Spooky or not spooky, that is the question.

Discussion in 'Physics & Math' started by quantum_wave, Jan 27, 2016.

  1. Fednis48 Registered Senior Member

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    You're quite right that the orthogonal measurement can be thought of as "left" versus "right" spin. Google the "Bloch sphere" if you're interested in a way to formalize this. Whether an electron spin's up/down orientation is a "different property" from its left/right orientation is a bit of an ambiguous question, because as far as I know "property" is not a precisely-defined term in quantum physics. You might say that they're the same property because they stem from the same physical source, or you might say they're different properties because they are described by orthogonal bases. The important thing is to remember that electron spin does not act like a single, vector degree of freedom, because measurements along different orientations do not commute. As you noted, measuring spin along one axis resets the probabilities along any orthogonal axis to 50/50, so a single measurement of "Where is the spin pointing in 3D?" is not possible. In that respect, up/down and left/right spin behave more like position and momentum in a single direction than like positions in orthogonal directions. (E.G. simultaneous knowledge of both is limited by an uncertainty principle.)
     
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  3. Waiter_2001 Registered Senior Member

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    Correction: Xroot^X

    Apologies for the interuption. Please continue...
     
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  5. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    Hmm, Walter

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    .
    It is a good time to mention the uncertainty principle, because it comes into play in the Superposition101 lecture, not only when talking about the independence between the characteristic of spin on different axes, as in the color vs. hardness measurements, but again later in the lecture when the mirrors are placed in the paths of the elections. It is associated with entanglement at that point because if we measure spin on one axis, say the vertical, the lecture notes say that the spin "right or left" on the orthogonal axis is entangled. I can accept that since it will measure 50/50 on a subsequent measurement, but I'm just babbling.

    What I want to ask is about the final set of experiments where the mirror is inserted in the path of the single electrons. The existence of the mirror changes the results from the earlier experiments, in that after determining the color, for example, then sending only one color through the hardness box, and then reflecting the two out flows from the hardness box with mirrors, into a combined path, the out flow becomes 100% one color. That is spooky, because without the mirrors, the same experiment yields a 50/50 result.

    It seems to mean that the electron that reflects off the mirror, as a mirror image of the electron, is physically somehow different from the unreflected electron. I observe on a macro scale that when I look in the mirror; my right becomes the mirror image's left. Since the magnetic deflection of the electron by the "box" determines right and left, i.e., hard or soft, for example, does the mirror change the physical orientation of the moving electron?
     
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  7. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    The spooky thing from the video is the Superposition state. The Superposition video and lecture notes make the case that when we measure a photon or electron on one axis, the entanglement involves the superposition of the states relative to spin on the orthogonal axis. That might be a very basic case of entanglement, but the quantum nature of particles, as yet unknown as to the mechanics of it, is the "realm" where entanglement exists. It is a big deal in the advancement of quantum level technologies like encryption, quantum computing, miniaturization, and even teleportation experiments.

    So at this point in the thread, I am comfortable that from the perspective of those who don't ignore the Hidden Variables Interpretation which supposes "incompleteness" of QM, the "spooky" thing that has to be explained physically and mechanically, is the Superposition state that characterizes entanglement. I would appreciate the opinions about that simple conclusion from the membership.
     
  8. Fednis48 Registered Senior Member

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    I think you're assigning too much significance to the mirrors; their only function is to change the paths of the two beams. The important part is that the beams are re-combined into a single path before measuring, so by the time a measurement is performed, it no longer gives any information about the spin. Without the mirrors, we can tell what an electron's spin was based on which beam it was in, so any measurement will necessarily tell us about the initial spin.

    I basically agree, with one semantic caveat. It sounds like you're confusing the concepts of superposition and entanglement a bit. Superposition is any situation in QM where a system is in multiple states at once. When you measure color and leave the system in a 50/50 combination of hardness, that's superposition. Entanglement is more specifically when superposition leads to correlations between otherwise independent variables. When Alice and Bob measure orthogonal polarizations, the states of their two photons are entangled with each other. When an electron passes through a magnetic field, its spin becomes entangled with its spatial position. But when you just put something into a 50/50 superposition of states, there is no entanglement because that's just one variable.
     
  9. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    I'm not making much progress, am I? However, does this work? Superposition seems to be the spooky part if it is a state where two of the states that can be measured independently are "merged" into one state called superposition?
     
