PROFILES OF THE FUTURE: An inquiry into the Limits of the Possible, by Arthur C. Clarke, Harper and Row, 234 pp., $3.95.

In the time of Clarence Day's father, it was literally possible for a man to be born and to die in essentially the same world. To be sure, technological advances were made within one man's lifetime, but they were not generally frequent or far-reaching enough to drastically alter a person's way of life. Yet today, with the furious pace of scientific development, men must expect to leave a world significantly different from that which they entered.

As the tempo of change has increased, prophecy has become an increasingly hazardous undertaking. Most recent predictions in retrospect seem unaccountably timid; one has the feeling that the prophets of late have failed to recognize the most fundamental aspect of scientific endeavor today--its incredible, accelerating rate of discovery and accomplishment.

In Profiles of the Future, Arthur C. Clarke, the noted British science popularizer, has carefully avoided timidity. Looking a mere fifty years ahead, Clark foresees immortality, artificial life, interstellar probes and meetings with extra-terrestrial intelligence. "Impossible" is a rare word in his book.

To be fair it should be said that Clarke is not always serious about his predictions. Much of his discussion has strong overtones of science fiction, a form of writing familiar to him. (He has to date published 17 volumes of science fiction.) But his outlook is thoughtfully sober on many topics, and, as he is quick to point out, he has already had some success in the prophecy business: as early as 1945, he predicted the launching of a worldwide network of communications satellites.

Clarke's particular specialty is space flight, and his thoughts on the subject are the least whimsical and most interesting part of the book. He anticipates the obsolescence of the rocket as the basic space vehicle, for several reasons: they are incredibly complex and awkward; they are inefficient and inordinately expensive; they are unbearably noisy and unpleasant; and finally they are unsafe. He points out that soon the rockets on Cape Canaveral will be holding the energy equivalent of atomic bomb in their tanks, and that a devastating accident is an eventually certainty. Some quieter, safer propellant system must be found.

Although his suggested alternatives are vague, he is able to fall back on a proven axiom of science--that in the absence of theoretical barriers, if a development is needed, someone will sooner or later solve the problem. Scientists from Newton to Salk have expressed this sentiment, and not out of false modesty; one has only to look at the number of simultaneous discoveries in the history of science to see the trend of inevitability, in both theoretical and applied endeavor. Thus both Neptune, and the theory of evolution were simultaneously and independently discovered.

Problems of Space

He sees problems in space development. One particularly interesting discussion concerns the use of satellite-transmitted, world-wide TV as the most far-reaching, effective propaganda device in history. A country in possession of a satellite relay system could saturate the globe with information of any kind; anyone who has seen people mesmerized by TV, not only in the U.S. but in the underdeveloped nations as well, can appreciate the potential of such an extensive and persuasive media.

And yet he has overestimated the value of the communications satellite in many areas, particularly instantaneous transmission of live events. It may well be, as he predicts, that a satellite network will be fully operational by the 1964 Olympic Games at Tokyo, but who in New York will stay up until 3 to watch an event held at noon in Japan? Recording the event on tape and playing it at a more suitable time seems a much better approach.

Clarke's inquiry into the ramifications of space itself is provoking. He observes that men in the past have thought of space as a wide field for colonization, an outlet for the population explosion, with exploration leading to an eventual space empire. But even with better space vehicles, travel will never be cheap; certainly the over-crowding of the earth cannot be significantly alleviated in this way. Furthermore, the limitation imposed by the speed of light itself means that communication, even between planets, will be difficult. There will be a three minute transit time for messages from Mars to the Earth; clearly a conversation in the earthly sense is impossible. Even between the earth and nearby moon, there will be a two and a half-second delay. At interstellar distances, communications will require years to reach their destinations. Travel will be infinitely slower, and anyone who sets out to visit a star cannot expect his children, or probably his children's children, to live to see the end of the journey. Clearly an empire is out of the question.

Clarke might well have limited himself to space flight; instead he has chosen to discuss possible developments in a myriad of scientific fields. One reason the book is so interesting is its scope, and any scientist reading it must acknowledge the author's skill as a science popularizer. His predictions are filled with easy but remarkably correct explanations of current work in various fields. In simplifying essential concepts, he consistently avoids that major pitfall of the popularizer, losing the basic meaning of the concepts to the field. Were he any simpler, he would be inaccurate; if he were more technical, he would bore and confuse most of his readers. Clarke has drawn a fine and sure line between the two hazards of his work.