Richard P. Feynman
Richard P. Feynman; drawing by David Levine

Great scientists come in two varieties, which Isaiah Berlin, quoting the seventh-century-BC poet Archilochus, called foxes and hedgehogs. Foxes know many tricks, hedgehogs only one. Foxes are interested in everything, and move easily from one problem to another. Hedgehogs are interested only in a few problems which they consider fundamental, and stick with the same problems for years or decades. Most of the great discoveries are made by hedgehogs, most of the little discoveries by foxes. Science needs both hedgehogs and foxes for its healthy growth, hedgehogs to dig deep into the nature of things, foxes to explore the complicated details of our marvelous universe. Albert Einstein was a hedgehog; Richard Feynman was a fox.

Many readers of The New York Review of Books are more likely to have encountered Feynman as a story-teller, for example in his book Surely You’re Joking, Mr. Feynman!,1 than as a scientist. Not many are likely to have read his great textbook The Feynman Lectures on Physics,2 which was a best seller among physicists but was not intended for the general public. Now we have a collection of his letters, selected and edited by his daughter, Michelle. The letters do not tell us much about his science. For readers who are not scientists, it is important to understand that foxes may be as creative as hedgehogs. Feynman happened to be young at a time when there were great opportunities for foxes. The hedgehogs, Einstein and his followers at the beginning of the twentieth century, had dug deep and found new foundations for physics. When Feynman came onto the scene in the middle of the century, the foundations were firm and the universe was wide open for foxes to explore.

One of the few letters in the collection that discusses Feynman’s science was written to his former student Koichi Mano. It describes the fox’s way of working:

I have worked on innumerable problems that you would call humble, but which I enjoyed and felt very good about because I sometimes could partially succeed…. The development of shock waves in explosions. The design of a neutron counter…. General theory of how to fold paper to make a certain kind of child’s toy (called flexagons). The energy levels in the light nuclei. The theory of turbulence (I have spent several years on it without success). Plus all the “grander” problems of quantum theory.

No problem is too small or too trivial if we can really do something about it.

“The ‘grander’ problems of quantum theory” were only one item in a long list of Feynman’s activities.

The phrase “the ‘grander’ problems of quantum theory” refers to the great work for which he received a Nobel Prize in 1965: inventing the pictorial view of nature which he called “the space-time approach.” This work began in 1947 as a modest enterprise, to calculate accurately the fine details of the hydrogen atom for comparison with the findings of some new experiments that had been done at Columbia University. To do the calculation, Feynman invented a new way of describing quantum processes, using pictorial diagrams instead of equations to represent interacting particles. The “Feynman Diagrams” that he invented for a particular calculation caused a revolution in physics. The diagrams were not only a useful tool for calculation but a new way of understanding nature. Feynman’s basic idea was simple and general. If we want to calculate a quantum process, all we need to do is to draw stylized pictures of all the interactions that can happen, calculate a number corresponding to each picture by following some simple rules, and then add the numbers together. So a quantum process is just a bundle of pictures, each of them describing a possible way in which the process can happen.

Feynman’s diagrams gave us a simple visual representation of quantum processes not only for hydrogen atoms but for everything else in the universe. Within twenty years after they were invented, these diagrams became the working language of particle physicists all over the world. It is difficult now to imagine how we used to think about fields and particles before we had this language. A new book by the MIT historian David Kaiser, Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics,3 gives a lively account of the spread of the diagrams, describing how they were transmitted around the world. The diagrams spread like a flu epidemic. Each new generation of young scientists became infected with the Feynman disease and then infected others with whom they came into personal contact. The Feynman epidemic lasted longer than a flu epidemic, because the incubation period was measured in years rather than in days. Many of the older scientists remained immune, but their influence waned as the new language became universal.


