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by Michio Kaku

  Einstein, although in exile, was besieged with job offers from around the world. Leading universities in England, Spain, and France wished to capture this world-famous figure. Previously, he had been a guest professor at Princeton University. He had spent his winters in Princeton and his summers in Berlin. Abraham Flexner, representing a new institute to be formed at Princeton, largely with a five-million-dollar fund from the Bamberger fortune, had met several times with Einstein and approached him about the possibility of moving to the new institute. What appealed to Einstein was the fact that he would be free to travel and free of teaching duties. Although he was a popular lecturer, regularly breaking up audiences with his antics and enchanting royalty with amusing anecdotes, teaching and lecturing duties were taking time away from his beloved physics.

  One colleague warned Einstein that coming permanently to the United States was like “committing suicide.” The United States, before the sudden influx of Jewish scientists fleeing Nazi Germany, was considered a quiet backwater of science, with almost no institutions of higher learning capable of competing with Europe’s. Defending his choice, Einstein wrote to Queen Elizabeth of Belgium, “Princeton is a wonderful little spot…a quaint ceremonious village of puny demigods on stilts. By ignoring certain special conventions I have been able to create for myself an atmosphere conducive to study and free of distraction.” The news that Einstein had settled in the United States was heard around the world. The “pope of physics” had left Europe. The new Vatican would be the Institute for Advanced Study at Princeton.

  When Einstein was shown his office for the first time, he was asked what he needed. Besides a desk and a chair, he said he needed a “large wastebasket…so I can throw away all my mistakes.” (The institute also apparently made an offer to Erwin Schrödinger. But the latter, it is said, who was often accompanied by his wife and mistress and practiced an “open marriage” with a long list of lovers, found the atmosphere too stifling and conservative.) The American people were fascinated by the new arrival in New Jersey, who instantly became the country’s most famous scientist. Soon, he was a familiar figure to all. Two Europeans, on a bet, sent a letter to “Dr. Einstein, America,” to see if it would reach him. It did.

  The 1930s were hard on Einstein personally. It seemed as if his worst fears about his son Eduard (fondly nicknamed Tedel) were confirmed when Eduard finally suffered a nervous breakdown in 1930 after a failed romance with an older woman. He was taken to the Burghozli psychiatric hospital in Zurich, the same hospital where Mileva’s sister had been institutionalized. Diagnosed as schizophrenic, he was never to leave the care of an institution for the rest of his life except for short visits. Einstein, who always suspected that one of his sons might inherit mental problems from his wife, blamed “grave heredity.” “I have seen it coming, slowly but irresistibly, ever since Tedel’s youth,” he wrote sadly. In 1933, his close friend Paul Ehrenfest, who helped to stimulate the early development of general relativity but suffered from depression, eventually committed suicide, shooting and killing his young mentally retarded son in the process.

  After a prolonged, painful illness, Elsa, who had been with Einstein for about twenty years, died in 1936. According to friends, Einstein was “utterly ashen and shaken.” Her death “severed the strongest tie he had with a human being.” He took it hard but managed to slowly recuperate. He would write, “I have got used extremely well to life here. I live like a bear in my den…. The bearishness has been further enhanced by the death of my woman comrade, who was better with other people than I am.”

  After Elsa’s death, he would live with his sister Maja, who had fled the Nazis; his stepdaughter Margot; and his secretary, Helen Dukas. He had started the final phase of his life. During the 1930s and 1940s he aged rapidly, and without Elsa to constantly harp about his appearance, the dashing, charismatic figure who dazzled kings and queens in his tuxedo reverted back into the old, bohemian ways of his youth. He now became the white-haired figure remembered most dearly by the public, the sage of Princeton, who would good-humoredly greet both children and royalty alike.

