4

I am learning about EPR and local realism in physics. However, in that context, nobody talks about the philosophical implications and deeper meaning of local realism, objective reality, hidden variable, entanglement and the logic required to understand these phenomena.

I was wondering if you could provide some references for a few papers/books that cover these concepts from a philosophical point of view. I would like to know more about them. It would be appreciated to list a few references ranging from beginner to more advanced materials.

Josh
  • 149
  • 4
  • 1
    Tim Maudlin is self described as sticking close to the ancient Greek idea of physics (“nature”), and if that speaks to you I’d recommend him. He also self describes as making a living explaining EPR and John Bell. I’d recommend What Bell Did and that will help find other good papers. – J Kusin Jul 02 '22 at 16:38
  • 2
    The Internet Encyclopedia of Philosophy has a good article on EPR and its relation to later ideas like Bell's theorem (note that the EPR paper doesn't show that QM is incompatible with local realism, it just argues that QM is incomplete and we need more variables to satisfy something the article terms the 'reality criterion'). For Bell's work I recommend the collection of his papers Speakable and Unspeakable in Quantum Mechanics, especially the paper "La Nouvelle Cuisine" which discusses locality in terms of light cones. – Hypnosifl Jul 02 '22 at 22:40
  • 2
    Also see Bell's paper on the EPR paradox here. One other point is that advocates of the Everett interpretation sometimes argue that it actually restores locality by exploiting a a loophole in Bell's proof where he assumed that each pair of measurements yield a single definite pair of results as soon as both measurements are complete. – Hypnosifl Jul 02 '22 at 22:43
  • As a sidenote, incompatibility of QM with local realism means either a) one should accept global interference or b) abandon realism of the wave function – Nikos M. Jul 03 '22 at 21:53
  • @NikosM. Not if you think there is a preferred spacetime foliaton right? Like someone like Tim Maudlin I believe who accepts quantum nonlocality, is realist because he believes in pilot-wave, and I believe thinks there is a preferred foliation. I’m guessing related to his (paraphrased) believe that even “reversing” everything a la something like CPT is still in, what he calls, time. – J Kusin Jul 05 '22 at 16:10
  • @JKusin I haven't thought of this. What do you mean by preferred foliation of spacetime though? This is interesting. – Nikos M. Jul 05 '22 at 17:40
  • 1
    @NikosM. Something like 10.1 of this: https://plato.stanford.edu/entries/qm-action-distance/ or like this post https://www.physicsforums.com/threads/meaning-of-spacetime-foliations.561128/ (I’m sure there’s more out there just what I could find easily). – J Kusin Jul 05 '22 at 18:22
  • @JKusin I am of the opinion that general covariance principle of GR is somewhat suspect and problematic. What is your opinion on this? – Nikos M. Jul 05 '22 at 18:29
  • 1
    @JKusin - Maudlin believes there is an objective truth about which direction on a time-like worldline constitutes "past-to-future" but he says "a foliation is not required for there to be a lapse of time" (although he does think a preferred foliation may be needed for a coherent interpretation of quantum mechanics; as you mentioned he favors some kind of pilot-wave). See his discussion on p. 116-117 of https://philocosmology.rutgers.edu/images/uploads/TimDavidClass/05-maudlin-chap04.pdf – Hypnosifl Jul 05 '22 at 18:45
  • @Hypnosifl wait I’m not using foliations as a starting point. If Maudlin believes there is an objective orientation, and we experience it, doesn’t that require a preferred now/foliation/hypersurface or whatever (not sure the best term)? Use that to establish the background for “global interference” of Pilot wave. – J Kusin Jul 05 '22 at 19:12
  • @NikosM. I don’t have a good opinion other than what makes inertial frames more real than non-? We may only care about inertial frames and thus covariance always holds. But why do we only care about those, are they more real than the view-from-nowhere or time at the speed of light? How do we scientifically define those terms fully along with our restricted to inertial frame nature? – J Kusin Jul 05 '22 at 19:16
  • @JKusin - I don't see anything conceptually impossible about the idea that time flows along each worldline but that there's no objective "now" uniting worldlines at different locations. As an analogy, if a theist endorses the A theory of time but believes time is an internal property of the universe (no 'time' before creation), couldn't they believe it'd be within God's power to create a bunch of separate universes that all have their own internal time progression but without any pan-universal "now" to answer the question of which events in different universes happened at the "same time"? – Hypnosifl Jul 05 '22 at 19:32
  • @Hypnosifl that’s not excluded by objective direction of time in the first place though? Maybe I have a naive view of objective so don’t let me sway your opinions. I take objective flow and direction of time as the most fundamental, baked into the basic mathematics, for Maudlin. I’d hesitate to say each different universe would call their now objective. You’re right though this sways into theology, metaphysics, and woefully theory of mind probably. So maybe I’ve used an idiosyncratic definition of objective. – J Kusin Jul 05 '22 at 19:57

3 Answers3

1

  1. Tim Maudlin's book Philosophy of Physics: Quantum Theory.

  2. Look at Gerard T'Hooft's (Nobel Prize Winner, 1999) posts and responses on Physics Stackexchange on the subject of determinism, as he is probably the most notable (living, RIP Weinberg) physicist who understands the philisophical implications of the quantum measurement problem. He has his own profile on there, which is just his name. Steven Weinberg also had some interesting philisophical papers about the measurement problem too.