After Feynman’s work on the diagrams was done, a year went by before it was published. He was willing and eager to share his ideas in conversation with anyone who would listen, but he found the job of writing a formal paper distasteful and postponed it as long as he could. His seminal paper, “Space-Time Approach to Quantum Electrodynamics,”4 might never have been written if he had not gone to Pittsburgh to stay for a few days with his friends Bert and Mulaika Corben. While he was in the Corbens’ house, they urged him to sit down and write the paper, and he made all kinds of excuses to avoid doing it. Mulaika, who was a liberated woman with a forceful personality, decided that drastic measures were needed. She was one of the few people who could stand up to Feynman in a contest of wills. She locked him in his room and refused to let him out until the paper was finished. That is the story that Mulaika told me afterward. Like other Feynman stories, it may have been embellished in the telling, but to anyone who knew both Mulaika and Feynman it has the ring of truth.

People who knew Feynman as a friend and colleague were astonished when this collection of his letters appeared. We never thought of him as a letter writer. He was famous as a great scientist and a great communicator, but his way of communicating with the public was by talking rather than writing. He talked in a racy and informal style, and claimed to be incapable of writing grammatical English. His many books were not written by him but transcribed and edited by others from recordings of his talks. The technical books were records of his classroom lectures, and the popular books were records of his stories. He preferred to publish his scientific discoveries in lectures rather than in papers.

This book now reveals that Feynman was, like that other great communicator Ronald Reagan, secretly writing personal letters to a great variety of people. Few of the letters are to his professional colleagues. Many of them are to his family, and many are to people he did not know and never met, answering letters that they wrote to him with questions about science. In spite of his pretense of being illiterate, the letters are written in lucid and grammatical English. They rarely mention his work as a creative scientist. They say nothing about his current research. In these letters we see Feynman as a teacher. He spent much of his life teaching, and he threw himself into teaching as passionately as he threw himself into research. He wrote these letters because he wanted to help anyone who sincerely tried to understand. The letters that he preferred to answer were those which posed problems that he could explain in simple language. The problems were usually elementary, and Feynman’s answers were pitched at a level that his correspondent could understand. He was not trying to be clever. His purpose was to be clear.

Every one of the letters is personal. He responded to people’s personal needs as well as to their questions. As an example of his personal response, here is the last paragraph of the letter to Koichi Mano which I have already quoted. Koichi was unhappy with his life as a scientist because he was not working on fundamental problems. Feynman replies:

You say you are a nameless man. You are not to your wife and to your child. You will not long remain so to your immediate colleagues if you can answer their simple questions when they come into your office. You are not nameless to me. Do not remain nameless to yourself—it is too sad a way to be. Know your place in the world and evaluate yourself fairly, not in terms of the naïve ideals of your own youth, nor in terms of what you erroneously imagine your teacher’s ideals are.

Best of luck and happiness.


Richard P. Feynman

Michelle Feynman added some brief comments to the letters and an introduction describing what it was like to be Feynman’s daughter. She was as surprised as everyone else when she discovered the letters and started to read them sixteen years after his death. For sixteen years they had remained hidden in filing cabinets in the archives of the California Institute of Technology, interspersed with masses of technical papers and lecture notes. As soon as she had read them, she decided that they should be shared with the world. They show a new side of Feynman. The public had seen him before as a great scientist and as a famous clown. A week after I first met him at Cornell University in 1947, I described him in a letter to my parents as “half genius and half buffoon.” Here in the letters he is neither genius nor buffoon, but a wise counselor, interested in all kinds of people, answering their questions, and trying to help them as best he can.


Michelle’s introduction ends with a note that she found with the letters in the archive. Feynman wrote it for his acceptance speech at the Nobel Prize banquet in Stockholm. Before he went to Sweden, when the award of his Nobel Prize was first announced, he made disparaging remarks about the prize and about the formal ceremonies that he would have to endure in Stockholm. He said that he had made up his mind to refuse the prize, until his wife told him that refusing it would bring him even more unwelcome publicity than accepting it. He detested formal ceremonies, and he especially detested the snobbery associated with kings and queens and royal palaces. But then, after he went to Stockholm and experienced the warmth of a Swedish welcome, he wrote a note that is as close as he ever came to expressing his emotions in public. He describes how the prize had led to a deluge of messages:

Reports of fathers turning excitedly with newspapers in hand to wives; of daughters running up and down the apartment house ringing neighbors’ door bells with news; victorious cries of “I told you so” by those having no technical knowledge—their successful prediction being based on faith alone; from friends, from relatives, from students, from former teachers, from scientific colleagues, from total strangers….