  For Einstein, however, there was no rest. While at Princeton, he faced yet another challenge, the quest to build an atomic bomb. Back in 1905, Einstein had speculated that his theory might be able to explain how a small amount of radium could glow ferociously in the dark, its atoms releasing large quantities of power without apparent limit. In fact, the amount of energy locked in the nucleus could easily be a hundred million times greater than that stored in a chemical weapon. By 1920, Einstein had grasped the enormous practical implications of the energy locked in the nucleus of the atom when he wrote, “It might be possible, and it is not even improbable, that novel sources of energy of enormous effectiveness will be opened up, but this idea has no direct support from the facts known to us so far. It is very difficult to make prophecies, but it is within the realm of the possible.” In 1921, he even speculated that at some point far in the future, the current economy, based on coal, might eventually be replaced by nuclear energy. But he also clearly understood two enormous problems. First, this cosmic fire could be used to forge an atomic bomb, with horrible consequences for humanity. He wrote prophetically, “All bombardments since the invention of firearms put together would be harmless child’s play compared to its destructive effects.” He also wrote that an atomic bomb could be used to unleash nuclear terrorism and even a nuclear war: “Assuming that it were possible to effect that immense energy release, we should merely find ourselves in an age compared to which our coal-black present would seem golden.”

  Last, and most important, he realized the enormous challenge in producing such a weapon. In fact, he doubted that it was doable in his lifetime. The practical problems of taking the terrible power locked in a single atom and magnifying it trillions of times was beyond anything possible in the 1920s. He wrote that it was as difficult “as firing at birds in the dark, in a neighborhood that has few birds.”

  Einstein realized that the key might be to somehow multiply the power of a single atom. If one could take the energy of an atom and then trigger the subsequent release of energy from nearby atoms, then one might be able to magnify this nuclear energy. He hinted that a chain reaction might happen if “the rays released…are in turn able to produce the same effects.” But in the 1920s, he had no idea how such a chain reaction might be produced. Others, of course, also toyed with the idea of nuclear energy, not to benefit humanity, but for malevolent reasons. In April 1924, Paul Harteck and Wilhelm Groth informed the German Army Ordinance Department that “the country that exploits it first will have an incalculable advantage over the others.”

  The problem of releasing this energy is as follows: The nucleus of the atom is positively charged and hence repels other positive charges. Thus, the nucleus is protected against any random collisions that might unlock its nearly limitless energy. Ernest Rutherford, whose pioneering work led to the discovery of the nucleus of the atom, dismissed the atomic bomb, stating that “anyone who expects a source of power from the transformation of these atoms is talking moonshine.” This stalemate was broken dramatically in 1932 when James Chadwick discovered a new particle, the neutron, a partner of the proton in the nucleus that is neutral in charge. If one could fire a beam of neutrons at the nucleus, then the neutron, undeterred by the electric field around the nucleus, might be able to shatter it, releasing nuclear energy. The thought occurred to physicists: a beam of these neutrons might effortlessly split the atom and trigger an atomic bomb.

  While Einstein had doubts about the possibility of an atomic bomb, key events leading to nuclear fission were accelerating. In 1938, Otto Hahn and Fritz Strassmann of the Kaiser Wilhelm Institute for Physics in Berlin electrified the world of physics by splitting the uranium nucleus. They found traces of barium after bombarding uranium with neutrons, which indicated that the uranium nucleus split in half, creating barium in the process. Lise Meitner, a Jewish scientist and colleague of Hahn who had fled the Nazis, and her
nephew Otto Frisch provided the missing theoretical basis to Hahn’s result. Their results showed that the debris left over from the process weighed a bit less than the original uranium nucleus. It seemed as if mass was disappearing in this reaction. The splitting of the uranium atom also released 200 million electron volts of energy, which apparently appeared out of nowhere. Where did the missing mass go, and where did this energy mysteriously come from? Meitner realized that Einstein’s equation E = mc2 held the key to this puzzle. If one took the missing mass and multiplied it by c2, then one found 200 million electron volts, precisely according to Einstein’s theory. Bohr, when told of this startling verification of Einstein’s equation, immediately grasped the significance of this result. He slapped his forehead and exclaimed, “Oh, what fools we all have been!”

  In March of 1939, Einstein told the New York Times that the results so far “do not justify the assumption of a practical utilization of the atomic energies released in the process…. However, there is no single physicist with soul so poor who would allow this to affect his interest in this highly important subject.” Ironically, that very same month, Enrico Fermi and Frédéric Joliot-Curie (Marie Curie’s son-in-law) discovered that two neutrons can be released by the splitting of the uranium nucleus. This was a staggering result. If these two neutrons can go on to split two other uranium nuclei, then this would result in four neutrons, then eight, then sixteen, then thirty-two, ad infinitum, until the unimaginable power of the nuclear force was released in a chain reaction. Within a fraction of a second, the splitting of a single uranium atom could trigger the splitting of trillions upon trillions of other uranium atoms, releasing unimaginable quantities of nuclear energy. Fermi, looking out his window in Columbia University, mused grimly that a single atomic bomb could destroy all that he could see of New York City.

  The race was on. Alarmed at the rapid speed of events, Szilard was worried that the Germans, who were leaders in atomic physics, would be the first to build an atomic bomb. In 1939, Szilard and Eugene Wigner drove to Long Island to visit Einstein to sign a letter that would be given to President Roosevelt.

  The fateful letter, one of the most important in world history, began, “Some recent work by E. Fermi and L. Szilard, which has been communicated to me in manuscript, leads me to expect that the element uranium may be turned into a new and important source of energy in the immediate future.” Ominously, the letter noted that Hitler had invaded Czechoslovakia and had sealed off the Bohemian pitchblende mines, a rich source of uranium ore. And then the letter warned, “A single bomb of this type, carried by boat or exploded in a port, might well destroy the whole port with some of the surrounding territory. However, such bombs might very well prove to be too heavy for transportation by air.” Alexander Sachs, a Roosevelt advisor, was given the letter to pass onto the president. When Sachs asked Roosevelt if he understood the extreme gravity of the letter, Roosevelt replied, “Alex. What you are after is to see that the Nazis don’t blow us up.” He turned to General E. M. Watson and said, “This requires action.” Only six thousand dollars was approved for the whole year’s research on uranium. However, interest in the atomic bomb was given a sudden boost when the secret Frisch-Peierls report reached Washington in the fall of 1941. British scientists, working independently, confirmed all the details outlined by Einstein, and on December 6, 1941, the Manhattan Engineering Project was secretly set up.

  Under the direction of J. Robert Oppenheimer, who had worked on Einstein’s theory of black holes, hundreds of the world’s top scientists were secretly contacted and then shipped out to Los Alamos in the desert of New Mexico. At every major university, scientists like Hans Bethe, Enrico Fermi, Edward Teller, and Eugene Wigner quietly left after receiving a tap on the shoulder. (Not everyone was pleased by the intense interest in the atomic bomb. Lise Meitner, whose work helped to trigger the project, staunchly refused to be part of any work on the bomb. She was the only prominent Allied nuclear scientist to refuse the call to join the group at Los Alamos. “I will have nothing to do with a bomb!” she stated flatly. Years later, when Hollywood scriptwriters tried to glamorize her in the film The Beginning of the End, as the woman who bravely smuggled out the blueprint for the bomb as she fled Nazi Germany, she replied, “I would rather walk naked down Broadway” than be part of this fanciful, scurrilous effort.)

  Einstein was aware that all his close colleagues at Princeton were suddenly disappearing, leaving a mysterious mailing address in Santa Fe, New Mexico. Einstein himself, though, was never given the tap on the shoulder and sat out the entire war at Princeton. The reason for this has been revealed in declassified war documents. Vannevar Bush, the chief of the Office of Scientific Research and Development and Roosevelt’s trusted advisor, wrote, “I wish very much that I could place the whole thing before him [Einstein]…but this is utterly impossible in view of the attitude of people here in Washington who have studied his whole history.” FBI and army intelligence concluded that Einstein could not be trusted: “In view of his radical background, this office would not recommend the employment of Dr. Einstein, on matters of a secret nature, without a very careful investigation, as it seems unlikely that a man of his background could, in such a short time, become a loyal American citizen.” Apparently, the FBI did not realize that Einstein was already well aware of the project and in fact had helped to set it into motion in the first place.

  Einstein’s FBI file, recently declassified, runs 1,427 pages. J. Edgar Hoover had targeted Einstein as being either a Communist spy or a dupe at best. The agency carefully screened every piece of gossip about him and filed it away. Ironically, the FBI was curiously negligent in confronting Einstein himself, as if they feared him. Instead, agents preferred to interview and harass those surrounding him. As a result, the FBI became a repository of hundreds of letters from every crank and paranoid. In particular, they filed away reports that Einstein was working on some kind of death ray. In May 1943, a navy lieutenant called on Einstein, asking him if he would be willing to work on weapons and high explosives for the U.S. Navy. “He felt very bad about being neglected. He had not been approached by anyone to do any war work,” wrote the lieutenant. Einstein, always quick with a quip, remarked that he was now in the navy without having to get a haircut.

  The intense Allied effort to build an atomic bomb was stimulated by fears of the German bomb. In reality, the German war effort was badly understaffed and underfunded. Werner Heisenberg, German’s greatest quantum physicist, was put in charge of a team of scientists to work on the German project. In the fall of 1942, when German scientists realized that it would take another three years of strenuous effort to produce an atomic bomb, Albert Speer, the Nazi armaments minister, decided to temporarily shelve the project. Speer made a strategic error, assuming that Germany would win the war in three years, making the bomb unnecessary. Nevertheless, he continued funding research on nuclear-powered submarines.

  Heisenberg was hampered by other problems. Hitler declared that ordinance development would proceed only on weapons that promised results in six months, an impossible deadline. In addition to a lack of funding, German laboratories were under attack by Allied forces. In 1942, a commando squad successfully blew up Heisenberg’s heavy-water factory in Vemork, Norway. In contrast to Fermi’s decision to build a carbon-based reactor, the Germans chose to build a heavy-water reactor that could use natural uranium, which was plentiful, rather than the extremely rare uranium-235. In 1943, the Allies hit Berlin hard with saturation bombing, forcing Heisenberg to move his laboratory. The Kaiser Wilhelm Institute for Physics was evacuated to Hechingen, in the hills south of Stuttgart. Heisenberg had to build Germany’s reactor in a rock cellar in nearby Haigerloch. Under intense pressure and bombing, they never succeeded in sustaining a chain reaction.

  Meanwhile, physicists in the Manhattan Project were rushing to process enough plutonium and uranium for four atomic bombs. They were doing calculations right up to the time of the fateful detonation in Alamogordo, New Mexico
. The first bomb, based on plutonium-239, was detonated in July 1945. After the decisive Allied victory over the Nazis, many physicists thought that the bomb would be unnecessary against the remaining enemy, Japan. Some believed that a demonstration atomic bomb should be detonated on a deserted island, witnessed by a delegation of Japanese officials, to warn the Japanese that surrender was inevitable. Others even drafted a letter to President Harry Truman asking him not to drop the bomb on Japan. Unfortunately, this letter was never delivered. One scientist, Joseph Rotblatt, even resigned from the atomic bomb project, stating that his work was finished and that the bomb should never be used against Japan. (He would later win the Nobel Prize for peace.)

  Nevertheless, the decision was made to drop not one, but two atomic bombs on Japan in August 1945. Einstein was vacationing at Saranac Lake in New York. That week Helen Dukas heard the news on the radio. She recalled that the report “said a new kind of bomb has been dropped on Japan. And then I knew what it was because I knew about the Szilard thing in a vague way…. As Professor Einstein came down to tea, I told him, and he said, ‘Oh, Weh’ [Oh my God].”

  In 1946, Einstein made the cover of Time. Ominously, this time there was a nuclear fireball erupting behind him. The world suddenly realized that the next war, World War III, might be fought with atomic bombs. But, Einstein noted, because nuclear weapons might send civilization back thousands of years, World War IV would be fought with rocks. That year, Einstein became chairman of the Emergency Committee of Atomic Scientists, perhaps the first major anti-nuclear organization, and used it as a platform to argue against the continued building of nuclear weapons—and to advocate one of his cherished causes, world government.