  10. Fednis48 Registered Senior Member

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    Almost! It's a superposition before they're merged; you can measure the electron to be on either of the two paths, and the total state is a superposition of the two paths. If you merge the two paths without ever measuring them, the system behaves as if the two paths were never split apart in the first place. That's what makes superposition different from classical probability: you can merge (i.e. interfere) superposed states to produce a result that is different from what either state would produce on its own.
     
  11. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    Thank you Fednis48.
    I see it now, Superposition is the spooky part.
    Entanglement, in and of itself is not spooky, except that the particles (or even objects) that can be entangled are composed of quantum states in superposition.
     
  12. Fednis48 Registered Senior Member

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    725
    I haven't heard anyone phrase it that way before, but that's not a bad way to think about it. I have one last thing to add about how entanglement enters the picture. If you just have local superposition, you can explain the splitting-and-merging results with local and realistic hidden variables. Such variables would obey a set of laws quite different from classical mechanics, but you can come up with rules that explain all the observations. When you have not just superposition but entanglement between particles, you can in some sense "stretch out" the superposition to significant spatial distances, which rules out all but the most exotic hidden variable models. So while superposition makes QM spooky, entanglement amplifies the spookiness.
     
  13. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    I agree, and that was the goal, to pin point the spookiness.

    Earlier in this thread I posted a "blurb" about the foundational medium of space, and how the advance of waves through the medium was described as being assisted by a series of local quantum events, local "oscillations" of wave/spot/wave action, at the foundation of the universe, and therefore in the foundational background of space.

    "I will say that in my model everything is connected at the speed of light and gravity, so no FTL in my book. My version is more like your lattice of entanglement-strands, but I don't go for "strings". I won't be a complete bore by giving you a Fringe post on my version, but it has to do with a foundational background in space where there is continual wave action at the local speed of light, and that causes an oscillation at every point in space between tiny expanding spherical waves and their subsequent wave intersections/overlaps. The intersections inflict a brief time delay on the advance of the spherical waves and momentarily convert wave energy to mass in the tiniest increments, in what I call a momentary high energy density spot [HDS] at the point of every convergence. Because the HDS is surrounded by the lower energy density of the expanding "parent" waves, there is nothing to contain the high energy in the overlapspace, and so the HDSs "burst" into new expanding spherical waves, perpetuating the oscillation at all points in the foundational background. That background then serves as a mechanism to advance more meaningful waves like light waves and gravity waves at the local finite speed of light and gravity. It is akin to the Christiaan Huygens version of how a light wave advances at a finite velocity through space."

    From the perspective of the Hidden Variables Interpretation "fans", QM is incomplete. A description of foundational quantum level action of the tiniest wave intersections, the formation of momentary high energy density spots as a result of those wave intersections, and the subsequent new waves emerging out of the spots, is one direction that I have contemplated that might be drastic enough to qualify as an alternative idea, in any brainstorming that is intended to discuss ways that QM might be incomplete.

    Do you, or anyone, want to comment on that, or offer another brainstorming idea to add to the list. One rule of brainstorming is that there are no "dumb" ideas; they all have the potential to spark related or corresponding ideas in the minds of others.
     
  14. CptBork Valued Senior Member

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    The only theories which could be sufficiently "exotic" to beat Bell's theorem are those which fail to satisfy its very simple, basic postulates. Bell's theorem shows that any theory involving locality and determinism (other than those which invoke supernatural predeterminism) will necessarily fail to make the correct predictions for existing experiments, no matter how complex one makes the inner workings of said theory.
     
  15. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    The brainstorming idea featured locality, but I'm not sure it is deterministic, since the state of the oscillations comes close to random.
     
    Last edited: Feb 13, 2016
  16. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    Actually, in a universe that consisted only of the quantum level action of the foundational background, i.e., in a version of such a model that did not have any matter, and no light or gravity waves, the oscillations would appear to be random at every point in space and time. In that case the model features both locality and randomness at every point in space.

    A good example of waves traversing the background with the assist of the oscillating wave/spot/wave quantum action is the recent LIGO detection of gravitational waves, which I mention in this post on the Quantum Asymmetry between Time and Space thread, here.
     
