A member of the Vedanta Society wrote:
As you know, quantum mechanics is the most successful theory in the history of mankind. The agreement with experiments is more than 1 part per billion. The cell phone in your pocket is a glowing tribute to it! And yet, debates about interpretation are going on for some 90 years without any resolution. In fact some Nobel laureates like Weinberg and ‘t Hooft do not believe in any interpretation! The reason for majority believing in Copenhagen interpretation is that it is mostly epistemological...
Bohm’s interpretation (theory) has to agree with experiments and well established theory like theory of relativity...
... It would be nice to continue this discussion. I would like to know about feelings of various members of this group about Bohm’s model.
My reply: =================================================
These are all complex, important issues, which have generated a huge amount of secondary confusion as the waves of thought get reflected many, many times, like an image reflected in a series of fun house mirrors.
That kind of reflection and distortion happens in many areas. For example, I just returned from giving a plenary talk at the International Joint Conference on Neural Networks (IJCNN17), where some people casually attacked that "bad old Von Neumann model of computing." But Von Neumann, like Bohm and Einstein, learned and grew and changed many times in his life. At the IJCNN history session, I discussed the important conversations of Von Neumann, Wiener and McCulloch which actually created the neural network field, a new paradigm which continues to grow and is in a major growth spurt right now. Bohm and Einstein also went through stages of thought, which have confused other people.
To begin with, does Bohm's model contradict special relativity? I have an old (unreliable?) impression that Bohm came from upstate Pennsylvania to Princeton, to work with Einstein, and that his most important driving goal in physics was to strengthen Einstein's view of reality, which I lately call "Einsteinian materialism." Einstein himself worked hard to develop a kind of new unified field theory in his later years, using new differential geometry, but I myself have mostly worked with the earlier version of his vision, epitomized in the "already unified field theory" which won John Wheeler (of Princeton) the Nobel Prize.
Einsteinian materialism appears at first to contradict the long emerging feeling in physics that "the universe looks more like a great mind than a great machine." But just as Wheeler discovered that ideas which appear to be in conflict may already be unified, if we look more closely, I now believe that Einsteinian materialism and "universe as mind" are ALREADY consistent with each other, to a degree I did not even consider when I did not understand the mathematics as well as I do now. Still, even a brief explanation of how this could be does require a little digression and background:
http://drpauljohn.blogspot.com/2017/05/father-of-quantum-computing-writes-on.html
http://drpauljohn.blogspot.com/2017/05/spirit-lessons-from-tlingits-and.html
But what IS Bohm's model, and how does it fit with relativity and quantum mechanics?
When many people talk about "Bohm's model," they are referring either to his earlier work on the "pilot wave" concept (which I attribute more to Louis De Broglie, whom I discussed this with at length years ago; I recently scanned the letters he sent me) or to his later work with Hiley. Hiley has remained active, as Brian Josephson on this list knows very well. If I were Bohm, perhaps I would have even published a short summary list of alternative models like "Bohm 1, Bohm 2" or "Bohm 3," to reduce confusion. Is it possible that some "Bohm's models" are still other models developed by followers of Bohm?
At one time, De Broglie and Bohm hoped that a "pilot wave" formulation of the simple, original nonrelativistic Schrodinger equation, based on a concept of "Q potential," could explain the quantum mechanical behavior of the electron in a way consistent with Einsteinian materialism. (The Copenhagen version of quantum mechanics was not.) But in a paper in the 1970's, I pointed out that this would only work in the general case of N electrons if the Q potential were a function of many dimensions. Thus the Q potential effort ended as a mere complicated reinvention of the "many worlds" or "multiverse" theory of the cosmos, developed by Hugh Everett and John Wheeler (more Princeton here!), and developed much further by David Deutsch of Oxford (the father of digital quantum computing).
I have the impression that Bohm decided to stay with the Q potential kind of approach, and embrace the nonlocality of the many worlds school of thought, while De Broglie himself (and I) looked for another way, trying to resurrect the full original Einstein vision, which is consistent with experiment only if one makes different assumptions about the nature of time and causality. That can be done, and it is not
only a matter of interpretation. It is a matter of testable differences in competing theories. Furthermore, the differences are fully testable in the realm of quantum electrodynamics (QED), which is NOT a complete or fully resolved matter at all.
I remember when I took graduate courses in physics at Harvard, when everyone said that QED was the most successful, fully tested theory in all the history of physics, that it is highly precise in all of its predictions, and that it is a "done deal" in terms of basic physics. People would say "if you want to learn something fundamentally new, don't do QED." They believed that modern electronics and photonics (and phononics etc) "are all just applied QED."
Then I ended up running the research program in the Engineering Directorate of NSF supporting "applied QED" for the electronics and photonics areas, very complex and serious areas full of lots of experimental exploration, and learned more and more from the new community that "No, QED is NOT a done deal. Many, many really fundamental things still need to be done and discovered, though yes computation and approximation theory are part of it." (For example, see my paper at arxiv with Klimeck and Dowling inaugurating the NSF QMHP activity, which ended when I retired in 2015. My opposite number in NSF's DMR division also retired, and Dean Poor of Princeton legitimately wondered what was happening -- to this area, to climate change, to social science, to evolution.... even to NASA!)
I deeply regret not taking the course in quantum optics taught by Glauber at Harvard. I certainly considered it, and wondered what was really behind his door as I walked by it on the way to Schwinger's class. But I did not realize that he was teaching the scalar version of a whole new stream of fundamental mathematics fundamental to Einstein's program, or that the laboratory aspect with lasers would have let me do myself either or both of the fundamental new experiments we need done, to clarify the core issues before us now regarding quantum measurement and how it really works. One of those experiments, the all-angles triphoton experiment, is described in Werbos and Dolmatova (published in Quantum Information Processing, reposted at www.werbos.com/triphoton.pdf). More recently, I came up with a messier but easier design which would require only two entangled photons, which a friend says he will be doing fairly soon.
But where did the pilot waves go? The Q potential... well, that aspect went away, in my view. But De Broglie's core concept of pilot wave
(as in his book with Vigier, which I cite in the recent paper) is a key part of how I make a BRIDGE between the deeper Einsteinian level of reality (which addresses gravity and addresses why particles exist at all) and the level of CORRECTED QED. To describe our mundane level of life, as "shadows in Plato's cave," it is enough to understand corrected QED, which is equivalent to David Deutsch's view BUT WITH A DIFFERENT VERSION OF QUANTUM MEASUREMENT. The pilot wave concept is a crucial piece of how we CONNECT that level of physics and life to a deeper level.. a level which I understand mathematically this week better than I did just a few weeks ago, when I went to Alaska. (No papers yet, only a few entries in my Samsung Galaxy Tab and related thoughts.)
But now, this week, I go back to more mundane things, all in the realm of truly applied QED, true electronic and photonic technology.
One week, one lifetime, at a time.
Best regards,
Paul
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