Strings, Physics, & Visual Intelligence
I recently purchased 3 books which I am concurrently reading:

The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next by Lee Smolin
The Comprehensible Cosmos: Where Do the Laws of Physics Come From? by Victor J. Stenger
Visual Intelligence: How We Create What We See by Donald D. Hoffman

Although Hoffman's book might appear to be on a subject unrelated to the others, that turns out not to be the case. The reason goes back to my maxim: biology trumps physics. What I mean by this is that we cannot understand the nature of the physical world until we first understand the nature of understanding. What are we doing when we make observations of the physical world and devise scientific laws or theories? Although published nearly 10 years ago, Visual Intelligence is the best introduction I have found to the subject.

I had a hard time deciding between Lee Smolin's The Trouble with Physics and another recent book which also derides String Theory: Not Even Wrong: The Failure of String Theory And the Search for Unity in Physical Law by Peter Woit. In the end I chose Smolin's more for budgetary reasons than anything else.

Victor J. Stenger is better known for the recent bestseller God: the Failed Hypothesis (perhaps the best of the recent bestsellers by atheists). I was more interested in spending my good money on Stenger's earlier work because it appears to do an excellent job of explaining 20th century physics & cosmology "without mathematical details so that the general reader can at least get a sense of the gigantic conceptual developments that took place over the last century." [p. 13] Still, Stenger is very aware that

No matter how valiantly scientists and science writers may work to express modern models in the vernacular, precise mathematical descriptions and their associated logical deductions can never be satisfactorily reduced to everyday language. Describing physical models in words is like describing great music in words. Just as you have to listen to music to appreciate it, you have to read the equations of physics to grasp their meaning. This has resulted in a sharp division between "knows" and "know-nots," drawn at such a high level of knowledge that it excludes the great bulk of humanity—from the person in the street to otherwise highly educated academics who have neglected their mathematical studies. Even many PhD physicists and astronomers whose specialties are in fields other than particle physics and cosmology do not fully appreciate these new developments because they are cast in a language that only the experts speak. [p. 13]

Stenger attempts to bridge this gap by use of a 130-page mathematical supplement, so that "anyone who has taken the major courses in a four-year curriculum of undergraduate physics, chemistry, engineering or mathematics should have no trouble" understanding "what has been one of the greatest achievements in human history." [p. 13]

But make no mistake, Stenger understands (as does Stephen Hawking and many other physicists) that physical theories are only useful models, not necessarily accurate descriptions of physical reality. He writes,

Perhaps we will never comprehend the true structure of reality. And perhaps we should not care. We have a model that fits the data, which is all we need for any conceivable application, save philosophical or theological discourse. [p. 188]

Stenger rejects, therefore, the notion that there exists a model or set of explanations which constitute "physical laws" which (in the words of Kip Thorne) "force the Universe to behave the way it does". [Thone as quoted on p. 8] Stenger explains,

You might think of science as a 100 megapixel digital camera taking pictures of whatever reality is out there, compared to drawing a picture in the dirt with a stick. The scientific picture gives a far better representation of that reality, but we still must be careful not to equate the image with reality. [p. 11]

Which brings us to Visual Intelligence and the biology of vision (really the biology of all phenomenal experiences), for Hoffman's book explains the scientific basis behind Stenger's refusal to equate physical models with reality. Analyzing numerous optical illusions, Hoffman establishes 35 "rules" which the human brain uses to create everything we see, including the experience of color, texture, lines, shape, objects and even their motions. The rules stem from what Hoffman describes as "the fundamental problem of vision" from the brain's perspective: the pattern, intensity and frequency of photons interacting with the light-sensitive rod and cone cells of the retina have "countless possible interpretations." The brain uses rules to create a visual field that is self-consistent and useful -- not (importantly) because that visual field is an accurate depiction of physical reality but because it is a useful model for an organism to exist in and manipulate that reality. This visual model (which I like to call a simulacrum) is created by the visual cortex of the brain.