In each I saw the same two common elements. I saw in each, joy; and I saw affection (you see, whatever modesty I may have had has been completely swept away in recent days).

The Prize was a signal to permit them to express, and me to learn about, their feelings….

For this, I thank Alfred Nobel and the many who worked so hard to carry out his wishes in this particular way.

And so, you Swedish people, with your honors, and your trumpets, and your king—forgive me. For I understand at last—such things provide entrance to the heart. Used by a wise and peaceful people they can generate good feeling, even love, among men, even in lands far beyond your own. For that lesson, I thank you.

The title of this book is taken from a letter that Feynman wrote for the California State Curriculum Commission, in which he appraised the science textbooks to be used in elementary schools. His son, Carl, was then three years old, due to go to elementary school three years later and learn from the textbooks. Feynman spent much time and effort reading textbooks and pointing out their deficiencies. He also examined the teachers’ manuals that came with the textbooks. The manuals were supposed to explain the material in the textbooks so that teachers could teach it intelligently. Feynman was especially critical of the manuals. In response to one series of books and manuals, he wrote:

Fair. A spotty mixture of good and poor.

In 1st grade, simple clear experiments on condensation, etc., but most of the stuff on animals is how they differ in superficial ways (nothing on how they grow, eggs, babies, etc.)

In 5th grade, chemistry and sound is good and clear, but material on weather and electricity are not very good. In particular, in both these parts (weather and electricity) the teacher’s manual doesn’t realize the possibilities of correct answers different from the expected ones and the teacher instruction is not enough to enable her to deal with perfectly reasonable deviations from the beaten track. Also, in these sections, difficult experiments are suggested which may not work out easily as expected, but the teacher is not given clues that this might happen or what to do about it.

He was particularly concerned that teachers using the manuals might penalize children who came up with original ways of solving problems. This actually happened many years later when Michelle was in high school and was penalized for going off the beaten track to solve an algebra problem. When Feynman went to the school to complain, the teacher accused him of knowing nothing about math. After that, Michelle stayed home to study algebra with her father, and only went to school to take exams.

Michelle was the younger of two children, doted on by her father, loving and admiring him in return. Her brother, Carl, was closer to him intellectually, sharing his interests in science and computers. Michelle describes how she tagged along silently on long walks while her father and Carl talked shop. He once complained to me about Carl:

I always thought I was a good father, being proud of both my kids and not trying to push them into any particular direction. I did not want them to be professors like me. I would be just as happy if they were truck drivers or ballet dancers, provided they really enjoyed what they were doing. But then they always find a way to hit back at you. My son Carl for instance. He is a student at MIT and what does he want to do? He wants to be a God-damned philosopher.

Feynman admired people with practical skills and had no use for philosophers. Fortunately Carl’s affair with philosophy was short-lived. He soon returned to computer science, a field in which he could joyfully share technical tricks and ideas with his father.

It would be easy to fill a review with quotations from the letters. At the beginning there are letters from Feynman to his parents, including a highly nontrivial arithmetical puzzle involving long division that he sent to his father when he was twenty-one years old. His father was a traveling salesman with a passion for science but without any scientific training. That puzzle must have been part of a continuing exchange of puzzles and ideas between father and son. Many years later he wrote about his father:

He told me fascinating things about the stars, numbers, electricity…. Before I could talk he was already interesting me in mathematical designs made with blocks. So I have always been a scientist. I have always enjoyed it, and thank him for this great gift to me.

