THE POSTWAR YEARS were marked by great advances in many areas of pure science. It was as if young (and not so young) scientists who had been longing to work in the field were trying to make up for lost time. One of them was Freeman Dyson, whose name is now known to all theoretical physicists.

In a fascinating chapter of Disturbing the Universe, entitled "Scientific Apprenticeship," Dyson recounts how he began his life in science under the guidance of the outstanding physicist and teacher, Hans Bethe. He recalls the relaxed atmosphere of American universities, which astonished him by comparison with his native England. There were invaluable sessions with his professor over lunch in the cafeteria and an uninterrupted, exhausting nine months spent working at his desk. Dyson soon turned out to be one of the first to tackle the basic problem of quantum field theory. His work in this area earned him early and deserved praise. Subsequently, Dyson made contributions to diverse fields -- from nuclear physics to rocket technology and astrophysics. Now, he has written a book of philosophical recollections.

Fundamental questions of philosophy and ethics are brilliantly discussed in this book, especially the ethics of science and weaponry, of corresponding disarmament, the principal problems of technological progress and the impending spread -- inevitable, Dyson feels -- of our civilization into space. One may argue with the author, sometimes disagree with him, sometimes even consider him too naive; but he is always consistent, logical and thoroughly honest. There are people who consider deliberations on abstract ideas or on the too-distant future as simply a waste of time. Such people should not pick up Dyson's book -- they will toss it aside with a contemptuous sneer as they would toss aside, for example, the speculative works of rocket pioneer Kostantin Tsiolkovsky. But people with a different perspective will read it with unflagging interest.

The book is written in the form of recollections, spare but pithy stories of those ethical, scientific and practical problems encountered by the author; about his thoughts, doubts and mistakes; the people he worked with or met with, or simply saw. Among these people are Hans Bethe and Richard Feynman, Edward Teller and Robert Oppenheimer, George Meany and Martin Luther King. Their portraits are accurate and benevolent. Even for such people as Oppenheimer and Teller, about whom volumes have been written, Dyson adds to our understanding and unprejudiced evaluation of their motives and actions in the tragic, contradictory climate of world confrontation and moral doubts. The memoir part of the book is vividly written and contains some little-known facts which will appeal to a wide readership. Dyson assumes no previous scientific knowledge on the part of his readers.

To give a general flavor of Dyson's opinions, I'll quote a few of his observations: "Bomber Command was an early example of the new evil that science and technology have added to the old evils of soldiering," he writes in a chapter called "The Children's Crusade," where he talks about his work in the RAF Bomber Command, his moral doubts, and the bureaucratic obtuseness and inertia resulting in the deaths of numerous crews.

"Somewhere between the gospel of nonviolence and the strategy of Mutual Assured Destruction there must be a middle ground on which reasonable people can stand, a ground which allows killing in self-defense but forbids the purposeless massacre of innocents," he writes in the chapter, "The Ethics of Defense." With all my heart and soul I support this thesis -- but I feel it is both an inadequate general principle for making decisions under the concrete, contradictory conditions of global confrontation and an inadequate personal position for real influence on world events. In this same chapter, Dyson supports George Kennan in his call for a rejection of the principle of "first-strike nuclear weapons: as amoral, and -- under Western conditions -- leading to dangerous complacency with regard to conventional weapons. I can't help agreeing with this position. I have always spoken out for parity of forces in all basic types of weapons, and at all points of confrontation. Only from such an initial position is fruitful discussion of disarmament problems possible.

Digressing from the text of Dyson's book, but not its spirit, I wish here to express my support of the SALT II treaty, but only under terms that allow for the elimination of weak points in the American system of strategic weapons. Particularly necessary is the building of more powerful rockets and the development of mobile systems. Once the U.S. has thus achieved parity with the Soviet Union, and with SALT II behind us, the superpowers can proceed to SALT III and a significant reduction of thermonuclear armaments. This, together with rejection of the "first-strike" principle, will diminish the danger of the destruction of civilization in a thermonuclear war.

Again in Dyson's chapter on "The Ethics of Defense," we read: "In the long run, the survival of human society on this planet requires that one of two things happens. Either we establish some kind of world government with a monopoly of military power. Or we achieve a stable division of the world into independent sovereign states, with the armed force of each state strictly confined to the mission of defending its own territory." Dyson definitely prefers the second alternative. In many other chapters, Dyson speaks of human striving toward diversity as one of the bases of civilization, as the most important, foremost spiritual requirement of man. (In particular, he is against the introduction of a universal language). Although I agree with the author in his defense of diversity (pluralism) in all areas of human activity -- ideology, culture, politics, economics -- I have grave doubts about the stability he assumes would result from an arms balance among a few states or groups of states, regardless of their official position on nonaggression. The temptation to break the peace can turn out to be too great, and the consequences for all humanity are too tragic. For this reason, although entertaining considerable doubts, I am for the first alternative -- world government -- at least for the distant future.

Questions of the ethics of science and progress fill much of the book. The author, in the course of his work, encountered many real, acute problems of scientific ethics. With great sincerity, he speaks of his successes and failures, his doubts and mistakes. These parts of the book, based on his personal experience, are among the most interesting. I read them with close attention, involuntarily drawing parallels with episodes in my own life.

For Dyson, there is no doubt that human civilization will go into space. It will go not as part of the struggle with impending overpopulation -- this problem must be resolved on earth -- but to find new possibilities for diversifying life, a principle to which the author accords especial significance. We shall go into space to improve conditions of life on earth using the resources of the cosmos, and to ensure our civilization's invulnerability to possible death from war or political, ecological, or astrophysical catastrophe.

When speaking of progress, Dyson makes a distinction between two types of technology: "gray" technology, based chiefly on the achievements of physics and engineering, and alien to the natural environment, and "green" technology, based to a much greater degree on the achievements of biology, imitating living nature and harmoniously integrating itself into the natural environment. The author believes that the future belongs to "green" technology (I refer you to the book for specific examples). But Dyson (and I am very glad of this) doesn't throw out "gray" technology, for it is a necessary means (temporary in his opinion) for a rapid solution of some of the most pressing problems of progress and well-being.

Dyson also reflects on the use of nuclear explosions in astronautics; the dangers of homemade atom bombs and terrorism; the feasibility of mastering space through private enterprise, in the style of the American pioneers; the basic philosophical questions of the meaning of life, freedom and necessity, and the singleness of cosmic purpose. All are brilliantly explored and illuminated.

Freeman Dyson's book will, without doubt, be read with interest and profit both by those of experience and by the young.