  3. Primary Sources of the EPR paper, and the responses to it, Bell's original papers, and look into the phenomena of decoherence, in conjuction with Wocjeich Zurek's ideas of einselection and quantum darwinism.

  4. SEP page on the subject.

TCoff
  • 365
  • 1
  • 7
0

A good pointer to the EPR-problem is the Wikipedia entry. The article contains links to download

  • the original paper of Einstein, Podolsky and Rosen
  • the reply of Bohr in the same journal
  • a corresponding entry in Stanford Encyclopedia of Philosophy

You find even more references in the article, in particular to Bell's papers. I recommend also "Andrew Whitaker: Einstein, Bohr and the Quantum Dilemma. Cambridge (1996)", Ch. 6 and 7.

Added after reading the EPR-paper: The EPR-paper starts with two useful statements which link physics and natural philosophy:

  • Physical reality: „If, without in any way disturbing a system, we can predict with certainty […] the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity.“

  • Complete theory: „[…] the following requirement für a complete theory seems to be a necessary one: every element of the physical reality must have a counterpart in the physical theory.“

The problematic term from natural philosophy is the term „physical reality“.

The authors do not define the term, their second statement does not fix the kind of relation between the physical quantity from the theory and the corresponding element of physical reality.

Their first statement requires the existence of a map from a certain subset of physical quantities of the theory to the set of elements of physical reality.

While their second statement goes the other way round. It requires for a complete theory the existence of a map from the set of all elements of physical reality to a certain subset of physical quantities of the theory.

Jo Wehler
  • 30,912
  • 3
  • 29
  • 94
  • I do not quite get how this is not a definition of physical reality. Yes, of course there needs to be a mapping from the physical quantities to the elements of physical reality. This mapping is naturally evolving in the pragmatic context of experimentation, measurement, and theory as a standardized system of human practice "against" nature (or physical reality) - the Deweyan "Experience". Or am I wrong here? If so, a complete theory would mean nothing less than that we can accurately describe and predict every element of reality we have pragmatic experience with, even allowing for extension. – Philip Klöcking Jul 05 '22 at 15:52
  • @ Philip Klöcking For an explanation see „Franco Selleri: Die Debatte um die Quantentheorie, Vieweg 1983.“ Referring to the EPR-paper Selleri states on p. 83 „Außerdem könnte das, was uns unmittelbar als räumliche Ausdehnung erscheint, aus Eigenschaften folgen, die sich von unserer Wahrnehmung unterscheiden und zu einer Empfindung führen, welche die wahren physikalischen Eigenschaften topologisch entstellt.“ 1/2 – Jo Wehler Jul 05 '22 at 17:15
  • @Philip Klöcking In my words: E.g., we know that the experience of impenetrability of a solid body is created by the electric forces between its atoms. The latter seems a better approximation to an element of physical reality then the mechanical property of impenetrability. 2/2 – Jo Wehler Jul 05 '22 at 17:15
  • Yes, but why does physical reality have to be eternal and fundamental? Why cannot it be just about however reality discloses itself to us, may it be in immediate sensual experience or mediated through instruments? Why does it have to be "wrong" that a thick titanium plate is impenetrable for most kinetic effects below significant relativistic speeds, just because our description of the fact changes? Of course, the definition is about modern physics but the core of what "reality" and "completeness" means in these citations seems to me inherently contextualised by possible (ie. past) experience. – Philip Klöcking Jul 05 '22 at 18:16
  • @Philip Klöcking The description of impenetrability from your example does not seem „wrong“ to me. But it is the description of an observation, not the explanation of an observation. We approach elements of physical reality by explaining our observations on the basis of physical theories. - Possibly I did not get your point. Therefore: What about elaborating your comment to a separate question? – Jo Wehler Jul 06 '22 at 03:58
0

David Bohm (1917–1992) followed the implications of EPR to its cosmic conculsion. e.g. books. Ervin László comes to mind too - review. All interesting but very speculative. The EPR that can be named is not the enduring and unchanging name.

Bohm's Gnosis: The Implicate Order

Bohm believes that the bizarre behavior of the subatomic particles might be caused by unobserved subquantum forces and particles. ... [He] believes that this "hiddeness" may be reflective of a deeper dimension of reality. He maintains that space and time might actually be derived from an even deeper level of objective reality.

Chris Degnen
  • 5,777
  • 2
  • 15
  • 23