After the family letters, there is a collection of letters between Feynman and his first wife, Arline, describing day by day their doomed and difficult life through the three years between their marriage and her death from tuberculosis. For most of those three years, Feynman was working for the Manhattan Project at the atomic bomb laboratory in Los Alamos, and Arline was at a nursing home in Albuquerque, sixty miles away over rugged mountain roads. Feynman wrote to her in May 1945:

The doc came around special to tell me of a mold growth, streptomycin, which really seems to cure TB in guinea pigs—it has been tried on humans—fair results except it is very dangerous as it plugs up the kidneys…. He says he thinks they may soon lick that—and if it works it will become available rapidly….

Keep hanging on tho—as I say there is always a chance something will turn up. Nothing is certain. We lead a charmed life.

Streptomycin worked in humans and it became available rapidly, but not rapidly enough to save Arline. She died a month later.

Five of the letters are in a different category from the others. They were written to Feynman’s third wife, Gweneth, when he was traveling, leaving her at home. Gweneth was the mother of Carl and adoptive mother of Michelle. He obviously enjoyed writing to her. The letters are full of detailed observations of things that most travelers would miss. One of his gifts was the ability to walk into a place where he had never been before and see at a glance what was going on. It is his power of exact observation and vivid description that makes the letters memorable. The same gift made him a uniquely perceptive investigator of the Challenger shuttle disaster in 1986. When he was asked to serve on the commission investigating the causes of the disaster, he wanted to say no, but Gweneth said:

If you don’t do it, there will be twelve people, all in a group, going around from place to place together. But if you join the commission, there will be eleven people—all in a group, going around from place to place together—while the twelfth one runs around all over the place, checking all kinds of unusual things…. There isn’t anyone else who can do that like you can.5

He knew Gweneth was right, and so he said yes. His “Personal Observations on the Reliability of the Shuttle,” published as an appendix to the official report of the commission, is full of wisdom. After looking in detail at a number of ways that accidents can happen, he concludes that the expected rate of fatal shuttle accidents is about one per hundred flights. The second fatal accident, the Columbia disaster of February 1, 2003, showed that his estimate was close to the truth. But the politicians and administrators who run NASA have never admitted that he was right.

The five long letters to Gweneth were written from five different places: from Brussels when he was at a physics conference in 1961 and she was pregnant with Carl, from Warsaw when he was at another physics conference in 1962, from Athens when he was lecturing there in 1980, from Switzerland when he was visiting in 1982, and from Washington when he was serving on the shuttle commission in 1986. Each of them is a set piece, a framed story of a place and time, with vivid portraits of the people that he encountered. The Brussels story is staged in the royal palace, where he was introduced to the king and queen, with a hilarious description of the stiff and stupid formalities of royal conversation. Fortunately the queen’s secretary turned out to be a friendly ally, and Feynman was able to escape from the palace to spend a happy afternoon with the secretary and his wife and daughters in their country house.

The Warsaw story takes place in the dining room of the Grand Hotel, where Feynman is describing the frustrations of dealing with Communist bureaucracy. “Theoretically,” he wrote,

planning may be good etc—but nobody has ever figured out the cause of government stupidity—and until they do and find the cure all ideal plans will fall into quicksand.

The Athens story describes how the Greek educational system, with its overwhelming emphasis on the glories of classical Greece, gives children a bad start in life, teaching them that nothing they do can equal the achievements of their ancestors:

They were very upset when I said that the thing of greatest importance to mathematics in Europe was the discovery by Tartaglia that you can solve a cubic equation—which, altho it is very little used, must have been psychologically wonderful because it showed a modern man could do something no ancient Greek could do, and therefore helped in the renaissance which was the freeing of man from the intimidation of the ancients—what they are learning in school is to be intimidated into thinking they have fallen so far below their super ancestors.

