• Michael
    15.4k
    Local realism is just the union of locality and realism. Dr Hanson's experiment appears to demonstrate non-locality, which he himself describes as spooky action at distance.
  • Pierre-Normand
    2.4k
    Local realism is just the union of locality and realism.Michael

    Agreed, though "realism" had a special technical meaning referring to the determinateness of quantum measurements before they are effected. As for "action at a distance" check my short references, especially the last one.
  • Janus
    16.2k


    You are saying that although she might think she could have done otherwise, that she in fact could not have done otherwise, correct?

    If this is correct, and I have read you right, then I am saying that your assertion that she could not have done otherwise is a purely baseless supposition on your part.
  • Andrew M
    1.6k
    Local realism is just the union of locality and realism. Dr Hanson's experiment appears to demonstrate non-locality, which he himself describes as spooky action at distance.Michael

    Hanson's experiment rules out local hidden variable theories but not local realism. In particular, it doesn't rule out Many-Worlds since Many-Worlds doesn't involve any action or communication between entangled particles.
  • Michael
    15.4k
    True, but tom claimed that "Quantum field theory is explicitly local. Copenhagen is local. Many Worlds is local. As a matter of fact it has been proved that QM is a local theory. No sane physicist gives up [locality]!"

    He's right that MW is local, but he's wrong about the rest, so I think my point stands.
  • tom
    1.5k
    Hanson's experiment rules out local hidden variable theories but not local realism.Andrew M

    Feels a bit like going round in circles, but no experiment ever performed closes the "freedom loophole", so single-world realist theories that are absolutely deterministic are not ruled out by this or any other Bell-type experiment.

    In particular, it doesn't rule out Many-Worlds since Many-Worlds doesn't involve any action or communication between entangled particles.Andrew M

    Yes! Many worlds is a local realist theory that cannot be ruled out by any Bell-type experiment, because of the fifth axiom which I omitted:

    5. The uniqueness of outcomes.

    Which is not true under Many-Worlds.
  • Michael
    15.4k
    ...no experiment ever performed closes the "freedom loophole"...tom

    What about Anton Zeilinger's 2010 experiment?

    Third Bell loophole closed for photons:

    There are three main loopholes. The first is the "locality loophole", whereby information about the measurements can somehow be exchanged between Alice and Bob's detectors. The second is the "freedom-of-choice" loophole, whereby the source of the entangled particles can somehow communicate classically with the detectors and affect how the measurements are made.

    Both loopholes were closed simultaneously for photons in an experiment done in 2010 by a team led by Zeilinger after the researchers transmitted the photons distances of up to 144 km between two of the Canary Islands.
  • tom
    1.5k
    He's right that MW is local, but he's wrong about the rest, so I think my point stands.Michael

    OK, let's take the Copenhagen Interpretation and Quantum Field Theory in turn. We can then move onto String theory if you like.

    The CI is a local anti-realist theory. Due to it's purely epistemic nature, it survives any experiment that refutes both local realism and non-local realism.

    For example this famous experiment refutes non-local realism:
    http://www.nature.com/nature/journal/v446/n7138/full/nature05677.html

    You could ask yourself what it means for an epistemic theory to be non-local? The wavefunction, including the combined wavefunction of entangled particles, is not an element of reality. What does it add to say that something that does not exist here, also does not exist over there? CI is able to maintain the desirable features of locality and respecting special relativity by abandoning realism.
  • Michael
    15.4k
    And I refer you again to Hanson's experiments from last year which demonstrate, according to his testimony, non-locality.

    Also, there's this: Non-locality in Quantum Field Theory due to General Relativity

    The simple fact is that, contrary to your claim, experiments have supported nonlocality and sane physicists do reject locality.
  • tom
    1.5k
    What about Anton Zeilinger's 2010 experiment?Michael

    Those are experimental loopholes to ensure that Axiom 3. is maintained. You can't claim that locality is being tested if there are conceivable ways in which different parts of the experiment might influence each other.

    But again, if you give it a moment's thought, do you really think Zeilinger thinks he was unable to set up his apparatus as he wished? Did he close *that* loophole?

    In fact Zeilinger is on record as stating his belief in free will.
  • tom
    1.5k
    And I refer you again to Hanson's experiments from last year which demonstrate, according to his testimony, non-locality.

    Also, there's this: Non-locality in Quantum Field Theory due to General Relativity

    The simple fact is that, contrary to your claim, experiments have supported nonlocality and sane physicists do reject locality.
    Michael

    Non-locality at the Planck scale? Are you for real?
  • Michael
    15.4k
    And yet his experiment closed the freedom-of-choice loophole. So I'm not sure what you're trying to say here. Was he lying? Was the experiment fake?
  • Michael
    15.4k


    According to this, yes.

    But, again, I'm not sure what you're trying to say here. There are experiments that demonstrate non-locality and sane physicists reject locality. What you said earlier was wrong.
  • TheWillowOfDarkness
    2.1k


    It's worth pointing out that distance inevitably means time. Not a mediated travel (e.g. the sun travels 8 or so minutes through space to get to Earth), but a point of the world. In this respect, non-locality has a similar relationship as our own limited observations of the world.

    In the universe of my room, I do not observe other people or computer link to other parts of the world. Within an instant, a message appears out of nowhere, from a place which cannot be assigned to anything in my locality. Something without presence in my space has acted upon my screen. Spooky. The world is bigger than my locality.

