Dreams of Earth and Sky

by Freeman Dyson

  “Asperger’s syndrome” is an alternative name for the high-functional end of the autistic spectrum. Hans Asperger was an Austrian psychologist who studied children who were socially inept but intellectually sharp. Several parents of my acquaintance are proud to claim that their gifted children “have a touch of Asperger” when the children develop a passion for painting or mathematics. Asperger’s syndrome has become a distinction rather than a disease. If every child who is silent and withdrawn and has an unusual talent has a touch of Asperger, then Dirac certainly had a touch of Asperger. If Asperger’s syndrome is included in the autistic spectrum, then Farmelo is justified in concluding that Dirac was autistic.

  The definition of autism is today based on symptoms that are poorly defined and on medical judgments that are largely subjective. That is why the posthumous diagnosis of Dirac as autistic or nonautistic is a matter of opinion. But in the future, an objective diagnosis may become possible. We have strong evidence that autism is associated with anatomical abnormalities in the brain, and that autism is heritable. When this evidence from neurology and genetics has been consolidated, it is possible that the diagnosis of autism based on symptoms will be replaced by a diagnosis based on the objective observation of brains and genomes. At some time in the future, when the intricacies of brains and genomes are understood in detail, a reliable posthumous diagnosis of Dirac’s personality may become possible, provided that some fragment of tissue carrying his DNA has been preserved.

  Since the era of diagnosis based on DNA has not yet arrived, I base my tentative diagnosis on anecdotal evidence. Two anecdotes in Farmelo’s book strike me as strong evidence that Dirac’s peculiarities had nothing to do with autism. Both episodes occurred before he married Manci and became domesticated. In 1935, when Kapitza and his wife were detained in Russia, their two sons were left behind in England, and the Kapitzas appointed Dirac as legal guardian of the boys. Dirac took care of the boys until they joined their parents in Russia. While the boys were with him, Guy Fawkes Day occurred, the English equivalent of July 4, traditionally celebrated with bonfires and fireworks. Dirac organized a fireworks show for the boys.

  The second anecdote concerns another famous Russian physicist, George Gamow, who was also a close friend of Dirac. Gamow was notorious as a practical joker. He had emigrated from Russia and settled in Washington with his wife. Dirac was traveling in Florida and saw some alligators for sale. He decided to give Gamow a taste of his own medicine, bought a baby alligator, and mailed it anonymously in a parcel to Washington. The joke succeeded even better than Dirac intended. Gamow’s wife opened the parcel, was seriously bitten by the alligator, and accused her husband of perpetrating the joke. Dirac had hit two birds with one stone. He let a month pass before confessing that he was the guilty party. These two stories show us Dirac as he was in his thirties, a young man with a fondness for children and a robust sense of humor, very far from the pathological self-absorption that is the basic symptom of autism.

  The last chapter of Farmelo’s book concerns Dirac’s legacy to later generations. The legacy consists of three parts: first, the laws of nature that Dirac discovered in his wonder years from 1925 to 1933; second, the doctrine of mathematical beauty that he preached for the remaining fifty years of his life; and third, his distaste for philosophical interpretation of his discoveries. For practicing scientists, the chief legacy of Dirac is the starburst of discoveries that he made as a young man. His legacy to nonscientists is not so clear. Farmelo emphasizes the doctrine that he preached later, proclaiming that mathematical beauty is the key to scientific truth. In order to discover the true laws of nature, the searcher after truth should pay more attention to abstract beauty than to practical details. The beauty and simplicity of the laws of nature would be revealed in abstract mathematics. The second legacy is summarized in a statement that Dirac wrote at the end of his life: “If you are receptive and humble, mathematics will lead you by the hand.”

  The doctrine of mathematical beauty is itself beautiful, and there is no doubt that Dirac believed it to be true. But it does not agree well with the historical facts. During the wonder years when he was making his great discoveries, his thinking was more concerned with practical details and less with abstract beauty. And during the long second half of Dirac’s life, when he was preaching the doctrine of mathematical beauty, it did not lead him to important new discoveries.

  During Dirac’s middle years, the grand edifice of modern particle physics was growing up around him, with discoveries of new particles and new symmetries bursting out in rapid succession. Nature was screaming at him to pay attention to her revelations. But his love for abstract beauty told him to stay aloof. He ignored the new discoveries of particles and symmetries, because he judged them to be too complicated, not beautiful enough to be true. Instead of listening to Nature, he was telling Nature how to behave. As a result, the second half of his life was comparatively sterile.

  In addition to the two legacies of discoveries and aesthetic principles, Dirac also left a third legacy, which I consider precious but Farmelo does not. This legacy is Dirac’s refusal to engage in philosophical arguments about the interpretation of quantum mechanics. These philosophical debates raged during his lifetime and have raged even more fiercely after his death. Dirac took no part in these debates and considered them to be meaningless. He said, as Galileo said three hundred years earlier, that mathematics is the language that nature speaks. When expressed in mathematical equations, the laws of quantum mechanics are clear and unambiguous. Confusion arises from misguided attempts to translate the laws from mathematics to human language.

