Chapter Three

OUT OF THE CLASSICAL ORDER

Much of twentieth century physics is an interaction with and a move away from classical physics. Bohm is no exception. His emphases or points of disagreement, on the other hand, sometimes differ from those of other physicists in this era. This chapter will trace several of the differences between quantum and classical physics. It will look especially at the differences between classical physics, the usual quantum theory, and Bohm's version of quantum theory. It will also focus on Bohm's notion of wholeness, that everything connects with everything else.

Classical physics builds on basic ideas used since the days of Copernicus, Kepler, and Galileo. The physics of Newton and the philosophy of Descartes made the ideas famous. One of them is that reality is out on display. In principle, no part of it is in hiding. A superhuman intelligence could take all the world in at once. The Cartesian view also assumes the universe and anything in it consists of independent parts. These move in a vacuum or a void or, at their smallest, are particles with a position but no volume. They are like the points on a line.<123> These parts can interact as if they were in a mechanical device, that is, with "pushes and pulls."

Another characteristic of classical physics is an absolute and universal time independent of space. It describes space by using Cartesian co-ordinates. Hence, Euclidean geometry was a key for developing the language that describes the order, as Bohm calls it, of classical physics.<124>

Classical physics says that to understand something one only need know the positions of its parts at successive moments. Classical laws describe its movement in relation to all the other objects in the universe. They determine precisely what is going to happen to it. The only uncertain factors are the initial velocities and positions of its parts. Knowing these, one can predict its future course and thereby understand it.<125>

A break from the classical idea of order came with Einstein's theory of Special Relativity. He took the speed of light as an absolute not possible for any object. It is like the horizon which we can, of course, never reach. Though we try to move toward it, we never come any closer. Similarly, though we increase our speed toward that of a light ray, we will never reach its speed. It will always remain the same fixed speed relative to us. Einstein's theory also introduces the radical idea that the rate time passes is relative to the observer. It is not, as in Newtonian theory, an absolute upon which all observers would agree. The passage of time depends on the speed at which the measuring device is travelling. These two ideas of Special Relativity called into question several classical beliefs.<126>

NONLOCALITY

The EPR Experiment and Nonlocality

Besides relativity, the other arm of modern physics is quantum theory. It is also at points different from classical physics.<127>

One of the significant and novel features of quantum theory for Bohm appears in the Einstein-Podolsky-Rosen (or EPR) paradox.<128> It is a continuing theme throughout his writings. In 1935, Einstein, Boris Podolsky and Nathan Rosen published an article introducing their paradox to the world - it has continued to make waves ever since. Bohm helped develop it further in 1951.<129> This imaginary experiment suggests the existence of simultaneous correlated events that do not physically interact with each other and are some distance apart.<130> The events appear connected.

A simplified version of the EPR experiment involves a particle horizontally entering an experimental device. It has the properties that it is not spinning and can be split in half. It is split and the halves head off at 45 degrees either side of the horizontal, with equal but opposite spins. The total spin must be zero by the conservation of spin at the point at which the parent split. When the two halves are some distance apart, one half has its spin changed. Simultaneously, according to ordinary quantum physics, the spin of the other half changes so the conservation of spin holds. What tells the half particle its sibling has changed spin? Does a signal or causal connection travel between them?

It is usual to say there is a correlation between the two simultaneous events in the EPR experiment. There is a difference between there being a correlation and a connection between them. Connection suggests something connects them. Correlation suggests a mutual relation between them. It happens that, on changing one, the other simultaneously changes. Correlation is not a step toward explaining the simultaneous events; connection is.

If there were a signal or causal connection between the two EPR events, it would have to travel at a speed faster than light's to make them simultaneous. According to Einstein's relativity theory, signals do not travel faster than light. Nothing can. This is one of Einstein's assumptions, called locality or the "principle of local causes." A causal influence cannot travel faster than the speed of light between objects not otherwise connected to each other. What happens in one place has nothing to do with what happens at the same moment at some distant place.<131> Bell defines locality as:<132>

the idea that what you do has consequences only nearby, and that any consequences at a distant place will be weaker and will arrive there only after the time permitted by the velocity of light. Locality is the idea that consequences propagate continuously, that they don't leap over distances.