  17. Fednis48 Registered Senior Member

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    I'm not sure what you mean by this, but don't confuse randomness with pseudorandomness. If a variable is uncorrelated with anything and varies uniformly from shot to shot, it's pseudorandom. On the other hand, a variable is only truly random if you can't predict what value it will take, even given perfect information about the state of the universe. The latter, stronger sense of randomness is what one needs to get around Bell's theorem; if your model says a measurement result can be predicted given a perfect description of the local universe near the measurement, then it doesn't work.
     
  18. CptBork Valued Senior Member

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    The thing is, without determinism (i.e. every cause having a unique, well-defined effect), the whole concept of "locality" is almost meaningless on its own. Locality by definition means that events of the recent past can only affect something if they're located sufficiently close to whatever they're affecting, i.e. information can only travel at a finite, limited speed. You could postulate a probabilistic theory in which meaningful correlations between events only occur over timelike separations (less than speed-of-light information exchanged), but that would fail to account for the results in Bell tests. I'm actually thinking those experiments ought to be considered as ruling out locality altogether (at least in a manner consistent with the speed of light as the limit), with or without underlying deterministic mechanics.
     
  19. iceaura Valued Senior Member

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    The notion of "determinism" has never really made sense at the level of fundamental "cause" - in the upper levels one ends up arguing in confusion that humans never make decisions because their brains are physical objects, in the lower levels one is baffled by the ineradicability of randomness, in between one is always resting on approximation and likelihood as if they were given form.

    Cause and effect determinism is a (very useful) mental shorthand, something that suffices in a given situation. Elevating it to a fundamental principle of the universe is taking it beyond its useful range.

    http://quod.lib.umich.edu/p/phimp/3...science?page=root;size=150;view=image#pagenav
     
  20. Confused2 Registered Senior Member

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    A bit belated but... How does the Many Worlds interpretation avoid the recursion problem where the result in the observer universe is the sum of all (infinity?) universes when the observer universe also makes a contribution to the result that it observes? Is the observer universe (ours) 'special'?
    (Hi Brucep!)
     
  21. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

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    The gist of this thread has boiled down to attempting to brainstorm with members about what the nature of particles and particle interactions would have to be like in order for the spookiness to make sense, the spookiness being superposition, and the entanglement quantified by the correlation experiments where the results violate Bell's inequalities. The topic has not motivated much in the way of ideas, :darn:.

    If there is no possible explanation that could make sense to the human mind, then do we just resort to the idea that there is an element of the Supernatural at work? I don't think we do; no one on a science based forum will take that stand, will they? Maybe I'm wrong about that, and maybe the lack of ideas, brainstorming, is that members are okay with there being no understandable explanation for the spookiness.

    I'll try to add something to my idea about a foundational wave energy background at the level of the tiniest possible wave interactions that I characterize as a continuous and self-perpetuation wave/high density spot/wave process; an oscillating background that assists in the advance of larger wave fronts that exist "on top" of that background. It goes something like this:

    That oscillating background would represent a foundational level of energy in the universe that would exist even if there was no matter, and therefore no electromagnetic or gravitational wave energy that is associated with the presence and interactions of matter. It is the amount of energy in space at the state of complete equalization, meaning there is no useful energy over an above that basic foundational level that produces the monotonous oscillations between wave convergences and tiny spherical waves emerging from each tiny high energy density wave convergence.

    Does anyone understand that concept, or should I elaborate, draw some circles and show high energy spots at the points where the tiny spherical waves intersect, before introducing some brainstorming ideas about how particles might be constructed and move through such an oscillating background ("field")?
     
  22. iceaura Valued Senior Member

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    One door: the notion that mathematics used in this way amounts to construction of a virtual sensory organ; extrapolating from its use in other physical systems, where it is involved in creating "perceptions" such as momentum, density, centers of gravity, potential energy, fields of force, electromagnetic waves, and the like. We use math to perceive what we cannot otherwise, lacking the sensory apparatus (or confused by optical illusion, the automatic logarithmic compression of sensory data, etc). It's a last resort - what we can see and feel and hear we "understand" more easily - but it works.

    Like a colordeaf person studying the equations of the wavelengths of light, or the energy blind person studying the equations of potential and torsion for a suspension bridge, we "probability numb" study the equations of the quantum world.
     
    Last edited: Feb 22, 2016
  23. Confused2 Registered Senior Member

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    I like that. In another Universe rpenner linked to a lecture by Scott Aaronson - negative probability - which explained more/better.
     

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