  Human language describes the world of everyday life and lacks the concepts that could describe quantum processes accurately. Dirac said we should stop arguing about words, stay with mathematics, and allow the philosophical fog to blow away. I consider Dirac’s disengagement from verbal disputes about the meaning of quantum mechanics to be an essential part of his legacy. But I am, as usual, in the minority.

  Note added in 2014: In response to this review, I received a number of illuminating letters from friends and relatives of the Dirac family. I encouraged the authors to send copies of their letters to the Dirac archive, which is maintained at Florida State University at Tallahassee.

  *Basic Books, 2009.

  12

  THE CASE FOR FAR-OUT POSSIBILITIES

  SINCE PEOPLE BEGAN to wonder about human destiny, there have always been prophets of hope and prophets of doom. Long ago in Mesopotamia, as recorded in the book of Genesis, Abraham fell on his face and God talked with him, saying:

  Behold, my covenant is with thee, and thou shalt be a father of many nations.… And I will make thee exceeding fruitful, and I will make nations of thee, and kings shall come out of thee. And I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant.

  Abraham was the first prophet of hope in the Western tradition. He set the pattern of our culture. He was a traveler, moving into a new country to take possession of it for his descendants. A little later, other prophets of hope, Gautama Buddha and Lao Tse, started other traditions in other places. Meanwhile, in the West, Jeremiah the prophet of doom raised his voice in Jerusalem against Abraham:

  The word of the Lord came also unto me, saying, thou shalt not take thee a wife, neither shalt thou have sons or daughters in this place. For thus saith the Lord concerning the sons and concerning the daughters that are born in this place, and concerning their mothers that bare them, and concerning their fathers that begat them in this land. They shall die of grievous deaths; they shall not be lamented; neither shall they be buried; but they shall be as dung upon the face of the earth: and they shall be consumed by the sword, and by famine; and their carcasses shall be meat for the fowls of heaven, and for the beasts of the earth.

  Other prophets of doom proclaimed in other traditions the anger of gods and the helplessness of humans. The dialogue between Abraham and Jeremia
h continues today. It is still one of the main themes of our history. So what is new?

  One thing that is new is modern science. Science has not displaced religion as the way most people approach the problems of our destiny, but science allows us all to look at these problems in a new way. Francis Bacon, the major prophet of modern science in the British tradition, did not proclaim the word of the Lord but spoke with his own more modest voice: “If we begin with certainties, we will end in doubt, but if we begin with doubts and bear them patiently, we may end in certainty.”

  Bacon was writing at the beginning of the seventeenth century, when religious wars were raging in Europe, when Pilgrim fathers filled with Abrahamic hopes were building a new world in America, when Puritan divines filled with visions of jeremiad doom were preaching hellfire and damnation. He offered a third alternative to the certainties of heaven and hell: the alternative of patient inquiry. He told us to ask questions instead of proclaiming answers, to collect evidence instead of rushing to judgment, to listen to the voice of nature rather than to the voice of ancient wisdom. Bacon predicted accurately the growth of modern science. In the centuries since he wrote, modern science has transformed the problem of human destiny. Destiny is now no longer an unalterable fate, irreversibly good or evil. Destiny has become a continuing experiment in which we are free to learn from our mistakes.

  In the modern world of life and death to which we all belong, a crucial problem of our destiny is the size of human populations. It seems to be a simple problem. How many people should there be? How many babies should we raise? But modern science has twice transformed the nature of the problem. In the eighteenth century, science started industrial and medical revolutions that caused a rapid growth of populations. In the twentieth century, science started social revolutions that caused an equally rapid decline of birth rates.

  It was easy to understand, as Robert Malthus pointed out in his famous Essay on the Principle of Population in 1798, how new technology had caused population growth that might in turn cause a disproportionate growth of human misery. It is more difficult to understand, in the world of today, how birth rates fell rapidly in large parts of the world while remaining high in others. It appears that birth rates fell sharply for different reasons in different places, in China because of draconian rules imposed by the government, in Europe and America because a large fraction of women became educated and economically independent. Meanwhile, birth rates remain high in Africa and in parts of Asia where societies are maledominated and women are mostly illiterate.

  Three facts emerge clearly from the history of the last three centuries. First, a huge experiment is in progress, exploring various ways of dealing with the problem of population. Second, no central authority is in charge. Third, the result of the experiment is still in doubt. Many kinds of disaster resulting from population explosion or population collapse are still possible. Nevertheless, the results of the experiment up to the present time are encouraging. The disasters predicted by Malthus did not occur. Populations in several parts of the world with different political and ethical traditions were successfully controlled by different methods. It appears to be generally true that rising wealth and communication and education in any society produce a rapid fall in birth rates. This is an experimental conclusion, subject to criticism and correction. It does not tell us that the problem of population is finally solved. It tells us that the solution of the problem is still in our hands, to be explored by continued experiment and by correction of errors.