    Non-locality is an really an affirmation of both realism and localities. The world I observe is not all of it. Other things are so, not local to me, there beyond what I experience or observe, and they sometimes affect me. And I will never be able to predict them.


    Most working scientists hold fast to the concept of ‘realism’—a viewpoint according to which an external reality exists independent of observation. — An experimental test of non-local realism

    The mistake is in bolded. Independent of what observation? Mine? Anyone?

    Non-locality only precludes observation from my locality. I cannot measure what is not local to me. This doesn't necessarily hold for other localities. We might say the following: something non-local to me could well be local to someone else. No existing state is independent of a locality and the world which might be observed. Yet, non-locality is expressed everywhere, for the world is always more than any one locality.
  • Andrew M
    1.6k
    He's right that MW is local, but he's wrong about the rest, so I think my point stands.Michael

    Fair enough, but this may just be a semantic difference over the meaning of "locality".

    The SEP page on Action at a Distance in QM says, "Yet, the question of whether the EPR/B correlations imply non-locality and the exact nature of this non-locality is a matter of ongoing controversy."

    However "locality" is defined, Hanson's experiment doesn't imply "action at a distance".

    ... so single-world realist theories that are absolutely deterministic are not ruled out by this or any other Bell-type experiment.tom

    I agree.
  • m-theory
    1.1k
    I think you are missing the point. Given the conditions now, the past can be calculated by physical laws. This is how we know the big bang happened. Both General Relativity and the Standard Model have time reversal operators.tom

    Actually initial conditions of the past cannot be determined with any current models.
    You cannot reverse time to determine the initial conditions precipitating the big bang.
    And in fact there are many things that current models simply cannot account for like dark matter, dark energy, the matter/antimatter asymmetry, etc.

    Your point that the current laws of physics are deterministic is a failed point.
    They do not give us a complete account of the past and they do not give us a full account of all the phenomena of nature.

    You want to argue that GR and the standard model are deterministic, they are not.
    Each fails and breaks down taking into account a description of the complete past.

    So no, none of the current laws are deterministic and consistent.
  • tom
    1.5k
    Actually initial conditions of the past cannot be determined with any current models.m-theory

    So, why did scientists look for the CMB?
  • m-theory
    1.1k

    Are you suggesting that the CMB is a prediction about the initial conditions of the universe or that the prediction of CMB is a complete account of natural phenomena?

    It is not.

    Any truly deterministic model would be able to give us the answer as to what are the initial conditions precipitating the big bang.

    If GR and the standard model cannot produce consistent and non-contradictory accounts of the initial conditions of all of causality then it can not accurately be called deterministic.
    .
  • taylordonbarrett
    8
    just going to throw out a couple propositions for you all without getting too deep into this discussion....


    1) the certainty of what will happen in the future is in no way contradictory to our freedom in the present. in theology, we would make a distinction between "foreknowledge" and strict predestination. foreknowledge of the future does not violate free-will in the present. rather, foreknowledge only has meaning if it is truly predictive of free choice. otherwise, it is not true "foreknowledge" (in the theological sense), but is rather simply mathematical deduction.

    2) the naturalistic, atheistic, reductionist worldview absolutely rules out any semblance of free will. for a person to have the ability to make choices that contradict material precursors requires a transcendent, supernatural ability. the mere natural cannot rise above material cause and effect. for this reason, our experience of free-will should give us all very deep pause when considering the origin of this freedom.. not that we possess something great in ourselves, but He who created us in His own image - He is great.
  • Robert Lockhart
    170
    There is a view regarding the perennial Free Will debate that the main constraint imposed on advancing our ideas concerning this subject arises from the erroneous assumption that the possibility of human moral autonomy – a determination regarding this putative capacity being the sole object of philosophic enquiry concerning the free will question, after all – that the possibility of such autonomy, must in principle be contingent on the possibility of human amoral autonomy, as for example whether I am capable of deciding on the basis of an irreducible personal volition of my own what sweet meat to prefer for dessert.

    According to this argument, considering the questions of moral and amoral autonomy collectively - as opposed to considering them singularly - effectively constitutes a conflation of unrelated questions. The proposition of the argument is that, in that each of these theoretical capacities would proceed from unrelated principles, so the possibility of neither concept is necessarily contingent on the other and therefore that the validity or invalidity of either amoral or moral autonomy is logically co-reconcilable. The possibility of amoral autonomy is regarded by the argument as being contingent on the nature of the nexus existing between the brain and the psychology and that of moral autonomy as contingent on the entirely unrelated possibility of a capacity to acquire objective moral knowledge (assuming for the purpose of the argument the validity of the idea of an objective morality in the first place). The argument postulates that the conception of such knowledge, in being objective and in that respect like say the conception of scientific knowledge, would accordingly not in principle be subject to psychological qualification and therefore that it would be independent of the brain-psychology nexus referred to as being relevant to the consideration of amoral autonomy.

    The central tenet of this argument then is that a philosophic enquiry regarding free will should properly be framed by the question of moral knowledge, a matter unrelated to the causal arguments that are in turn proposed as being exclusively appropriate to what is considered to be the purely scientific question of amoral autonomy.

    Incidentally, specifically with regard to the concept of moral autonomy, this argument potentially provides a straight forward solution to the age-old paradox regarding the apparent incompatabity of a concept of irreducible autonomy with the logical idea that every event must perforce be preceded by a determining cause – the required causal element in the case of moral autonomy being supplied by the role of individual personal experience which, it is proposed, acts to confer such autonomy on an individual in an a posteriori manner.
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