QM randomness...

Discussion in 'Physics & Math' started by Seattle, Jun 2, 2017.

  1. iceaura Valued Senior Member

    You have to consider that as a central component of one of the best established fundamental theories in all of science, supported without contradiction by the accumulated evidence of a century of research.
    And since there is no evidence of their existence, and well established theory denying their existence, we regretfully set that unsupported theory aside in favor of something with more support than a psychological need for a will-o-the-wisp causality that we find nowhere else.
    Although there is another out: superdeterminism would allow Bohmian explanation without conflict - and without causality, of course.
    Such incompatibilities are normally settled by a preponderance of evidence.
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  3. iceaura Valued Senior Member

    This is the second basic misreading of the first two pages of that link you have posted. I doubt you understand his point.
    It has nothing to do with precision in one's notion of causality, but instead with explanatory power and necessity. It's not that nobody can formulate notions of causality, it's that they have become almost worthless in rigorous theory, and they never have been necessary.

    For example: You have posted a notion of causality that you assert produces Bell Inequality violations. That illustrates Norton's point perfectly - how is something a "cause" that both does and does not exist, producing effects that both did and did not occur?

    Not sure what your trouble is. Classical mechanics deals with, among other things, the elastic and inelastic collisions of bodies possessing momentum - that's what produces Brownian motion. So far so good?
    Last edited: Jul 19, 2017
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  5. Write4U Valued Senior Member

    Last edited: Jul 19, 2017
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  7. Schmelzer Valued Senior Member

    The violation of Bell's inequality is this contradiction with evidence. One is sufficient to falsify a theory. Don't forget the centuries of research supporting Newtonian theory and the thousands of years supporting geocentrism.
    LOL. dBB theory is as well supported by empirical evidences as any other interpretation of QT. The difference are the various conceptual problems other interpretations have with measurements, collapse, Schroedinger's cat and so on.
    Superdeterminism is nonsense. It would allow to explain everything and make all experiments meaningless. The universal conspiracy theory with the Creator who has defined the initial conditions as the conspirator.
    In this case, there is no chance. But there is an easy way to settle the conflict, and even a known one. GR as an effective field theory, without metaphysical pretense of being a fundamental theory of some "spacetime".
    Here is what Norton writes:
    I say Reichenbach's common cause is the counterexample, it is as substantial as possible for a physical principle, given that it can be used to prove theorems like the Bell inequalities. If one thinks that "substantial" means even more, namely that the principle alone should make testable predictions, one has not understood Quine's objection that it is never a single theory taken alone which is tested. I have read attempts to show that it does not work and found them wanting. https://plato.stanford.edu/entries/physics-Rpcc/ If you like, we can discuss them. A refutation of some theories is what makes a principle substantial.
    This makes no sense. Reichenbach's common cause principle shows that the violation of the Bell inequalities prove the existence of causal influences faster than light. This is simply a refutation, by observation, of theories which claim such causal relations do not exist. In dBB theory such causal relations are described nicely, in a form where they act immediately.
    Classical mechanics is the classical example of a deterministic theory. Brownian motion the classical example of a Wiener process, that means, of a statistical theory, which does not make deterministic predictions. So, "Brownian Motion is no less deterministic than classical mechanics - and no more." is simply nonsense.

    That theories which describe approximations of a fundamental deterministic theory may be statistical theories, and, similarly, approximations of statistical theories deterministic theories, is the point I have made, presenting some examples. So there is no disagreement about this. This does not mean that the theories are no less/more deterministic, which is what I name nonsense. Brownian motion is a statistical theory which does not describe any deterministic laws which rule the movement of the Brownian particle. Similarly, say thermodynamics has deterministic equations guiding its fields, like the temperature field T(x). It does not derive thermodynamics from a more fundamental theory. Such a derivation connects different theories, some of them fundamentally random, some of them fundamentally deterministic.
  8. iceaura Valued Senior Member

    No, it isn't.
    It requires superluminal transfer of cause and effect. That conflicts with all available evidence, and is supported by none.
    That's not true.
    Bell's Inequality is an elementary logical deduction from very simple principles, proved long ago. No "physical principle" is involved.
    No theory proves physical existence.
    Theoretical conclusions are not observations. That's kind of basic, in science - theory answers to experiment, and not the other way around.
    And it accounts for Brownian motion in the same way - and just as completely - as it accounts for a handful of ball bearings rolling around in salad bowl - if anybody were silly enough to want to handle Brownian motion that way.
    Nothing except convenience requires one to use statistical theory in handling Brownian motion. And statistical theory does sometimes make predictions - such as various thermodynamic events - that most people describe as deterministic. Air leaking out of a hole in a pressurized tire, for example.
    It is nothing of the kind. It is a physical phenomenon. It is observed.

