What a difference one letter makes! The two scientists, Nils Bohr and David Bohm, offer an entirely different interpretation of the quantum theory of sub-atomic phenomena. Both accept the fundamental mathematics of the Schrodinger wave equation and its consequences, since this gives a very accurate description of the experimental results; but from there on, their views diverge sharply.
Reading Bohm’s book “The Undivided Universe” is not easy; I only understood parts of it. In any case, here is what I have gleaned so far.
(1) Bohm is trying to construct an ontological and de-terministic interpretation of the observed facts and mathematics, not merely an epistemological and probabilistic approach such as Bohr’s. What this means is that the wave equation is a description of external reality and not only of our knowledge of it, the particle is really there, and the wave packet does not contain only information on probability. Ontology and epistemology coincide in classical physics, but diverge in Bohr’s interpretation of quantum physics; not so in Bohm’s interpretation.
(2) This also means that the uncertainty principle of Heisenberg, according to which we cannot have an exact knowledge of an electron’s position and momentum at the same time, is only a limitation of our knowledge, not of objective external reality. As well, the observer or the measuring instrument does not determine the nature of the event being measured — the event is objectively independent of the act of measurement. There is no collapse of the wave packet.
(3) Bohm achieves a consistent explanation along these lines in a way basically different from De Broglie and Betchov (see my essay The Peak of Non-linearity), who introduce an additional non-linear term into the Schrodinger equation, which can be identified as the particle accompanying the wave. Bohm rejects this approach, as well as Bohr’s idea of complementarity of particle and wave aspects, Heisenberg’s suggestion that the waves represent potentiality or probability of finding the particle there, and von Neumann’s idea that the quantum state continues to exist between measurements (an idea rejected by Bohr).
(4) Instead of all these alternatives, Bohm postulates that the waves carry “active information” which direct the motion of the particle in a way analogous to that in which telegraph messages from shore direct the motion of a ship at sea. The electron particle derives energy from the electro-magnetic field (as the ship does from its own engines), not from its wave packet; the latter only provides the information which regulates the energy as if through a relay system (cf. my essay The Three Essences). There is an additional term in the Schrodinger equation which represents the “quantum potential” which is related to the active information of the wave packet.
(5) If there are two slits ahead instead of one (as in a famous experiment that led to the wave equation), the wave packet “feels” the presence of the second slit and “informs” the electron particle of this fact, causing it to behave differently (cause interference fringes), even though the particle goes only through one of the slits. This “feeling” and “informing” seems to imply that the electron is somehow alive and uses its wave packet as an antenna. It implies, as Bohm himself says, that the electron is not a simple ultimate particle, but that it has an intricate, complex internal structure, such that it can receive something like telegraph messages. If that seems far-fetched, remember the Bohr-Heisenberg paradoxes that it replaces — paradoxes that Einstein could never accept, stating that “God does not play dice with the Universe”. Bohm’s approach seems to imply radical universal vitalism instead. (See my essay Radical Vitalism.)
(6) There is a cost (in credibility) to moving away from Bohr’s wave-particle duality and lack of objective ontology, Heisenberg’s uncertainty, observer involvement, and wave packet collapse through measurement. Bohm has to accept certain other “weird” concepts in exchange. We have already seen the assumption about a living intelligent electron receiving active information from its wave packet; an-other weird concept is “non-locality”, as seen e.g. in the EPR experiment, where two electrons originating from a single point remain “aware” of each other, though they are too far apart to communicate. This is the worst kind of “action at a distance” that was once banned from classical physics, except that Newton’s theory of gravitation and electromagnetic theory as well seemed to defy it. Perhaps this precedent makes non-locality respectable. What, after all, is space? There was no such thing before the Big Bang, and there is probably no such thing at dimensions below 1012. In any case, quantum theory remains “weird”, i.e. different from classical theory, regardless of the interpretation accepted. We only get a choice of which “weirdness” seems preferable.
(7) Bohm also accepts the theory of the implicate order, although it is not clear to me that this follows directly from his alternative quantum model. The explicate order consists of observable phenomena, but underlying this is the implicate order into which the explicate order enfolds and from which it again unfolds. The whole cycle repeats, and this is called the “holomovement”.
(8) The model of this is the hologram, into which at every point is enfolded all the information needed to produce the whole. This “unbroken wholeness” accounts for non-locality. This reminds me of the fact that the whole genome is present in every cell of an organism, i.e. all the information needed to produce the whole organism is embedded (enfolded) in every one of its cells. However, each cell “expresses” (unfolds) a different part of the genome. This is a way of maintaining integration of the whole while the parts differentiate. One can think of an application of this principle to federalist structures in politics, where every level of government is elected directly by the people, the people being analogous to the total genome.
(9) Bohm also postulates ever-higher levels of implicate order; i.e. the first level of implicate order enfolds into the second level one, and so on. This is reminiscent of the physical, etheric, astral etc. levels in esoteric or occult theory. This may seem far-fetched, but I like to point out possible trans-disciplinary connections.
(10) The ink drop experiment, which I am not sure was a real physical experiment or a thought experiment, illustrates the idea of enfolding and unfolding for Bohm, as well (I would add) the idea of the reversibility of processes under certain circumstances. A droplet of coloured ink is placed in a very viscous clear liquid placed between two cylinders which rotate at different speeds. If the outer cylinder has a higher rotational velocity than the inner one, the ink droplet will be drawn out into a thin thread until it becomes invisible; it is then enfolded into the viscous liquid. By turning the cylinders in the opposite direction, the droplet can be restored, however. This is true only if the liquid is so viscous that it prevents mixing by diffusion, and so prevents the entropy law from creating permanent irreversibility.