The Swiss story is the longest and the most carefully composed, with a formal title, “The Curse of Riches.” It describes a visit that Feynman made to the country estate of a South American millionaire “who had inherited great wealth.” He built a grandiose house similar to William Randolph Hearst’s castle at San Simeon in California, with a large collection of Roman, Mayan, and Polynesian art treasures. Feynman concludes that his first favorable impressions

had turned into a vision of surrealistic horror—as I imagined the three—he, his wife and daughter…eating alone in that long room with unpainted walls, with the Roman paintings looking down on the dark scene lit only by candles…in an ancient candlestick…. Such, in this case, is the curse of wealth.

The Washington story was written when Feynman had barely survived his second major cancer operation, less than two years before his death. It describes his continuing duel with William Rogers, the chairman of the Challenger commission. Feynman was determined to investigate the facts of the case wherever they might lead, and Rogers was determined to keep him on a tight leash in case he might discover something that would be politically embarrassing. Feynman treated Rogers with studied politeness and did not openly rebel. He knew that he could beat Rogers in a battle of wits. He writes to Gweneth before the battle is won, anticipating victory. He explains how Rogers hopes to keep him snowed under with data and details

so they have time to soften up dangerous witnesses etc. But it won’t work because (1) I do technical information exchange and understanding much faster than they imagine, and (2) I already smell certain rats that I will not forget because I just love the smell of rats for it is the spoor of exciting adventure.

He later wrote Rogers in defense of the commission’s report:

We have laid out the facts and done it well. The large number of negative observations are a result of the appalling condition the NASA shuttle program has gotten into. It is unfortunate, but true, and we would do a disservice if we tried to be less than frank about it.

Why should we care about Feynman? What was so special about him? Why did he become a public icon, standing with Albert Einstein and Stephen Hawking as the Holy Trinity of twentieth-century physics? The public has demonstrated remarkably good taste in choosing its icons. All three of them are genuinely great scientists, with flashes of true genius as well as solid accomplishments to their credit. But to become an icon, it is not enough to be a great scientist. There are many other scientists, not so great as Einstein but greater than Hawking and Feynman, who did not become icons. Paul Dirac is a good example of a scientist greater than Feynman. Feynman always said, whenever the opportunity arose, that the “space-time approach” that led him to his new way of doing particle physics was directly borrowed from a paper of Dirac’s.6 That was true. Dirac had the original idea and Feynman made it into a useful practical tool. Dirac was the greater genius. But Dirac did not become an icon because he had no wish to be an icon and no talent for entertaining the public.

Scientists who become icons must not only be geniuses but also performers, playing to the crowd and enjoying public acclaim. Einstein and Feynman both grumbled about the newspaper and radio reporters who invaded their privacy, but both gave the reporters what the public wanted, sharp and witty remarks that would make good headlines. Hawking in his unique way also enjoys the public adulation that his triumph over physical obstacles has earned for him. I will never forget the joyful morning in Tokyo when Hawking went on a tour of the streets in his wheelchair and the Japanese crowds streamed after him, stretching out their hands to touch his chair. Einstein, Hawking, and Feynman shared an ability to break through the barriers that separated them from ordinary people. The public responded to them because they were regular guys, jokers as well as geniuses.

The third quality that is needed for a scientist to become a public icon is wisdom. Besides being a famous joker and a famous genius, Feynman was also a wise human being whose answers to serious questions made sense. To me and to hundreds of other students who came to him for advice, he spoke truth. Like Einstein and Hawking, he had come through times of great suffering, nursing Arline through her illness and watching her die, and emerged stronger. Behind his enormous zest and enjoyment of life was an awareness of tragedy, a knowledge that our time on earth is short and precarious. The public made him into an icon because he was not only a great scientist and a great clown but also a great human being and a guide in time of trouble. Other Feynman books have portrayed him as a scientific wizard and as a storyteller. This collection of letters shows us for the first time the son caring for his father and mother, the father caring for his wife and children, the teacher caring for his students, the writer replying to people throughout the world who wrote to him about their problems and received his full and undivided attention.

This Issue

October 20, 2005