  When we look to the remote future, the main problem of our destiny will not be the size of populations but their quality. Shall we remain a single species bound together by bonds of family and kinship, or shall we evolve into many diverse species as our vertebrate ancestors did in the past? Either alternative brings losses as well as gains. If we remain single, we lose vast opportunities to explore new ways of living and thinking. We lose the historic power of biological evolution to try out new experiments and to create new designs of body and mind. If we diversify, we lose the brotherhood of man. We lose the shared loyalties and traditions that made us what we are. By separating into alien species, we open endless possibilities of future strife and irreconcilable quarrels.

  Perhaps these dangers can be mitigated if the diversification of human nature is combined with an expansion of our habitat from one planet to a multitude of communities spread out over the universe. Those of us who choose to stay on this planet should remain brothers, while those who choose to experiment with new creative possibilities should move far enough away that the failure of their experiments will not endanger those who stayed at home. The vastness of the universe allows us to dream of an infinite future for humanity, with bodies and minds spreading in space and expanding in quality far beyond anything that we can imagine. That is why David Deutsch gave his book the title The Beginning of Infinity.* The subtitle, “Explanations That Transform the World,” carries the central message of the book. It says that our destiny is to be explainers of the world around us, and explaining is the key to mastery.

  Deutsch has an important message. He writes clearly and thinks wisely. His book could help to push the world toward better ways of dealing with its problems. It is written for concerned citizens and not only for philosophers. I hope many concerned citizens will read it and take its message to heart. Unfortunately, Deutsch is himself a philosopher, with a fondness for abstruse philosophical arguments. Fortunately, he puts his plain language and his abstruse philosophizing into separate chapters. The common reader should skip the technical chapters and pay attention to the others. The difficult chapters 11 and 12, “The Multiverse” and “A Physicist’s History of Bad Philosophy,” ought to have been published as a separate book, addressed to a different audience. They have little connection with the outstandingly lucid chapters 10 and 13, “A Dream of Socrates” and “Choices,” which stand immediately before and after them. The difficult chapters are for readers who share Deutsch’s view of the nature and purpose of philosophy.

  Philosophy can be regarded as a branch of science or as a branch of literature. For Deutsch, philosophy is a collection of explanations and arguments that are either right or wrong. For me, philosophy is a collection of stories. For Deutsch, the only philosopher who deserves unconditional respect is Karl Popper, because he alone asked the right questions and gave them the right answers. For me, the great philosophers are those like Plato and Bertrand Russell who happen to be good writers. In one of his lighter moments Russell expressed a view of philosophy similar to mine: “Science is organized common sense; philosophy is organized piffle.” In my view, Deutsch becomes a true philosopher when he forgets his technical arguments and tells evocative stories.

  Deutsch sums up human destiny in two statements that he displays as inscriptions carved in stone: “problems are inevitable” and “problems are soluble.” His chapter “The Spark” introduces these statements and explains their meaning. They apply to all aspects of human activity, to ethics and law and religion as well as to art and science. In every area, from pure mathematics and logic to war and peace, there are no final solutions and no final impossibilities. He identifies the spark of insight, which gave us a clear view of our infinite future, with the beginning of the British Enlightenment in the seventeenth century. He makes a sharp distinction between the British Enlightenment and the Continental Enlightenment, which arose at the same time in France.

  Both enlightenments began with the insight that problems are soluble. Both of them engaged the most brilliant minds of that age in the solution of practical problems. They diverged because many thinkers of the Continental Enlightenment believed that problems could be finally solved by utopian revolutions, while the British believed that problems were inevitable. According to Deutsch, Bacon transformed the world when he took the long view, foreseeing an infinite process of problem-solving guided by unpredictable successes and failures. Deutsch’s version of history is narrow. It is Whig history, portraying human destiny as a tri
umph of parochial British ideas and institutions.

  Long before Bacon, thinkers in China were taking a long view of history and pushing it along a different path, and Socrates in Greece was teaching us to search for wisdom by asking questions rather than by knowing the answers. Many diverse cultures were converging to the conclusion that humans have a choice. If we want to, we can be the spark, transforming the universe from a purposeless machine into a creative community of living creatures always asking new questions and struggling to find new answers.

  Returning to present-day problems in his chapter “Choices,” Deutsch discusses politics and economics. Two questions have dominated the study of political economy in the past. How should we choose our rulers? And how unequally should we distribute wealth between rich and poor? In recent debates over the choice of rulers, people have usually asked the wrong question. They asked, who are the best rulers? They assumed that if this question were answered, then we should allow the best rulers to rule and the problem of good government would be solved.

  But history taught us long ago that this is the wrong question. There are no best rulers, because power corrupts and circumstances change. Rulers often begin well and then make stupid mistakes. The English civil war between King Charles I and his Parliament demonstrated clearly that the concept of a best ruler was an illusion. The king, claiming to rule by divine right, abused his power flagrantly, and the parliamentary leaders rose in rebellion against him. The Parliament won the war, beheaded the king, and appointed Oliver Cromwell to rule in his place. When Cromwell died, the Parliament decided after all to invite the son of the murdered king back.