The EPR experiment can suggest a connecting signal that travels faster than light. What else could account for the immediate correlation between the spins of the two particles? Thus, for Einstein, the experiment, based as it is on the usual quantum theory, contradicted locality. He disliked this, writing that physics should be "free from spooky actions from a distance." Locality for him is an "absolutely inevitable requirement for any reasonable physical theory." Quantum theory, he thought, must be wrong.<133>

Unlike Einstein, the Birkbeck School does not interpret the EPR result as contradicting relativity.<134> Its approach does not suggest a faster-than-light connecting signal transferred in a physical medium. It can say this even though it rejects locality. What it says is that the quantum potential underlies simultaneous but distant events in a way that unifies them. The quantum potential contains and carries instantaneous information about the whole environment. Thus it influences the outcome of all events, correlating those separated in space and time. There is no direct causal connection between them; one event does not itself influence another.<135>

Another of Einstein's beliefs is classical realism: objects like particles have classical properties. They always have them (as opposed to the belief that they can sometimes also be waves).<136> Classical realism begins to sound like Bohm's hidden variables. That is not surprising. Einstein suggested hidden variables as a way to resolve the EPR problem with quantum theory and rephrase it to his satisfaction. Since the hidden variables would underlie the existence and behaviors of both particles in the experiment, they could make the simultaneous spin change. It is like pushing one button to produce two effects.

The Birkbeck physicists interpret the EPR result as representing an essential new feature, nonlocality, in the quantum world. For them, quantum physics is a guide toward a new non-classical order for physics.<137> This is different from Einstein's reaction. They thus endorse some of his ideas and reject others. He was a local classical realist and they are nonlocal classical realists: they believe in nonlocal, noncausal, instantaneous connections.<138>

Nonlocality is the opposite to locality and means there can be instantaneous causal influences between objects some distance from each other. (Bohm's nonlocality does not suppose the instantaneous connections are causal.) It is a central topic throughout the remainder of this discussion on Bohm, physics, and religion. It means something can instantaneously affect something else that is not within its immediate area.

Hiley provides historical background to nonlocality. Physicists hesitate to consider it because Western philosophy and science say locality is the only rational option. Physics from Newton through Maxwell to the relativity of Einstein depends on it. Some think Newton would like nonlocality because it is like the attraction of gravity. The latter is, after all, a type of action-at-a-distance. Under gravity, objects affect each other over large distances and without any normal physical connection between them. However, Hiley points out, Newton thought a nonlocal connection absurd. Only the supernatural can transcend time and space.<139>

Using the word nonlocality for the EPR experiment, as the Birkbeck physicists do, is an interpretation of its results. The experiment shows that, when you affect something, instantaneously something else happens some distance away. There is a correlation between them. Nonlocality says it is the change in the first object that somehow causes the change in the second. The word causes is the interpretation the idea of nonlocality introduces. In many respects it is like the word connection.

Some people try to find a mechanism to explain or describe the causal influence in the nonlocality. It could be a normal physical connection, one travelling below, at or perhaps above the speed of light. It could be an abnormal one not accepted by physics. Such thoughts are not in the experiment itself. They are part of trying to understand it.

The questions of locality versus nonlocality and the definition of nonlocality, nevertheless, often arise in the context of the EPR experiment. The writings of the Birkbeck School are examples of this. In fact, they usually use the word connection rather than correlation. With it, the public interest arouses from its slumber. This is sensation.

Performing an EPR Experiment

For many years the EPR experiment existed only in the imaginations of physicists. Experimental evidence hinting at nonlocality did exist in 1957. The unambiguous carrying out of an EPR experiment had to wait until the 1980s.

In a series of articles starting in 1959, Bohm and Yakir Aharonov apply hidden variables theory to the EPR paradox. They also discuss testing it, look at what it implies, and come up with the Aharonov-Bohm (or AB) effect.<140> The original AB effect concerns electrically charged particles moving where there are no electromagnetic forces. The particles behave in a manner not before thought possible. The AB effect now has a more general use developed from its original context.<141> It shows clearly that nonlocal quantum-level phenomena violate our classical ideas. Since we usually use the language of classical physics, it dominates our instinctive thinking. "We are, therefore, surprised by the AB effect," write Bohm and Hiley. We "forget that all quantum effects present us with an entirely novel situation."<142>

Like other parts of Bohm's earlier work, the AB effect is still a lively issue.<143> There is experimental support for it in specific circumstances. It may also occur in several other situations and have practical implications.<144>

Bell aroused the most recent interest in actually performing an EPR experiment. In a paper published in 1964, he develops a precise and mathematical distinction between the experimental results of the two types of theories. One is classical and assumes locality. It takes the properties of a system to be independent of those some distance from it. The other supports the nonlocal correlation, at least at the quantum level, of systems a long way apart.<145> His theorem gives a mathematical inequality. If quantum theory has the locality of classical physics, there is a limit on the number of pairs of particles with a certain property. Experiments can detect this number. To exceed this limit and thus to break Bell's inequality will mean quantum theory does not have a simple classical locality. Einstein would then be wrong.<146>