Hoffman also references the experiences of patients with damage to various parts of the visual cortex in order to build his case. For example, damage to an area called V5 will prevent the perception of motion. Victims with such damage see object without a problem, for instance a car on a road. But they will suddenly see the car in a new location on the road and will insist that the car never moved from one spot to the next. All they perceive is a sudden "jump" to a new position. As it turns out the effect can be induced using what is called transcranial magnetic stimulation (TMS) which temporarily impairs the functioning of V5. Hoffman explains,

The results with TMS on V5 are quite specific. Motion is impaired but not, for instance, color. And if TMS is applied to V5 on just the left side of the brain, then the subject loses motion on just the right half of the visual field. Converse, if TMS is applied to V5 on the just the right side of the brain, then the subject loses motion on just the left half of the visual field. [p. 141]

Likewise, damage to another part of the visual cortex, the lingual and fusiform gyri, causes loss of color vision. If damaged only in one hemisphere of the brain, the loss of color only occurs in half of the visual field.

Hoffman is careful to make a distinction between the "phenomenal" world which the brain creates (and which constitutes our experiences) and what he calls the "relational" world (which Stenger calls "physical reality" and Kant called the "noumenon"). In essence, Hoffman demonstrates that the brain creates visual, tactile, and auditory experiences to "model" this unknown reality in a useful way, just as scientists use instruments and mathematical formula to create useful scientific models of this same unknown reality. "The main difference," he writes, "is that the constructions of scientists are done consciously, but those of your visual intelligence are done, for the most part, unconsciously." [p. xii]

The key point, and it applies to vision models as much as it applies to scientific models, is that the models

...need not resemble the relational realm to be well adapted, they need only be a useful guide for behavior. The icons on your computer screen are a useful guide for behavior toward your computer, but those icons don't resemble the circuits and software that ultimately determine how well adapted your behaviors are. Indeed, the icons are a useful guide to behavior precisely because they don't resemble circuits and software. Circuits and software are extremely complex, and if your icons resembled them it would take you forever to get anything done on your computer. your behavior would be less adapted, not more. [p. 198]

Still, Hoffman considers the objection that "when I see a snake slithering toward me in the grass, then I would be a fool not to think that there really is a snake, and I would be a fool not to get out of the way." [p. 198] "Granted," he responds,

when you see snakes there are snakes, and you must take them seriously. Similarly, when you see a trash can icon on your computer screen, there really is a trash can icon, and when you see a document icon representing the text file you've been editing for the last five hours, there really is a document icon. And you must take these icons seriously. If you drag that document icon into that trash icon then you'll lose your last five hours of work. That's a serious consequence. To say that experiences provide a systematic but arbitrary guide to the relational realm is not to deny that experiences are real and must be taken seriously. But they don't entail that anything in the relational realm resembles a snake, just as a trash can icon doesn't entail that circuits and software resemble a trash can.   

Neither biology nor quantum theory dictates the nature of the relational realm. Nor does any other science. Each studies certain phenomena, and describes these by precise theories. In no case do the phenomena or the theories dictate the nature of the relational realm. We might hope that the theories of science will converge to a true theory of the relational realm. This is the hope of scientific realism. But it's a hope as yet unrealized, and a hope that cannot be proved true.

So this is a small sample of what happens when we peek behind the icons, when we ask what else there might be in addition to our perceptual constructions. We find a myriad of fascinating questions. We find that we've entered the province of philosophy and religion. Because the phenomenal and relational realms need not resemble each other, because their relationship is arbitrary and systematic, the tools of science can help us guess at the nature of the relational realm, but might never dictate a final verdict. [p. 199]

In fact, however, there certain things we can say definitively about the relational realm. The most important observation is that our bodies can interact with it. Whatever photons "really are", we nevertheless know that they interact with 11-cis retinal in the photosensitive cells of the retina. And this tells us something truly important: it tells us that the relational realm, reality, Kant's noumenon -- whatever one chooses to call it -- is not something which is spiritual or God-like. Rather, it must be bodily or physical in some sense. Stenger calls it "physical reality" and that seems entirely appropriate to me.

So I recommend these three books. But read Visual Intelligence first, for it provides the biological framework upon which all our scientific endeavor hangs.