Stephen Hawking tells us in his new book that following a tracheotomy in 1985, he lost his voice. Before the operation he'd had great difficulty speaking: Close associates, family and friends "translated" what he said for those not accustomed to his speech. Understandably, his sudden inability to communicate was devastating.
Fortunately, a California computer expert heard of his problem and built a synthetic voice for him. With the new system he was able to communicate better than he had before: He wrote two books and gave both popular and scientific lectures.
"This synthesizer," he writes in "Black Holes and Baby Universes," "is by far the best I have heard because it varies the intonation and doesn't speak like a Dalek. The only trouble is that it gives me an American accent. However, by now I identify with its voice. I would not want to change even if I were offered a British-sounding voice. I would feel I had become a different person."
Dr. Hawking's ready acceptance of his new American "voice" is certainly characteristic of his extraordinary ability to adapt to the motor neuron disease that has afflicted him since he was a young man. But it illustrates a more general characteristic of the ways in which we can adapt to physical handicaps that might befall us in a lifetime.
Not very long ago, John Hull in "Touching the Rock: An Experience of Blindness" mentioned that when he became blind in middle age, he soon lost the ability to visualize people whom he knew and had continued to meet since his blindness. He could no longer imagine what he looked like in a mirror.
But he could still visualize people whom he no longer encountered since he had been stricken. Like Dr. Hawking, he adapted to his disability, not by forgetting his former self (he knew he used to see, as Dr. Hawking knows he had a British voice) but by transforming that experience into something new.
Dr. Hawking now identifies with his American voice, as formerly he had identified with his British voice. In fact, like Dr. Hawking and Mr. Hull, we are all constantly reworking our past experiences, constantly transforming our memories, our understanding of ourselves and others in the light of our new experiences. We remember people and places differently in new contexts and in later periods of time. We identify with our "new" voices.
These considerations are not unrelated to the broader themes about the origins of the universe that are the central concern of this marvelous collection of essays. Some of them are reprints of articles that have appeared elsewhere, and while much of their content will be familiar to readers of Dr. Hawking's "A Brief History of Time," his unpretentious and insightful ventures into the purely philosophical realms of determinism and free will are sure to intrigue and fascinate anew.
As Dr. Hawking notes, the extraordinary success of physics in uncovering the laws of nature and explaining the evolution of the universe means that in some very broad sense we also know the equations that determine the functioning of our minds and bodies, and hence determine our thoughts and actions. But should this give rise to the fear that this is the end of our free will?
Dr. Hawking reassures us that there is no cause for worry. The equations cannot be solved. Furthermore, if we could predict our every thought and action, we would upset the very system that we claim determines our actions. "I have noticed that even people who claim that everything is predestined and that we can do nothing to change it look before they cross the road," he writes.
All of this assumes that we might soon have a complete physical theory. For the moment we don't. The dynamic laws of physics can explain the evolution of the universe going back about 15 billion years. Then they "break down." Just what this means might be best understood by analogy with the already mentioned ways in which our memory lets us adapt to the constant changes in our lives, both traumatic and trivial.
Memory, like the laws of physics, is dynamic; it is a constantly evolving relation between our past and our present. One cannot exist without the other. We cannot remember the initial moments of our lives, let alone our early years, because memory (and hence knowledge in general) is not possible without a certain minimal acquisition of experience. What is mysterious is how that "past," that initial phase of knowledge, is created -- how our early experiences are acquired so that memory and knowledge can begin to function.
The laws that govern that acquisition are different from the laws that govern mature thought and action, just as the laws that governed the first moments of the universe are different from the laws of physics that have governed the subsequent evolving universe we know today. We cannot know an instant of time directly; we can only know it in relation to past experience.
It could be that what limits our ability to know the laws of physics, which are dynamic descriptions of the material world, limits human knowledge in general. We may never know how it all began, if indeed it did begin at some specific point in time. Dr. Hawking is optimistic that there might be a way out of this impasse, and his discussion of these questions is wonderfully clear and fascinating.
The frank essays on his physical disabilities add a human face to this abstract discussion and are certainly not irrelevant to the larger questions raised. For, as I have said, the reasons Dr. Hawking can accept his American voice as his own have to do with the nature of knowledge, with the basis of our understanding of the universe. It is only by understanding the limits of our knowledge that we can come to grips with what we can and cannot know about the universe.
Title: "Black Holes and Baby Universes, and Other Essays"
Author: Stephen Hawking
Length, price: 182 pages, $21.95