The discomfort that I feel is associated with the fact that the observed perfect quantum correlations seem to demand something like the "genetic" hypothesis. For me, it is so reasonable to assume that the photons in those experiments carry with them programs, which have been correlated in advance, telling them how to behave. This is so rational that I think that when Einstein saw that, and the others refused to see it, he was the rational man. The other people, although history has justified them, were burying their heads in the sand. I feel that Einstein's intellectual superiority over Bohr, in this instance, was enormous; a vast gulf between the man who saw clearly what was needed, and the obscurantist. So for me, it is a pity that Einstein's idea doesn't work. The reasonable thing just doesn't work.
John Stewart Bell (1928-1990), author of "Bell's Theorem" (or "Bell's Inequality"), quoted in Quantum Profiles, by Jeremy Bernstein [Princeton University Press, 1991], p. 84.
Classic quantum mechanics seems to exhibit some of the characteristics that Immanuel Kant (http://www.friesian.com/kant.htm) described about the relation between phenomenal reality in space and time and things-in-themselves.
As interpreted by Roger Penrose (http://www.friesian.com/penrose.htm), quantum mechanics, first of all, posits a certain metaphysical dualism. In the world as it exists apart from observation, matter and energy consist of waves that are deterministically governed by Schrödinger's Equation. The waves have an undoubted physical reality because of the interference effects that can be observed, and because the three dimensional size of atoms is due to the state of their electrons as three dimensional standing waves -- otherwise there is nothing to "fill the space" of atoms, except particles somehow being everywhere at once, which they can't be because in changing directions to get here and there they would radiate energy. (Fields can be said to fill the space, but this only postpones the problem, since fields in quantum mechanics are exchanges of virtual particles.) On the other hand, the square of the wave function gives a probability distribution for where discrete particles may be found once the wave function is collapsed by an act of observation. The wave function thus contains the sum of all possible states of a system until it is observed. This produces the paradox of Schrödinger's Cat, who is both alive and dead at the same time, in just that proportion as each state is probable.
The act of observation, which collapses the wave function, is conformable to the Kantian act of synthesis, by which phenomenal objects are introduced into consciousness and subjected to the categories of the understanding. Niels Bohr's own Principle of Complementarity was that matter and energy could exhibit wave properties, or particle properties, but never both at the same time. If what Kantian consciousness requires is discrete actual things in space and time, this is exactly what is delivered in quantum mechanics: Bohr stipulated that observers and their equipment would never be subject to quantum mechanical probability effects. Around us, for Bohr, we maintain a little, discrete, actual, Classical universe.
Kant did not view things-in-themselves as containing the sum of all possibilities, and phenomena all actualities; but this duality is conformable to Kant's metaphysics as to none other. As a contribution to the metaphysics of possibility, the quantum mechanical wave function can easily be seen as complementary to Kant's idea of things-in-themselves, where various kinds of things can happen (like free will) that are not comprehensible in terms of phenomenal reality. Kant would just have to allow that characteristics of physical reality can intrude some depth into things-in-themselves, which he would not have considered -- though we can also handle this by positing an intermediate level of reality, between true unconditioned things-in-themselves and true discrete phenomenal objects. The wave function straddles the classic Kantian boundary, sharing some properties with phenomena, others with things-in-themselves.
Thus, where Kant would have considered all of phenomena governed by determinism, we now see the wave function as deterministic, while the collapse of waves into particles is random. Although chance in quantum mechanics has often been argued as allowing for free will, a free cause is still a very different thing from a random cause, which doesn't need mind or self or intention. Moral freedom is thus still left among things-in-themselves.
Kant's idea that space and time do not exist among things-in-themselves has been curiously affirmed by Relativity and quantum mechanics. In Relativity, time simply ceases to pass at the velocity of light: for photons that have travelled to us as part of the Cosmic Background Radiation, time has stood still for most of the history of the universe. On the other hand, quantum mechanics now posits "non-locality," i.e. physical distances, and so the limitation of the velocity of light in Relativity, don't seem to exist. This means that although time may apply to the wave function, space may not. The full empirical reality of space is only found among discrete particles and objects.
This curious result is the consequence of the Einstein-Podolsky-Rosen (EPR) Paradox, which was intended by Einstein as a reductio ad absurdum of quantum mechanics. If, for instance, a positron and an election are both created from an energetic photon, the conservation of angular momentum requires that one be spinning one way, and the other the other. But the complementary spins are equally probably for each particle. Thus, in quantum mechanical terms, the wave functions of each particle separate without a discrete state being determined. The particles might then separate to even cosmological distances, but as soon as the spin of one particle is observed, the other particle must have the opposite spin, which means that the wave function has collapsed across those cosmological distances and caused the other particle to assume a predictable spin. If this occurs instantaneously, it would violate the limitation of the velocity of light in Special Relativity.
This has now been shown to actually occur on the basis of Bell's Theorem (from John Bell, 1928-1990), meaning that Quantum Mechanics does violate Special Relativity by allowing instantaneous interactions across even cosmological distances. However, once observed, processes must still obey Special Relativity and the limitations of spatial distance, creating the kind of duality described by Kant. Bell himself found this result disturbing, but to Kant it would fit in with his own theory that space is only imposed by the representation of phenomenal objects.