    Multiple theories apply. The causal ones are the least convenient, and least informative, and least accurate - they are approximations, mostly.
  9. Schmelzer Valued Senior Member

    Simple "no"s without supporting arguments disposed.
    No. "Superluminal transfer of cause and effect" is not some claim about observable effects, thus, cannot be in conflict with observable evidence.
    No. The deduction made by Bell is based on assumptions like Einstein causality which are physical.
    This is not what I have claimed, thus, irrelevant. A variant of Bell's theorem proves that from Reichenbach's common cause follows that if the BI are violated for space-like separated events then there exist superluminal causal influences.
    Whatever the diffuse "answers to" is supposed to mean, according to standard scientific methodology, the other way around: Theories make predictions about results of experiments. These predictions can fail - bad luck for the theory. Theory is prior, the prediction follows, then the experiments which confirms or falsifies the prediction (even if the historical order may be another one, so that we can find that a theory is already falsified by an experiment made earlier, the sequence is similar: First, there is the theory, which is followed by the derivation of the prediction, which is followed by the recognition that the prediction is in conflict with the earlier result.)
    Nothing except convenience requires one to use theory X or Y to describe the phenomenon A. This does not change the fact that X is a deterministic and Y a stochastic theory, so that the claim "X is as deterministic as Y" is nonsense. (Beyond the fact that convenience imposes usually very strong hints in favor of one or another preference.) Word games mingling the observable effect named "Brownian motion" and the theoretical model used to describe it are not helpful.
    Statistical theory makes predictions (else it would be quite useless as a physical theory). But these are predictions about statistical averages. How "most people" name this is completely irrelevant. If the deviation from the average is small enough to be irrelevant, the relations between the averages can be used for an approximation, which is, itself, a deterministic theory, because its fundamental equations are deterministic.
    Wrong. If a theory is causal or not has no influence on accuracy, is independent on them being approximations, contain information about causal connections, thus, are more informative. If the information about causal connections is uninteresting, then a non-causal simplification (say, the minimal interpretation) may be more convenient, but so what?
  10. The God Valued Senior Member

    Simple questions....open for all.

    1. Is it still open for conclusion that Uncertainty principle is our inability to measure both the parameters (say x and p) accurately simultaneously?

    2. Is it still open for conclusion that actually observation/measurement is an invasive process and hence what we are measuring is bound to change due to this invasion, it is just that at quantum level effect of this invasion is very significant?

    3. Neutron Star concept is primarily based on increased momentum due to reduction in dx, a direct implication of Uncertainty Principle, why should momentum increase as per Uncertainty Principle as there is no measurement there? Why cannot this situation be handled under classical mechanics?

    4. To detect or measure parameters of electron, we need a photon, electron-photon interaction is well texted and substantial, the invasion by photon is clear and well documented, are we eliminating this effect of photon on electron? Or it is not required.
  11. iceaura Valued Senior Member

    It's mysticism. You require it for psychological comfort, although you recognize it can never be part of scientific theory because it is not part of observable reality. That was my original point - causality is a basic tool or aspect of human thought, not of the observed and observable universe.
    No, it's not irrelevant. It's how "causes" get to be causes. Air pressure becomes a "cause" in this way, for example. Heat is a cause. Gravitational force is a cause. Causes are very handy mental tools.
    And you make Norton's point for him - you can keep your causality as a fundamental property of the universe only by emptying it of physical reference, of temporal sequence, of every property that a "cause" is intuitively supposed to possess - including, in this case, abetting analytical advantage and progress.
    It was an observation of fact, not theory - the causality dependent approaches are approximations chosen for convenience, and to take advantage of human mental capabilities. When you need rigor and the highest accuracy, you use the formal theory.

