associate with particles therefore we call it particle like. Perhaps to truly understand light and photons in general we must get past the analogies of the Newtonian world which simply do not apply to QM. Photons are not waves sometimes and particles other, they are always photons. Unfortunately there is nothing in our macroscopic world perception which corresponds to their behavior. We must let the formalisms of QM lead our understanding, not the analogies of our day to day world.
     
  8. Mar 3, 2005 #7

    Andrew Mason

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    Very well put. Waves and particles are just models that we use to describe light. But neither are completely accurate. Both models would predict behaviour of light that we do not see. It is like trying to classify a dinosaur in terms of species that exist today. Was a velociraptor a bird or a reptile? There may be similarities, but the answer may be that it was neither: it was a velociraptor.

    AM
     
  9. Mar 4, 2005 #8
    I did not intend to imply that everything in my post was me agreeing with Penrose, I meant only that I agreed with "the conclusion that the particle/wave duality is not acceptable as a valid reality. "

    Integral has given the standard party line on the issue: because our intuition is unadapted to quantum level phenomena, the only way to make progress is through mathematical formalism.

    I call this "taking the easy way out". Instead of explaining the quantum nature of light we shove it so far under the rug that the question is mocked.

    Dextercioby seems to suggest that the insolvability of this problem is right up there with the axioms of quantum mechanics! "Not only can we not find an answer, but we will assume that none exists, so none of you should bother".
     
  10. Mar 4, 2005 #9

    Andrew Mason

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    The concept of a "solid" does not exist at the level of photons, electrons, neutrinos, and other quantum phenomena. The concept of continuous matter or energy does not exist at that level either. We are trying to adapt a macroscopic model to fit phenomena that are of a fundamental different nature. It is not that light is both a wave and a particle. It has some characteristics of both but is neither. We just don't have a completely accurate model for it. It behaves like a wave on a macroscopic scale and more like a particle at the atomic scale.

    It is a little like asking: is water a wave or a particle? In large volumes, water behaves like a continuous substance and can form waves. But at the atomic level it has discrete molecules which alone have none of the qualities of macroscopic water.

    AM
     
  11. Mar 4, 2005 #10
    Are you suggesting your "perceptions" are not bound by the rules of physics? Sounds sort of meta-physical to me.
     
  12. Mar 4, 2005 #11
    Nope Andrew, you have already bought the party line:

    What you meant to say is [It is impossible in principle to observe a continuous range of energies at the quantum level]. As far as what is really [ontologically] going on, that question has been stifled by the following view:

    "Physics is only concerned with predicting observables" [logical positivism]

    Suppose there exist a man who can guess the answer to any arithmetic computation by a sheer random fluke (he doesn't know how he does it, he is in fact mathematically illiterate, but his answers are always correct).

    The question is: Would you rather be this guy, or would you rather know the
    rules of arithmetic?

    The fact that we cannot observe the true nature of the photon or electron does not automatically imply (ala Bohr) that we can't understand its true nature, is my point.
     
  13. Mar 5, 2005 #12

    JesseM

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    Well, the various "interpretations" of QM which seek to postulate some objective reality behind quantum phenomenon (Bohmiam mechanics, MWI, the transactional interpretation) would all agree with "wave-particle duality" in the experimental sense (like the fact that if you measure which slit a particle travels through, the interference pattern disappears), but they would disagree with it in terms of their picture of what the world is really like (for example, MWI says there is nothing but the wavefunction, Bohmian mechanics says particles have well-defined locations at every moment).
     
    Last edited: Mar 5, 2005
  14. Mar 5, 2005 #13

    Andrew Mason

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    Physics is not concerned. Physicists are. Physicists want to understand the universe. If one cannot predict observable phenomena, then one does not understand it.
    There is no set limit to our ability to observe the behaviour of photons. Why can we not observe their 'true nature'?

    My point is that it doesn't have to be either a wave or a particle. It can be something that has qualities of both but is neither. That doesn't mean we can't understand its true nature.

    AM
     
  15. Mar 5, 2005 #14

    Chronos

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    Why must the universe submit to our version of 'logic'? If you think you understand QT, you are sorely mistaken.
     
  16. Mar 5, 2005 #15

    SpaceTiger

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    It is traditional in science to avoid talking about unobservables because it makes whatever you're discussing untestable. Scientists are properly acknowledging their limits. Whatever their philosophical prejudices, they would be right not to present them as science.
     
  17. Mar 5, 2005 #16
    I have written this many times but i will say it again : there is no particle wave duality in QM !!!

    This duality only arises because of us, being "classical" observers. I mean, we always want to see either a wave or either a particle...Now, the very basis of QM has some very strange properties, like the double slit experiment. They are strange to us, but NOT to QM. We need this duality because we look at QM with our classical glasses and therefore, in order to see, we need to know whether we work with waves or particles. That is all.

    The biggest thing that Penrose dislikes about QM (i am referring to the EOS-article, because he is getting an honorary-phd here at the university of Leuven in Belgium, which is where i do my phd :))is the EPR-paradox : you know that fact that with entanglement it is possible to know two non-commuting observables...chreck out my journal for more info on this.

    Penrose also favours LQG over strings as attempt to quantify gravity...

    marlon
     
  18. Mar 5, 2005 #17

    Integral

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    You have it backwards, the laws of physics are not bound by my (or your) preceptions.
     
  19. Mar 5, 2005 #18
    Andrew Mason

    Your views are quite Agreeable. I am enlightened.

    Please tell me about What is a wave made up of. Since there are waves of different sizes of light, to be so they must be made of something tinnier in order to be of different size.

    I am sorry If I offended someone here, I not a science graduate. But just curious, I hope thats not a crime. Please dont delete this post.

    P.S. Why not devise a new observation strategy to end this debate and be on the correct path ?
     
  20. Mar 5, 2005 #19
    I've heard and read stuff like that before, and have looked back and tried to find a good foundation for it being said or thought that way. I can't find a good one.

    I can only think it comes from people mixing up the fundamental basis, or philosophy, of the competing ideas, or going with one of their own that is really a mixture of the 2 best known (in relating to physics): realism and postivism.

    These people take tenants of postivism, which the Universe appears to follow, but then add snipets of their own here-and-there where it suits them. Then you run into logical absurdities like Schrodenger's Cat, physical interpretations of superposition and collapse of the wave function, the need for a conscientious observer, and even non-locality to try answer things that can't be known.

    The logical absurdity that your perceptions change how the Universe unfolds or that your perceptions are metaphysical is not needed if you take a strict interpretation of postivism philosophy .. that you can't know anything about anything until it is observed. Rather than having mystics surrounding physics, physics is limited to what can be known.
     
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