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Locality vs Nonlocality

  1. May 16, 2004 #1
    My own simplistic definitions:

    Locality-What happens here does not affect anything anywhere else in the universe whether there exist a reference frame or not.

    Nonlocality-What happens here is related to everything everywhere else in the universe. Quantum entanglement shows perfect nonlocality. The use of a reference frame is not needed. If there is a reference frame then superluminal speed can distort the physical meaning of reality.

    Are these acceptable?Do they make any sense?
     
    Last edited: May 17, 2004
  2. jcsd
  3. May 18, 2004 #2
    Why everything everywhere else? Where not something somewhere else?
    Can you give some more detailed explanation? If I recall correctly, nonlocality can also be described within a reference frame.
     
  4. May 18, 2004 #3
    It seems to me that a relative velocity is always associated when comparing two reference frames. When comparing three frames, there are three relative velocities. When comparing four frames, there are six relative velocities. In special relativity, these relative velocities are all equal to the speed of light in vacuum.

    But in nonlocality, what would be the relative velocity between an object located at the origin of the reference frame and an object located at infinity with respect to this frame? The spacetime geometry must be distorted in order to bring infinity closer to the origin and not violating the superluminal speed.
     
  5. May 22, 2004 #4
    Nonlocal forces result when two particles linked such that heir combined angular momentum, for example is zero. Assume the particles are separating at the speed of light and aftere a few years the anglular momentum verctor of one of the particles is determined to point 'up'. Under these conditions the momentum vector of the 'twin' particle is instantly set as 'down' in order that the total angular momentum be conserved at zero. (See the Clauser experimetns). Relativity constraints are not violated as no signal linking the particles through some space time mechansim is observed. it is as if the particles are sharing a "angular momentum" vector in a nonlocal state.
     
  6. May 22, 2004 #5
    Are you talking about time-delayed quantum entanglement?
     
  7. May 22, 2004 #6

    HallsofIvy

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    This makes no sense at all. In the first place, special relativity does NOT assert that the "relative velocity" between any two reference frames is the speed of light! In the second place, there is no "object located at infinity" with respect to any frame.
     
  8. May 22, 2004 #7
    Two frames of photons are always separated by light speed in vacuum. The object at infinity is a photon where the potential field (e.g. gravity) is exactly zero.
     
  9. May 26, 2004 #8
    You are asking a question with an implication that some observable reality is intrinsic to the nonlocal. Whoever you referred to that described nonlocality 'within a reference frame' is making the same mistake. Nonlocality isn't the topic of a theory. It isn't a temperature, an accumulation of stuff, matter, things we observe. As the "nonlocality" is described in the quantum literature, See J.S.Bell, Theoretician, whose collection of papers tell the best tale. "Speakable and Unspeakable in Quantum Mechanics".

    I'll give you a birds eye view that might be assimilated.
    In the 1920s some small birds in England, blue-tits, were found to have started poking holes in aluminized milk borttle covers and sucking the cream from the bottle. Within a decade or so this observation had spread to cover the whole of England. The same phenomena was observed in the low countries, Luxemborg, Holand , later.

    The bkue-tit with an average life of 21/2 - 3 years was never observed to exceeed a few miles from it location of birth, never to cross channel waters. In the years 1939 - 1940 the milk delivery system in the low countries had been totally interrupted by WWII. - a five year span of no blue-tit sightings re milk. In 1945 the milk bottle openings began a rapid rise in frequency.
    How does one explain the mechanism whereby the blue tits spread the technique of poking holes in aluminum lids and sucking milk from the bottles?

    After you go through all the 'observable' possibilities you are left with some inkling of nonlocality. The birds were utilizing some transfer of information that did not include chirping signals that said "hey, watch this guys. First you give a sharp poke, then dip in the beak and suck . . ." . Of course if English blue tits get information this way, what about other organic systems, like . . ., well you fill in the blanks.