    There is no such thing as "information about causal connections" until after one invents the shorthand, convenient, folk science causal description. For example, one can obtain a lot of information about phlogiston - a theoretical cause of heat transfer - from one's research: and it's good, valuable information in its appropriate arena. With it one can design insulators, measure heat flow very precisely, figure out a lot of things. Likewise with Newton's gravitational force - very useful cause.

    That's how causality works. There's nothing wrong with it, if it's kept in its place. That can be surprisingly difficult, though, as we see.
    Confused2 likes this.
  12. Dinosaur Rational Skeptic Valued Senior Member

    From the God Post 107
    It worse than our intuitive notions about this problem & there is experimental evidence strongly supporting the Principle.

    The Principle claims that it is not a problem with measurement technology, a POV believed & advocated by many, including some with serious knowledge of physics. See The Meaning of Quantum Theory by Jim Baggot, an excellent book for lay persons. He admits to various naive notions held by him while a graduate student & later when a PHD researcher into Quantum Theory.

    The properties of a Bose-Einstein condensate provide strong supporting experimental evidence.​

    Note that temperature is a measure of velocity at the molecular or atomic level.

    A Bose-Einstein condensate is a group of atoms (or perhaps molecules) chilled to almost absolute zero & thus known to be almost motionless.

    Each individual particle seems to occupy to occupy a much larger than normal volume of space & the volumes can overlap to the extent that it is difficult (I think impossible) to identify individual particles.

    BTW: Einstein & others view momentum (mv) as more fundamental than mass. They might it consider more fundamental than velocity. The principle is actually stated in terms of momentum & position.

    In a lecture to experts Einstein stated that his thoughts leading to General Relativity started with the assumption that momentum was a conserved quantity. An expert asked if he considered assuming that mass was conserved, which would have led to different conclusions & if not, why not.

    Einstein replied: “Isn’t it obvious that momentum is more fundamental than mass?”

    It is interesting that it was known since the time of Newton that gravitational mass & inertial mass were equivalent.

    Einstein was the first to realize that this equivalence was significant at a very fundamental level. His pondering over the equivalence led to General Relativity.
  13. river

    Perhaps more knowledge upon , Zero Point Field would help .

    From what I have read so far , is that , every quantum physicist is aware of this Zero Point Field . But ignores it .

    Correction ; It is Zero Point Energy , which is being ignored by physicists .
    Last edited: Jul 20, 2017
  14. The God Valued Senior Member

    But does it completely rule out the option in question?

    Simple argument, temperature may not be the measure of velocity at quantum (sub atomic and sub nucleonic) level!
  15. river

    At absoulte zero matter does not exist .

    Yet is closest that sub-atomic matter motion can ever get to stillness .
    Last edited: Jul 20, 2017
  16. Schmelzer Valued Senior Member

    Mysticism is something opposite to realism. It is the very rejection of the normal common sense, in favor of some deep Truth, revealed only to deep thinkers able to overcome this despised common sense, and revealed by deep mathematical Insights, in particular symmetries. Mystics have to reject common sense notions like realism and causality.
    No, there is no need to name something deterministic to accept it as a cause.
    Sorry, unable to make sense of this. Of course, the temporal sequence of cause and effect is not questioned if you accept faster than light causal influences. By the way, I do not use causality as a fundamental property of the universe, but as fundamental for the scientific method.
    So what? Reichenbach's common cause principle is formal enough to be used in formal theory.

    That the naive folk theory of causality defended and proposed by Norton is useful too, no doubt. It does not invalidate the approaches which are formalized.
  17. iceaura Valued Senior Member

    Such as tossing GR in order to assume superluminal cause/effect, because you need it to shoehorn causality into your interpretation of QED and its supporting evidence. The deep truth of causality is not to be questioned.
    Yet another example of the "plasticity" Norton mentions. We now have causes that do not determine effects.
    Even more striking, in the case of QED we have causes that determine both B and not-B simultaneously - convenient, but not exactly common sense.
    Yes, it is. Unless you toss GR. The different temporal sequences of event possible in different frames of reference, according to GR, are now in communication - no longer separated by the limiting speed of information transfer.
    Which is thereby divorced from physical reality - that universe we would like to explain and analyze somehow is now fundamentally unapproachable via the scientific method.
    And GR, QED, and Darwinian evolution, are no longer sound scientific theories - not to mention thermodynamics, which loses its 2nd Law.
    And it leads to predictions of Bell Inequality violations, thereby removing physical reference from the causality it supports. Norton discussed this continual feature of attempts to impose a presumption of causality on increasingly sophisticated theories - maybe reread?
    Norton did not defend or propose any theory of causality. That is your third posted basic misreading of the first two pages of that link.
  18. Schmelzer Valued Senior Member

