"Einstein was very unhappy about this apparent randomness in nature. His views were summed up in his famous phrase, 'God does not play dice'. He seemed to have felt that the uncertainty was only provisional: but that there was an underlying reality, in which particles would have well defined positions and speeds, and would evolve according to deterministic laws, in the spirit of Laplace. This reality might be known to God, but the quantum nature of light would prevent us seeing it, except through a glass darkly."
And a quote from here which describes Einstein's distrust of some of Quantum physics. He in fact did 'not' accept the 'bigger picture'.
"He said it because he found himself in profound disagreement with many of the most outstanding and influential physicists of his time: physicists like Neils Bohr, Werner Heisenberg and Max Born who had adopted what came to be known as the "Copenhagen interpretation" of the then-new field of quantum mechanics.
His disagreements with them were philosophical. Just as he rejected their claim that experimental results in quantum mechanics implied that nothing exists unless it is being observed by a conscious human being, so also he disagreed with their claim that these results implied that the so-called "deterministic" philosophy of Newtonian mechanics was false."
I'm aware of all this, b_sharp. Would you like my "take" on it?
Go for it.
First of all, Hawking’s description of Einstein’s reservations about quantum mechanics is spot-on IMHO. Einstein’s disagreements with Niels Bohr and his group at Copenhagen were philosophical at their root; but from this it doesn’t seem necessary (to me at least) to conclude that Einstein rejected the idea of “the big picture,” or that his own science wasn’t motivated by the search for it. I hope to show in what follows that the contrary was the case.
There are many parts to this, so please bear with me.
First, Einstein was a pivotal figure in the history of science. His General Relativity theory represents the culmination of classical (Newtonian) physics. But at the same time, he himself was a major pioneer (with Max Planck) in the revolutionary new theory that became known as QM. He discovered the light quantum – the photon – in 1905 (for which he received the Nobel prize. Strangely, he was never awarded a Nobel for his work in relativity theory!). The photon seemed to bother the heck out of him; but there it was. Though perhaps “repugnant” to him personally – his preference was to regard light as a continuous waveform, “classical” realist that he was -- his assumption of the quantum nature of light has been fully experimentally validated.
Second, the point about Einstein as a “classical” realist: He fully subscribed to the determinism of Newtonian mechanics that QM was eventually to displace. The underlying assumptions of Newtonian physics:
(1) The physical world is made up of inert and changeless matter, and this matter changes only in terms of location in space;In other words, crudely put, classical theory expects that a tree falling in the forest makes a sound regardless of whether there is an observer around to notice it. This is “the realist view.” And evidently, this was Einstein’s view.(2) the behavior of matter mirrors physical theory — there is a one-to-one correspondence between any given phenomenon and the physical laws that apply to it — and physical theory is inherently mathematical;
(3) matter as the unchanging unit of physical reality can be exhaustively understood by mechanics, or by the applied mathematics of motion; and
(4) As Hawkings said, “particles … have well defined positions and speeds, and … evolve according to deterministic laws, in the spirit of Laplace.”
(5) the mind of the observer is separate from the observed system of matter, and the ontological bridge between the two is physical law and theory. (Nadeau and Kafatos, 1999, as modified by me)
Needless to say, Einstein was disturbed by Bohr’s and Heisenberg’s introduction of the Observer into physical theory. (Indeed, this is probably one of the most “radical” things the theory does.) But one senses that he does not grasp what Bohr means by “the observer” and its role.
He and Bohr were excellent friends; and Einstein liked to twit Bohr about this: “If Neils does not see the moon in the night sky, then for him, the moon does not exist.” IOW, he thinks Bohr is arguing for the introduction of subjectivity into physical science. But Einstein’s little joke is not at all what Bohr intended. All Bohr meant was that if something cannot be observed, then it cannot be described – and science is not about discovering the “how” of nature, let alone the “why”; but only about “what we can say about” nature.
I think Bohr’s point was that if a scientist hasn’t observed a phenomenon, then he cannot say anything about it. The moon is still up there (presumably): It doesn’t depend for its existence on any subjective observation. But its description does so depend. This is the subtle point that Einstein evidently didn’t grasp. Further, Bohr’s idea of the “observer” is intimately related to the idea of direct “measurement.”