    You might try looking at it like this. Everything in front of you, at this very instant that you are aware of, the crt, the desk, your hands, tip of the nose, the walls, fading memories of yesterday, lights, shadows, everything there in front of you observed, is, well simply observed, or "speakable". You, on the other hand, are unobserved, nonlocal, do you get it?

    The essence of the observable, or speakable is the nonlocal. Sorry to be the one to bring this to your attention, but that's the way it is. You did bring the matter up did you not? The quantum theorists, excepting the starter of this thread, haven't grasped the reality yet, (hell, they're not looking) being mired in the self-imposed blindness of current qt, but eventually they will be observed acting out the impersonation of the old adage, "... the blind carpenter who picked up his hammer and saw".
     
  10. May 26, 2004 #9
    Not in those terms. I am talking about the Clauser experiments. I do not see time delay here unless you mean the time from the moment the particles began moving to the instant one of them was measured. But the time between measurement of A and affect seen in B isn't measurable. It is more like instantaneous as if the particles shared a nonlocal element eseential to the observed state that was later interrupted by the measurement process.

    I mean it like this. Electrons in strabnsition in SternGerlach arrangements are observed to be in either a +1/2 or a -1/2 "spin state". As far as I can glean from th eliterature each electron is thougth to be in one or the other state before entering the SG segment. Think aot a system where the electron is oscillating -+-+-+-+- until the process is terminated by a plarization event, such as entering a SG magnetic field/gradient system Now we have an observed state generated upon first effective contact with the field and the unobserved state that is no longer seen, ergo it is a nonobserved state. Understanding that the +-+- switching process is not turning things "on and off" like a wall light switch, that states are expresseed and supressed, or observed and unobserved at any instant of time. Sometimes it is more economical to mother nature to have the unobserved processes share with multiple observed states.

    This is what I mean.
     
  11. May 26, 2004 #10

    DrChinese

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    "The essence of the observable..." Where do you get this stuff? Does it come in visions while you sleep?

    For the rest of us, science is involved in useful descriptions of the universe. Clearly, the QM local/non-local debates have been going on for most of a century, most famously considered in the 1935 EPR paper. So I am not sure how theorists are failing to "grasp" some essential reality via "self-imposed blindness". Comprehension of what non-locality implies would be high on the list of many physicists.

    As before, if you have a specific assertion you would like to place into consideration - something that others can agree as a starting point - please, share. In the meantime, please note that "essence" means difference things to different people. Perhaps the essence of the observable is in fact the observer. who knows? Or maybe it is the way the observation is conducted?

    At any rate, the "essence" of the EPR/Bell/Aspect line of reasoning is that reality cannot be local. (Or is that something which you deny too, geistkiesel?)
     
  12. May 28, 2004 #11
    The "essence" of the observed is nonlocal. Those hidden elements that guarantee the "observed" state is their nonlocality and but for their dynamic activity no observed state is possible.

    Example: In the transition of state, S -> T -> S, say in a Stern-Gerlach arrangement, The S state is polarized to the T state during transit through the SG T segment. Upon exit the transition T-> S event occurs upon leaving the field/gradient region of the T segment into field free space. Unlike the compass needle that always returns to north after a perturbation by operation of the earth's magnetic field, the T -> S trasiition has no such observable force, hence the forces are unobservable, or nonlocal.

    How does the particle remember the proper orientation of its magnetic spin vector (AKA its seminal inertial frame)? The nonlocal elements making up S are the guarantors of the reformation of the S state process, call them 00, hence S = S(1 00) where the 1 is arbitrarily assingned the spin value of '+'. In the polarization event (P)S(1 00) - > T -> T(1 00 00[T]), where the 1 here is arbitrarily the '+' of the T state. Upon depolarization the event is

    (Pinv)T(1 00 00[T])-> T( _ 00 _ _) -> S(1 00) = S or +S.

    The 00 are the nonlocal elements of the observed state S, or in cryptic words, the 00 are the essence of the observed state.

    This one I did when I was wide awake.
     
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