It turns out that experimental results (Alain Aspect is in particular associated with this work) do violate the inequality. In so doing, they confirm quantum correlations over distances up to twenty-six meters and perhaps up to thirty meters. They disprove theories that assume local classical realism.<147> Researchers also plan more experimental work on this question, while others still dispute the validity of Aspect's work.<148>

The Significance of the EPR Experiment

The results of the EPR experiments uphold quantum physics. They say a quantum theory cannot have both locality and classical realism. In doing so, they challenge our usual understandings of space, time and matter.<149> "As physicists we have learned to live with this [experiment], but we have never really come to terms with it." So conclude F.A.M. Frescura and Hiley.<150> John Clauser and Abner Shimony think similarly. "Either one must totally abandon the realistic philosophy of most working scientists, or dramatically revise our concept of space-time."<151> We have to abandon either classical realism or locality.

Speculation runs wild, despite warnings by people like Peter Hodgson against drawing philosophical conclusions from the experiments.<152> There are many conflicting approaches and interpretations.<153>

Bohm's physics agrees with the EPR experiments. It also provides a way of coming to terms with and understanding the results. To do this, it adopts a particular understanding of nonlocality and keeps classical realism. So it gives up locality and defies common sense.<154> (Why should Bohm make these choices? Probably because they reflect his metaphysical beliefs - a matter which later chapters will address.)

Several physicists follow Bohm. Jean-Pierre Vigier considers the "only way out" of the EPR paradox is in the direction of hidden variables.<155> Mattuck lists reasons the hidden variables theories have merit:<156>

First, such models can yield agreement with quantum physics. Second, they can solve the quantum measurement problem. Third, history shows us that it is risky to reject theories on the grounds that they defy "common-sense." Fourth, these models may reflect a [basic], inescapable nonlocality in nature itself.

Bohm has a following for reasons such as these.

This is not where Mattuck stops. For him, Bohm's nonlocal hidden variables theories "obviously cannot cure nonlocality since they have the disease themselves."<157> Jean-Marc Lévy-Leblond writes that the predictions of the usual quantum theory and the hidden variables theories are different. We can check them. He also qualifies the type of hidden variables theories he would consider. He wants to exclude thoseexhibiting "rather weird nonlocal features." Such qualities "would plague them with...problems even worse than the ones they [try] to solve."<158>

Nonlocality is not universally acceptable. It defies common sense. Most physicists prefer to follow Bohr by giving up classical realism and retaining locality. Thus, the EPR experiments may not mean Bohm is right. They may not mean nonlocality is the correct idea to adopt.<159>

A more conservative approach may win over radicals such as Bohm. One comes from Itamar Pitowsky. Despite important reservations over his work, it is interesting. He claims the EPR experiments only point to a problem with the theory of probability used in quantum physics. Changes to this theory allow him to sidestep Bell's theorem. Then he develops a hidden variables theory that preserves locality.<160> Another conservative approach holds EPR correlations to be primitive givens like uncertainty is in the Copenhagen interpretation. We cannot in principle explain them.<161>

There are other approaches that agree with and try to explain the experiments. In varying degrees they appear to contradict such acceptable ideas as locality and challenge common sense. T.M. Helliwell and D.A. Konkowski ask about influences travelling faster than the speed of light.<162> Could there be a relativity-disobedient faster-than-light "elaborate signalling mechanism" between the two particles in the experiment?<163> Alternatively, do the particles somehow know what is going on in each other? An "unattractive proposition," Hiley thinks.<164> Jack Sarfatti asks if a faster-than-light transfer of information without signals connects immediately the two particles.<165>

Shimony suggests a property called passion. It allows the instantaneous matching of the behaviors of two particles far apart. It does this without them interacting via any forces classical physics knows about and without faster-than-light speeds. There is some form of communication that does not involve information passing as we know it. Vigier replies: "Passion without interaction isn't satisfying."<166>

There are many interpretations of the EPR experiments' success in supporting quantum theory.<167> It is a subject that has raised a considerable amount of interest and dispute theoretically and experimentally.<168>

Bohm and Hiley leave us with a warning. We may want to adopt the Birkbeck School's approach and go on to see nonlocality in all situations. We may want to think of everything connected to everything else regardless of their separations in time and space. The evidence, however, does not support doing this. The connection between objects at the quantum level is in certain circumstances, for example "over relatively short distances for simple systems." It can also appear in complex systems and over somewhat longer distances with the temperature near absolute zero. Thus, breaking systems into independent subsystems as required by classical physics is often acceptable. Bohm and Hiley believe "nonlocality will only reveal itself in very subtle ways." They want to explore "the precise conditions under which such effects appear."<169>