A third point is Einstein evidently had a strong distaste for introducing statistical methods into physics (“God does not play dice”). But the need for statistical tools, brilliantly pioneered by Ludwig von Boltzmann in the mid-nineteenth century -- became manifestly evident in the ground-breaking work of Max Planck. Planck’s constant – a vanishingly tiny number (whose effects are not noticed at all in the classical domain of macroscopic nature, wherein the Newtonian laws are the legitimate “king” for all practical purposes and will likely remain so) – is a measure of uncertainty WRT the behavior of phenomena at the quantum level; and where there is uncertainty, the need to resort to statistical methods becomes acute. Einstein was aware of all this, of course. That didn’t necessarily mean that he liked it.
My conjecture: A clue to Einstein’s reservations may be found in his stated desire to “transmute the base wood of matter into the pure marble of geometry.” And this is where I think Einstein was grasping for “the bigger picture”: What he was looking for was an ultimately simple, elegant, single underlying universal principle that would rationalize all of physics, classical and quantum; thus all of the universe. And his suspicion was that such a principle would be found to be a geometrical form. All the pesky untidiness and “strangeness” of QM suggested to him that the Copenhagen circle was definitely on the wrong track. This is where his “realism” crosses over from the Newtonian (and LaPlacean) into the Platonic realism; e.g., into the realm of Plato’s Idea. (I am not alone in thinking that Einstein was a mathematical platonist; and also Gödel, Penrose, Tegmark….)
Fourthly, another key assumption of classical realism is that the universe is inherently “local.” That is to say, all physical causation is the result of the actions of bodies in close proximity to each other. Quantum theory, however, shows that the universe is inherently non-local: Our classical ideas of causation utterly break down in the quantum world. This Einstein would never accept — he dismissed this sort of thing as “spooky action at a distance.”
Fifthly, Einstein and Bohr had radically divergent ideas about epistemology, or the science of “what we know, how we know it, and how do we know we know it.” Einstein was an Aristotelian in this regard: For him, “If two descriptions are mutually exclusive, at least one of them must be wrong” (Aristotle’s Law of the Excluded Middle).
Bohr, on the other hand, insisted that the logical framework of complementarity -- that it is not a question of either/or, but of both -- is useful and necessary when the following conditions are met:
(1) when a theory or entity consists of two individually complete constructs [e.g., is it a particle or a wave?]; (2) when the constructs preclude one another in a description of the unique physical situation to which they both apply [e.g., you can only pick one of the two constructs for study at a single time]; (3) when both [taken together] constitute a complete description of the overall situation.Bohr’s complementarity principle recognizes the inherent uncertainty attending observation of entities at the quantum level, and provides a way to reconcile what appears to be mutually-exclusive aspects thereof. The observer must choose which construct he wishes to observe -- Is it a particle or a wave? – because both cannot be observed at once. Once the choice of observation is made – say, particle – then the waveform temporarily “vanishes.” Similarly, to choose to observe the wave makes the particle construct “vanish.” As Bohr pointed out, regarding the “vanished” quantity, it’s not a matter of what we don’t know, but of what we cannot know, simultaneously, contemporaneously in any experimental setup.
But to have complete knowledge about the total system, information about both of the complementaries – particle and wave – is indispensable. And, as noted, one cannot observe them both together, simultaneously. (This is where the uncertainty principle gets its foot in the door, so to speak.)
“The hard lesson here from the point of view of classical epistemology is that there is no god-like perspective from which we can know physical reality ‘absolutely in itself.’ What we have instead is a mathematical formalism through which we seek to unify experimental arrangements and descriptions of results” (Nadeau and Kafatos, 1999). And probably just as disturbing from Einstein’s point of view, the act of observation itself disturbs the observed object, and thus modifies the total system “on the fly,” as it were.
* * * * * *
Well, that’s the “deep background” of the “dispute” between the two friends, against which to appraise Hawkings’ astute statement that Einstein thought that what the Bohr circle was all about was the overthrow of the “‘deterministic’ philosophy of Newtonian mechanics.” Evidently Bohr didn’t see it that way.
For Bohr, quantum mechanics is not designed to overthrow, nor is it an extension of, classical mechanics. Instead, he viewed classical mechanics as a subset, or approximation that has a limited domain of validity, of a more general physical situation which is comprehensively described by QM.