    This is not about claimed Truths of particular theories. This is about the scientific method which is not to be questioned. Finding realistic, causal explanations for observed correlations is what distinguishes science from magic and astrology.
    Of course, the scientific method has some plasticity.
    No. Don't worry, for you this is not no simultaneously.
    Which is what I do. I have an ether interpretation for the Einstein equations of GR, as the GR limit of my ether theory of gravity, which has some absolute time.
    No, there are causal theories for everything, for gravity as well as quantum theory. Thermodynamics is well understood and not a problem at all for causality, except you want to create a problem by vague use of it. And what are your problems with Darwinian evolution I don't know.
    No need. Once there is a normal causal realistic and physical interpretation of quantum theory, there is no basis for claims about "removing physical reference".
    No, it is based on 5. A Folk Notion of Cause. "I will try to outline one possible folk theory that I think fairly represents one mainstream view of what it is to be causal."
  19. iceaura Valued Senior Member

    And which does not need causality.
    The concept of a cause has become essentially meaningless, in the attempts to jam it into theories that do not support it.
    It is. That's in the assumptions of the proof of Bell's Inequality - there are only a couple of ways to deny that simple set of assumptions, and you have already rejected a paradigm shift in logic itself.
    No theory is a "problem" for causality - setting up a "cause" and using it in some way that aligns with the theory is standard human analysis, normal and effective thinking. You don't have to, of course, any more than with other modern theories.
    Demonstrating the contortions necessary to fit causality in where it is not a useful shortcut, and the "plasticity" necessary in the concept of a "cause".
    Folk science is widespread, yes. It is very useful. When hardcore rigor is needed, the established modern theories are employed, instead.
    There isn't.
    And you misread that as Norton basing his thesis on that one view (which is in fact mainstream).
  20. Schmelzer Valued Senior Member

    Let's compare this with
    You see, the notion of causality I propose is not only a meaningless "useful shortcut". It leads to serious consequences. Of course, only if one "rejects a paradigm shift in logic itself". And the couple of ways consists of A: rejecting realism as well as causality, in their formal, hardcore variants (EPR criterion, Reichenbach's CC), which allow to prove theorems. B: Accepting a preferred frame.
    We have hardcore rigor in the proofs of Bell's inequalities. Does iceaura become the replacement of paddoboy, who accepted only "established modern theories"? Whatever, the various proofs of the Bell inequalities are established.
    I already know that I misread everything, and the description of how I misread it is, as usual, also wrong, so, once you give no explanation how to read it, zero information.
  21. iceaura Valued Senior Member

    There is nothing "meaningless" about the many good uses of causality in human thought and scientific investigation.
    No, it really doesn't. It leads to confusion - a common effect of invoking causation where it is not useful (the single most common source of confusion about Darwinian evolution is the ascription of cause and effect to it - environmental factors "causing" adaptive changes, etc.)
    Of course. I posted that myself.
    I did tell you how to read it. And my description of how you misread it consisted of a quote from your post:
    . Norton did no such thing. He illustrated his thesis with an example.
    And you have illustrated Norton's thesis with several more examples, here in this thread, a couple of which I quoted and pointed to directly.
    Last edited: Jul 20, 2017
  22. Dinosaur Rational Skeptic Valued Senior Member

    From The God Post 111
    That is probably nonsense & not relevant.

    The Bose-Eienstein state is an atomic or molecular level phenomenon & clearly provides support for the Uncertainty Principle.

    BTW: The belief in determinism seems to be like a faith based belief in religion. Radioactive decay & other well known processes show all the properties of random processes.

    To repeat a remark from a previous Post of mine.
  23. The God Valued Senior Member

    I was talking about single electron or nucleon. Try assigning temperature? Bose - Einstein condensate is not a single particle while uncertainty principle is applicable on an electron or a nucleon.

    We have read that radioactive decay is random, probably it is not. It is just that we are not able to decipher the trigger event. As I said there is nothing like True Randomness. If there cannot be true determinism then there cannot be true Randomness.

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