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I. Rise of the Nuclear Age | Timeline

Invisible: Atomic Bomb Efforts in the US, USSR and National Socialist Germany

Simultaneously, physicists and their governments recognized that their discoveries had military potential. If any nation could harness the energy of nuclear fission in an explosion, a super bomb would possible. Within a few years of each other, and with varying degrees of commitment, resources and certainty, the United States, the Soviet Union and National Socialist Germany embarked on top secret nuclear weapons programs and the search for the so-called atomic bomb. By 1939, with World War II having broken out in Europe, publication on nuclear topics disappeared from scientific journals, and the race to build a nuclear bomb was on. The United States would win that race in 1945, and drop two bombs on Japan, Germany would falter, but the USSR followed just four years later with its first nuclear bomb.

In the US, Leo Szilard drafted a letter to President Franklin Roosevelt which he persuaded Albert Einstein to sign as his own. The letter raised the specter of a Nazi bomb and convinced Roosevelt to authorize a crash project to build a nuclear bomb, the Manhattan Project. Four years later, in July 1945 at Alamogordo, New Mexico, the US successfully detonated a nuclear bomb. The project commenced in earnest in 1942 under General Leslie Groves, a leading career soldier in the Army Corps of Engineers, the elite army specialists responsible for large scale construction projects. General Groves chose theoretical physicist J. Robert Oppenheimer to lead a secret project to design and test a nuclear bomb that was given the name ’Manhattan District’ project to confuse potential spies. After all, what super weapon project might occur in Manhattan? Oppenheimer was an interesting choice as a theoretician and somewhat without extensive administrative responsibility. But the force of his personality made him an excellent choice. Oppenheimer was unknown to the public; even most congress people and senators had no idea about the atomic bomb project.

Oppenheimer selected a site at Los Alamos, New Mexico, for the base of the project. Here physicists designed and built the bomb. At several other sites around the nation hundreds of other specialists and workers focused on other problems: at Oak Ridge, Tennessee, uranium separation; at Hanford, Washington, plutonium production; at the ’metallurgical laboratory’ at the University of Chicago, reactor design and neutron physics; and so on. Groves compartmentalized the research so that few individuals knew about the entire extent of the project. Compartmentalization also kept physicists from discussing moral and political aspects of nuclear weaponry. In this way, even the invisible atom was only partially seen by participants in the project.

The first nuclear test, called Trinity, was held at the Alamogordo Test Range, New Mexico, and involved an implosion weapon design that Los Alamos scientists referred to as the Gadget. In preparation for the explosion the scientists spent weeks developing the test grounds and observation bunkers, and designing the tower where they set the Gadget and equipment to measure whether their predictions of the size, temperature, speed and other factors related to the explosion held true. In May 1945 they first tested 108 tons of TNT laced with radioactive isotopes. The explosion helped them to set instruments to measure the Gadget test and indicate how fission products might spread. On the night of July 15, 1945, the scientists set the plutonium implosion weapon at Ground Zero. At 5:29:45 in the morning Trinity was held with a yield of 20 to 22 kilotons of explosive, confirming the scientists’ expectations.

Late in 1941, after repeated attempts, a Soviet physicist serving in the Red Army, Georgii Flerov, gained the attention of Stalin about the feasibility of nuclear weapons. Stalin ultimately ordered a crash program to develop an atomic bomb under the leadership of Secret Police Chief Lavrenty Beria. Stalin entrusted Igor Kurchatov with the scientific direction of the Soviet bomb project at Laboratory No. 2. Kurchatov was, in spite of his relatively young age and limited experience as research director, by all accounts an able administrator, perceptive critic and capable specialist. He had to navigate treacherous shoals between Beria and Stalin and supervise the activities of hundreds of scientists and thousands of workers including prison laborers who built the reactors, the uranium separation facilities, the plutonium production reactors and so on.

Kurchatov established so-called Laboratory Number 2 (today the Kurchatov Institure for Atomic Energy) to carry out the project. Dozens of other institutes were created in pursuit of the bomb, and hundreds of scientists and thousands, ultimately tens of thousands of Gulag prisoners were enlisted to build the mines, reactors, uranium separation and enrichment facilities needed for it. One of those facilities was Laboratory Number 1, the Ukrainian Physical Technical Institute in Kharkiv. Another was Arzamas in the Ural Mountains in Sarov where atomic and hydrogen bombs were designed. By the end of the Cold War, the Soviet nuclear establishment, both peaceful and military, was the largest in the world, with dozens of closed cities -- in or near Krasnoiarsk, Tomsk, Cheliabinsk, Sverdlovsk and elsewhere -- with over 1 million employees devoted entirely to weapons manufacture. Until his premature death in 1960, Kurchatov pursued peaceful applications and sought arms control measures, in his last years with Andrei Sakharov, the father of the Soviet hydrogen bomb and later dissident, Nobel peace prize laureate, and parliamentary deputy in the Gorbachev era.