Bohr often emphasizes that our descriptive apparatus is dominated by the character of our visual experience and that the breakdown in the classical description of reality observed in relativistic and quantum phenomena occurs precisely because we are in these two regions moving out of the range of visualizable experience. (Hooker, 1972)Newtonian mechanics is “king” (as already mentioned) in its domain: the macroworld of nature that falls within the range of direct visualization. Bohr wrote, “Just as relatively theory has taught us that the convenience of distinguishing sharply between space and time rests solely with the smallness of the velocities ordinarily met with compared with the speed of light, we learn from the quantum theory that the appropriateness of our visual space-time descriptions depends entirely on the small value of the quantum of action compared to the actions involved in ordinary sense perception. Indeed, in the description of atomic phenomena, the quantum postulate presents us with the task of developing a ‘complementary’ theory the consistency of which can only be judged by weighing the possibilities of definition and observation.” (quoted in Nadeau and Kafatos, 1999).
As mentioned already, QM is the general case of which classical physics is a special case. And Bohr further thought they fully “corresponded” with one another. Thus, the correspondence principle of QM. Further, Bohr insisted that all descriptions of quantum phenomena be made in the language of Newtonian physics.
...it is imperative to realize that in every account of physical experience one must describe both experimental conditions and observations by the same means of communication as the one used in classical physics. (Bohr, 1958). The decisive point is to recognize that the description of the experimental arrangement and the recording of observations must be given in plain language suitably refined by the usual physical terminology. This is a simple logical demand since by the word “experiment” we can only mean a procedure regarding which we are able to communicate to others what we have done and what we have learnt. (Bohr, 1963)Heisenberg had an ingenious way to show how the correspondence works. I am indebted to the physicist Henry Stapp for his insight into this matter (in his paper, “Quantum Interactive Dualism: An Alternative to Materialism”):
Many of the best mathematical minds of the generation wrestled with [the correspondence] problem, but it was not until 1925 that Werner Heisenberg discovered the amazing and unprecedented solution: the numbers that in classical physics describe the physical properties of a system must be treated [in QM] as mathematical actions (operators) instead of numbers. An essential difference between numbers and actions is that the order in which two numbers are multiplied does not matter -- 2 times 3 is the same as 3 times 2 -- but the order in which two actions are performed can matter. According to the rules discovered by Heisenberg, the difference generated by changing the order in which these actions are applied involves Planck’s constant. In particular, if one takes the equations of quantum mechanics and replaces Planck’s constant everywhere by zero then one recovers the corresponding classical theory. Classical physics thereby becomes an “approximation” to quantum physics, namely the approximation obtained by replacing the true value discovered by Planck by zero.* * * * * *Because Planck’s constant is an extremely tiny number on the scale of human activities, the classical approximation is normally a very good approximation in the realm of phenomena that do not depend upon the details of what is happening at the atomic level.
Well must wrap up, for I’ve already run on too long (and probably exceeded my mandate as well). We have to ask: Why did Einstein reject QM up to his dying breath when he could recognize that all of its features that he found controversial – non-locality, the centrality of the observer, superposition, apparently superluminal velocities, uncertainty and the need for statistical methods – had been repeatedly empirically validated?
My conjecture is that his rejection was essentially “religiously” or spiritually motivated. Not in any sectarian sense, but in the Platonic sense: My suspicion is he received from “The Old One” a vision akin to Plato’s Agathon -- a vision of universal truth, elegance, beauty, simplicity, goodness, and justice – which is essentially a religious vision. It set the course of his lifelong scientific endeavor. On the basis of this vision, QM just had to be ‘wrong.’ To him, QM exemplified none of the expected elements of his own universal vision.
If you think that is far-fetched, b_sharp, then simply consider your own dealings with scripturally-based Christians who may, to you, appear to be hermetically sealed against the reception of new [scientific] ideas, simply because they do not appear to conform with Holy Scripture as they understand it.
Though you are entirely free to disagree with me, I think something along those lines explains Einstein’s lifelong resistance to quantum mechanics.
Thanks for your patience, b_sharp, and for kindly hearing me out.
Best regards….