Einstein always objected to quantum mechanics because his metaphysical realism recoiled from the idea that observation would create a different kind of reality than what existed independently. At first Heisenberg's Uncertainty Principle could be interpreted as meaning that the act of observation would physically disturb a system in an ordinary and realistic way, but then it soon became evident that strange things were allowed to happen in the wave function that not only could not be observed but could not even be conceived in ordinary and realistic ways. Reality existed in a different way while under observation than it did in itself.
Now, the original philosophical theory which advocated something of the sort, that observation (the synthesis of objects in consciousness) imposes certain forms and rules before things can appear as phenomenal objects, was indeed that of Kant. Einstein and all his contemporaries must have been aware that there was something familiar about the emerging quantum world. The outright anti-realism of Bohr's Copenhagen Interpretation, although the focus of conflict, was only one historical possibility. Kant's empirical realism and transcendental idealism was another. But I have not noticed Kant receiving any kind of notice or credit for a theory that would address some of the paradoxes produced by quantum mechanics, denying the independence of physical reality from the presence of human consciousness. Since nothing is so characteristic of Kantian philosophy than that principle, perhaps it is only a matter of time before philosophers pull their heads out of the "post-modernist" hole in the ground and pay attention. Physicists, of course, don't have to care, unless they hear the call of metaphysics as well as physics.
Since this page was originally posted, one of the most notable responses was from a correspondent who was indignant that the views of David Bohm (1917-1992) and other alternative theories about quantum mechanics were not presented. The purpose of this site, however, is to develop and apply Kantian and Friesian philosophy, and not necessarily to examine every other theory that other people may find important or definitive. Since Kant's was the original philosophical theory in which the observer imposes conditions on the nature of objects, it is arguably an interpretation with historical and conceptual priority. Thus, since it usually is not given much credit for this, it deserves some extra attention, as provided here.
Now, however, some additional comment may be in order, after I was struck by the treatment of recent developments in quantum mechanics in a centennial article in the February 2001 Scientific American, "100 Years of Quantum Mysteries," by Max Tegmark and the historic physicist (e.g. a teacher of Richard Feynman (http://www.friesian.com/feynman.htm)) John Archibald Wheeler (pp.68-75). According to Tegmark and Wheeler, the recent trend is to try and preserve the determinism of the wave function, substituting for discrete particles more localized waves whose interference or interaction has been aborted by "decoherence," in which superpositions of wave functions are "dissipated" by "tiny interactions with the surrounding environment." This is the complete opposite of an approach like that of Bohm, who, like Einstein, believed that discrete particles with definite locations are always present. That would now be called a "hidden variable" theory, i.e. that the quantities for the location of the particles are there, but are hidden from observation. It is frequently said that the success of Bell's Theorem rules out all hidden variable theories, but Bohm's seems to be an exception to this. Bohm postulated a new force, the "quantum potential," to account for the wave-like and interference effects between particles. Later, Bohm assimilated the quantum potential into a larger theory of the "implicate order," in which a hidden order, unity, and wholeness underlies all reality and accounts for all quantum effects, including the non-locality evident in the result of Bell's Theorem.
Now, it is a respectable and venerable practice in physics to postulate new forces. For such theories to gain popularity, however, there is a great deal to overcome, not the least of which is just Ockham's Razor. If the main reason to have the "quantum potential" is just to preserve a realism and determinism about particles, then most physicists are not going to get too excited. The "implicate order," on the other hand, is a large dose of metaphysics. Just as that may make the theory more attractive to theosophists, it is going to turn off mainstream physics, which is probably why Bohm's name is not even mentioned in Tegmark and Wheeler's article. The implication there is that the hidden variable theories are finished and that the hope for a deterministic quantum mechanics will be found in dealing with the wave function, eliminating discrete particles altogether.
However, it is evident in the article's own terms that even "decoherence" doesn't help much with the basic quantum mechanical dilemmas about possibility. Thus, although it does not occur in the main text, the insert on page 73 contains the telling admission, "Decoherence does not completely eliminate the need for an interpretation such as many-worlds or Copenhagen." Indeed. This is because even the "dissipation" of superpositions still leaves alternative "classical" probabilities. The alternative possibilities are either going to have to separate into different worlds, or they are going to have to collapse into just one particle. The insert on page 74 extends the decoherence of different worlds to the mental states of the observer, who can be both happy and sad about the fall of a playing card without the happy or the sad person being aware of the other. This does not seem to help much in eliminating the strangeness of quantum mechanics or the vast metaphysical overkill of the "many worlds" interpretation. If the wave function collapses into one particle, or one mental state, however, then this maintains the metaphysical dualism between wave function and particle that both Bohm and the decoherentists want to eliminate.
If dualism survives, and a dose of metaphysics is in order, then Kant still provides a good alternative. Indeed, Kantian things-in-themselves can provide a modest "undivided wholeness" not unlike Bohm's theory, though with no more than is necessary to explain non-locality, as considered above.