BOHR AND BOHM

Bohr is one of the founders of quantum physics whose name has arisen several times in the discussions so far. There are two attitudes Bohm's writings take toward his work. One is positive and supports the wholeness emphasis of Bohr. The other is negative and says the usual or Copenhagen interpretation of quantum theory is in places incorrect. Bohm wants to take Bohr's wholeness idea further than did Bohr. He would like, for instance, to replace quantum theory's concern for locality with an acceptance of nonlocality. Bohm wants Bohr's usual interpretation to move further out of the classical order than it has, at least on this issue.

Another revolution of quantum theory besides the EPR correlations is the uncertainty principle. Bohr's understanding of the principle has become the key for many physicists' approach to quantum theory. Bohm sees it as still too caught up in the language of classical physics.

The uncertainty principle emphasizes to Bohr the link between the observed object, the observer, and the observing apparatus (as an extension of the observer). A related term is the quantum principle, referring to the idea that the observer and the observed are not distinct.

Wheeler tells how the quantum principle comes from the uncertainty principle. "To observe even so [small] an object as an electron we have to...insert a measuring device. We can insert a device to measure position or insert a device to measure" another property. However, installing one prevents inserting the other. We have to decide which one we will measure. "Whichever it is, it has an unpredictable effect on the future of that electron." To that extent it changes "the future of the universe....We changed it."

The observer and the observed have, in the words of Wheeler, "a tight and totally unexpected [link]." The old word observer needs crossing out and replacing by the new word participant. The quantum principle says we are dealing with a universe in which we participate in some strange way. We have no choice. Demolished is "the once-held view that the universe sits safely `out there.'" We do not observe what goes on in the world "from behind a foot-thick slab of plate glass." We always become involved in what goes on.<170> Hiley rephrases Wheeler. We can no longer gaze at nature through a glass window. We have "to break the window to get involved."<171>

Physics and other languages assumed before quantum theory that separately existing objects make up the world. The interactions of these objects with each other follow well-defined laws. Bohr realized this does not happen in the quantum context; one cannot separate the observed object from the observing apparatus. No observed properties arise from the object alone. It is like "a blind man tapping out the boundaries of a room." In his hand is a rod that is either very flexible or very loosely held. The room's outline is unclear to him "because he cannot separate the effects of the room from the effects produced by the flexible rod itself."<172> This inability to separate the observer and the observed is what the uncertainty principle emphasizes.

Bohr inspired Bohm.<173> For Bohm, the quantum principle and Bohr's uncertainty principle are basic. Quantum theory links the observer and the observed. This is a form of wholeness. On the other hand, Bohr also wants locality, suggesting an independence of distant objects. Bohm wants a nonlocality that suggests everything relates to everything else. There are differences in the thinking of the two physicists.<174>

The differences emerge in the way the two think about language.Bohr insists only ordinary language can describe a quantum-level experiment. It may need refining by the ideas and language of classical physics, making it a generalized form of classical theory. For Bohr, ordinary language is the only unconfused way to describe a quantum experiment.<175>

Bohm does not agree. He develops a language for describing quantum-level events that is unique to it and inconsistent with ordinary language. Bohr's approach treats the results of a quantum experiment as objects he can take out of the context of the experiment. This violates the wholeness notion - in this case the whole experiment. Having taken the results out of their context, Bohr uses mathematics to relate them to natural laws. Again this is independent of the experiment itself and breaks the wholeness, Bohm says.<176>

There is a second and related difference between Bohr and Bohm. Physics has two languages, a formal and an informal one. The formal is the mathematical theory. The informal includes the words used to speak about the mathematics and to do such matters as describe experiments. Bohr accepts for the quantum context a classical informal language for such things as particles, potential, field, etc. The formal mathematical theory may change and it obviously is different from classical physics. The informal verbal language must remain much the same. On the other hand, Bohm carries the change over to the informal language. The new view of reality coming with quantum theory is different from that of classical physics. It causes a basic shift in metaphysics.<177> We cannot hide in classical concepts for meeting and grasping the significance of such ideas as the connection of everything at the quantum level.<178>

There may be nothing rigid or necessary about classical or common-sense language anyway. Bohm, for instance, questions whether the idea of an object is part of what we perceive. Perhaps it is a tool we use to organize our perceptions. Perhaps environmental conditioning and training have made us regard the object idea as obvious and therefore basic.<179>

Bohm wishes to follow Bohr's wholeness logic further than is usual. He even wants to look at the common metaphysics of our culture and to apply wholeness to all experience. He calls for "a movement in which physicists freely explore novel forms of language." It should consider "Bohr's very significant insights." It should not remain fixed to classical language.<180> The hidden variables/quantum potential approach - far from being a retreat into classical physics based on determinism - is part of this movement. As we shall see in the next chapter, Bohm goes even further.