The Soviet atomic bomb project took the same time as the US project (roughly four years), with almost exactly the same time elapsing from the start of the first Soviet reactor, the F-1, until the detonation of a nuclear weapon in August 1949, as in the US from reactor to bomb. Did espionage help the Soviets build a bomb? Klaus Fuchs, a physicist of German origin who worked on the Manhattan project was a spy for the Soviet Union. He passed along important information on the project including questions of uranium production and bomb design. This assisted Soviet physicists in designing their bomb, but more importantly confirmed for Beria and Stalin that their scientists were on the right path. After all, Soviet nuclear physics programs dated to the early 1930s. It also helped that Soviet specialists knew a bomb could be built -- the Americans had detonated three of them and published the so-called Smythe report on the military uses of nuclear energy that was translated into Russian weeks after its appearance in the US.

On August 7, 1945, seeking to end the Pacific War quickly, Harry S. Truman, who had assumed the presidency after Roosevelt’s sudden death, ordered a US bomber to drop a uranium atomic bomb on Hiroshima, killing 90,000 people. One week later, since Japan had not yet surrendered, the US annihilated Nagasaki with a plutonium bomb, killing another 70,000 people. The US is the only nation to have used nuclear weapons of mass destruction. Four years later, in Semipalatinsk, Kazakhstan, on August 29, 1949, the Soviets detonated their first atomic bomb, dubbed ’Joe 1’ by the Americans. It was a copy of the American Fat Man bomb plutonium implosion bomb that was dropped on Nagasaki.

Visible: The International Scientific Community

In the 1920s and 1930s, an international community of scholars turned attention to the structure of the atom: protons in the nucleus, electrons in a cloud circulating around the nucleus. Scientists from the USSR joined those in Germany and England, Denmark and France, Poland, the Czech Republic and Hungary, Canada and the United States to penetrate deeply into the atom. They met to share results at conferences covered widely in the media, for example, the Solvay Conferences on achievements in physics. They took fellowships to work abroad and visited their counterparts in Kharkiv, Ukraine, Cambridge, England, Santa Monica and Berkeley, California, Heidelberg, Munich and Berlin, Germany, and Copenhagen, Denmark. Their efforts resulted in the discovery of the neutron in 1932 which triggered the nuclear age. Nuclear physics consumed their attention for the next six or seven year in open competition to understand further the nature of radioactivity, atomic stability and structure, and they ultimately discovered Nuclear fission, the phenomenon from which all peaceful applications derive.

The physicists Henri Bequerel, Willhelm Roentgen, Ernest Rutherford of Cambridge, England, Niels Bohr of Copenhagen, Denmark, Pierre and Marie Curie , and J.J. Thompson contributed to the rise of nuclear physics through a series of discoveries concerning radioactivity, atomic structure, and the behavior of Protons, Neutrons and Electrons that make up the Atom. They made this invisible world visible. A number of the pioneers in the study of radioactivity themselves became sick or died from the effects of the invisible action of radiation on their bodies. Over the years, specialists have regularly decreased the amount and time of exposure to the action of ionizing radiation that is considered ’safe’ to humans and other living things.

In 1932, the so-called the miraculous year (Annus Mirabilus), James Chadwick discovered the neutron by bombarding elements with alpha particles, Carl David Anderson discovered the positron, and John Cockcroft and Ernest Walton produced the first artificial disintegration of the atomic nucleus. These discoveries triggered international investigation of the nucleus. Enrico Fermi in Rome, Kirill Sinelnikov and Alexandr Leipunskii in Kharkiv, Frederic and Irene Joliot-Curie and Edwin McMillan contributed to this basic research. Fermi induced artificial radioactivity in the laboratory, leading to the formation of transuranic elements. In 1938 Otto Hahn and Lise Meitner (assisted by Fritz Strassman) discovered fission: they determined that when uranium split it formed two lighter elements and gave off neutrons.

Nuclear research was very expensive. Some observers argue that 20 th century physics is the physics of the very small (subatomic particles), the very fast (various processes and things traveling at the speed of light), and the very expensive. The machines used for nuclear research -- particle accelerators and detectors, and later reactors -- required substantial infusions of funding from governments and foundations. To gain funding, physicists promised medical applications, for example cancer treatment. This made sense since X-rays had given rise to entire new fields of medicine, and revealed the body’s internal workings as never before. But the physicists did not promise to build bombs or reactors to produce electricity until a later date. Until World War II sent nuclear research into secrecy, such scientists and their teams around the world competed openly to be the first to explain such new-found phenomena as isotopes and fission.

A number of physicists had read H. G. Wells and Jules Verne in which the authors set forth fantastic stories of the power of the atom. The physicists’ predictions about nuclear bombs and such appeared appeared on the eve of World War II and were connected with the discovery of the fission. At this point, the visible world of the atom became the focus of top secret investigations for military applications -- the pursuit of the atomic bomb. There were clear military implications of the discovery of fission, for if the energy could be harnessed in an explosion then a new super weapon would result. This was precisely what most researchers immediately understood, and several of them, such as Hungarian �migr� Leo Szilard, sought self-censorship of ongoing research, while others soon approached their governments to commence crash programs in pursuit of weapons.

Two broader trends played out against the development of nuclear physics. One concerned the rise of National Socialist Germany and an ideological opponent of the USSR, and the growing tensions between them and the rest of the world. The passing of race laws under the Nazis led to the emigration of dozens of leading physicists from Central Europe -- Leo Szilard, