# Piet Hut: Book Review: The Special Theory of Relativity, by David Bohm

Piet Hut, 1999,   J. of Consc. Stud.6, No. 1, 120-122.

### The Special Theory of Relativity, by David Bohm (1965, 1996: Routledge)

In a dialogue between science and other fields of human knowledge, it is generally taken for granted that we know what science is. The questions are framed in terms of finding bridges between two or more known entities, such as science and art, or science and religion. All effort is then directed towards building the bridge, as if the two sides are granite-like in their givenness. A more promising, but far more difficult approach starts with a scrutiny of each side of the dialogue. Rather than trying to cross the gap by building a bridge, we can explore by descending along the slopes at each side, in search of the bottom of the canyon, where both sides meet naturally.

David Bohm was an explorer of the latter type. He is well-known for his investigations in the structure and interpretation of quantum mechanics, and also for his attempts to engage in open-ended inquiry, through dialogues. Less known are his more general investigations into our scientific view of the world: how it is established, and how it can change over time. In the present book he highlights the role of the scientist, in doing science, while avoiding the complexities and controversies of quantum mechanics.

The main text of the book provides a clearly written introduction to special relativity, as one out of many good books on that topic. The gem that makes this book so valuable, more than thirty years after its publication, is the 46-page appendix "Physics and Perception". Here Bohm presents a highly original view of what it means to look at the world with new eyes. He contrasts the way in which a physicist must learn to switch from Newtonian mechanics to special relativity with the way that a child learns to switch between the various stages of perceptual development, while trying to make sense of the world and his or her own place therein. Most importantly, he shows how the processes of abstraction and perception are far more similar, and at the same time far more interwoven, than we usually think. In the middle of the process of perception, we are continuously abstracting, in order to make any sense at all of what we perceive. And conversely, our very abstract scientific analysis has many elements in common with more mundane forms of every-day perception.

Science is a collective enterprise of making more sense of the world, through a process of finding more accurate laws in specific domains. Bohm characterizes this process as an ongoing series of attempts at finding what is invariant, relative to a suitable domain (involving particular approximations, related to what we choose to focus on). Both in science and in daily life, we are consciously aware of dealing with things', objects of various types. However, when we analyze how we encounter those things and how we interpret their existence and characteristics, we find that we actively have to manufacture our recognition of the objects, through a process of stabilization. What we find, strictly speaking, is a set of invariants. For example, a child learns that an object that disappears behind a screen can re-appear, and that the amount of water in a glass does not depend on the shape of the glass, when it is poured from one glass into another.

Objects, such as tables and chairs, are special examples of such relative invariants. This is, of course, not how we normally describe a chair. We have to train ourselves, to learn to see' that we do not really see a chair, by noticing how we grasp the imputed existence of a chair from our fleeting stream of ever-changing sense impressions. We live our lives in a world of internal maps, constituting our understanding of the structure of the world, and all our sense impressions are forced to fit into those maps. Without a highly sophisticated cognitive map, it would be impossible to recognize even such a simple object as a chair. But since these maps have been established early on in our lives, we have forgotten the processes of map building and maintenance. These processes run in the background, and we are largely unaware of the presence of the maps we rely on. We are lost in the world of our maps, in the belief that they are part and parcel of the real world we live in. While this assumption is highly effective for our every-day habitual actions, it can form a stumbling block when we begin to explore new realms, in search for insights into new things', i.e. new relative invariants.

Bohm considers scientific investigation first and foremost as a mode of extending our perception of the world, in which we are embedded, rather than a mode of obtaining knowledge about the world. The very notion of knowledge of the world' has an absolutist ring to it; by analyzing the parallels between science and perception, the relative nature of our understanding, which is always contextual, is drawn out. On p. 223, he writes about what happens when we see an elliptical image of a disk, and conclude that its intrinsic shape is circular:

. . . one of the basic problems that has to be solved in every act of perception is that of taking into account the special point of view and perspective of the observer. The solution of this problem depends essentially on the use of a number of levels of abstraction, all properly related to each other. Thus a person not only perceives the immediate elliptical appearance of the disk in front of him. He can also perceive the changes in appearance of the disk, which result from certain movements which he himself actively undertakes. From these changes his brain is able to abstract information about his relationship to the disk (e.g., how far away it is). The essential point here is that through many levels of abstraction, all going on simultaneously in the mind, it is possible to perceive not only a projection of the object of interest but also the relationship of the observer to the object in question. From this it is always possible in principle to obtain an invariant notion as to what is actually going on. This is represented in a higher level of abstraction, for example, by imagining space containing the disk and the observer himself, in which both are represented in their proper relationships. When a person says that the object is really circular, he is then evidently not referring to an immediate sensation of the shape of the object but to this extended process of abstraction, the essential results of which are represented in this imagined space, containing both the object and himself.

Bohm analyzes a number of examples, from perception as well as from scientific theory building, while referring to psychologists such as Piaget and Gibson. His main point is that our way of perceiving the world through our sense organs is much closer in character and general structure to what is suggested by relativistic physics than it is to what is suggested by prerelativistic physics. In that way, the example of special relativity can help us to understand perception, and perception in turn can help us to understand the process of theory formation. Bohm concludes, on p. 230:

In science this process [of growth of a fresh understanding] takes place at a very high level of abstraction, on a scale of time involving years. In immediate perception it occurs on a lower level of abstraction, and it is very rapid. In science the process depends strongly on collective work, involving contributions of many people, and in immediate perception it is largely individual. But fundamentally both can be regarded as limiting cases of one over-all process, of a generalized kind of perception, in which no absolute knowledge is to be encountered.

Two lessons can be drawn from Bohm's analysis. The first one applies to all human activities, and concerns our tendency to let the use of abstract maps become so habitual as to hide them completely. These maps effectively prescribe all that can possibly happen, in every condition and domain of experience. In order to find room for new investigations, in a world which seems to lack any extra room, the first step is to analyze how we have come to know our world. By treating our knowledge as a kind of perception, something that is always tentative, we are more likely to find the extra degrees of freedom that are always present, but often deeply hidden.

The second lesson concerns scientific education, both on the professional and popular level. We tend to emphasize the way in which scientific instruments extend our body and sense organs, externally. Rarely do we mention the fact that we have to extend our inner organs of perception and abstraction as well. While the latter is just as fundamental as the former, it is left as a form of tacit knowledge, to be acquired by the student almost as an accident. The result is that scientists are by and large unfamiliar with the very process through which their scientific world view is constructed. The present book forms a good antidote, by inviting us to investigate this process, as an important step along the road towards confronting the question `what is science'.

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