QUANTUM THEORY AND GENERAL RELATIVITY

Quantum theory suggests to Bohm the need for a new description than classical physics'. It must be one that moves beyond separating the observed object from the observing instrument. The conditions for the experiment and the meaning of its results must form a whole. Dividing it into independent parts is now irrelevant. To Bohm, quantum theory also suggests nonlocal connections at the quantum level. These are part of how the Birkbeck physicists view quantum theory's idea of undivided wholeness. They have developed a theory based on them.<181>

Besides wanting to emphasize nonlocality, they want to reconcile the general relativity and quantum theories.

Einstein tried to develop a unified field theory to bring together many separate theories of physics. Its base was to be the mathematics of fields, also the basis of general relativity.

Undivided wholeness is a characteristic of general relativity's field theory. It says the whole universe is a single field that does not divide into separate fields. Further, it is basic. Particles are approximations of it. There is no break or division anywhere, contrary to the Cartesian separation of the universe into disconnected parts.

Both general relativity and quantum theory share the idea of undivided wholeness. The above wholeness ideas in Einstein's theories receive Bohm's support. When elaborated, however, the order of general relativity turns out to be classical. General relativity assumes all events are the interaction within the space-time continuum of fields and objects. This is what Bohm does not support. The continuum is the wrong idea. For space-time it associates a number with each of its points. Movement is a succession of static forms, like the frames of a motion picture. This needs the ideas of both separateness and locality, unlike the order of quantum theory. The two theories understand wholeness differently.<182>

It is little wonder, says Bohm in his evaluation, that no unified field theory has resulted. There is so far no satisfactory way to unite into one theory the two giants of contemporary physics, general relativity and quantum theory. Physicists have been trying to adapt into the wholeness ideas of general relativity the older continuum idea of the world as points without any volume. The lack of success, he continues, is because the two approaches are incompatible. Einstein's field approach fails because space-time is continuous and connected.<183>

There is a second aspect of relativity theory besides the continuum idea that Bohm thinks does not fit the quantum context. It is the idea of a signal. A key for relativity theory is communication between points via signals travelling at the speed of light. It is, for instance, the basis for calculating the relative speeds of different observers. A signal implies there is a store of information in each region. Each store must be independent of and different from that in any other region. This idea, Bohm suggests, conflicts with quantum theory's nonlocality which says the stores connect with each other. He wants to drop the notion of a signal from relativity while retaining many of its other aspects. He wants to enrich our concepts of space and time while staying in harmony with the spirit of relativity.<184>

That is not the end of the disagreements, either. The usual approach to quantum physics in its turn conflicts with the type of indivisible wholeness in general relativity. At the time of observation, the quantum state of the observed object interacts with that of the observing apparatus. When there is no observation going on, the quantum states of the two systems are independent. This undermines the wholeness. Bohm wants to surrender this role of the quantum state, and thereby remove the problem.<185>

Quantum theory and general relativity conflict at certain key points. Bohm therefore chooses between the respective emphases of the two theories, retaining some and discarding others.<186> For instance, he supports the type of undivided wholeness found in nonlocality and in the quantum principle. Since this type conflicts with that of general relativity theory, he wants to change the general relativity type. Why does he not try to change the undivided wholeness in quantum theory instead? Such a question may mean these disagreements are not be the sole reasons for his taking the path he does. He appears to have other motivations.<187>

The Birkbeck physicists seek the reign of a particular type of undivided wholeness in the theories of physics.<188> To meet this challenge, they want to replace the mathematical model of a continuum for space-time.<189> They look to Wheeler who introduces in his penetrating yet speculative manner the idea of a pregeometry. This is a more primitive structure that underlies both general relativity and quantum theory.<190> He asks for a new starting point, one not based on a geometry such as the continuum. The replacement geometry will come from the pregeometry.

To discover the nature of the pregeometry is the challenge Wheeler raises. It is the one to which Bohm, Hiley and their colleagues of the Birkbeck School are responding. For them the holomovement is the pregeometry.<191>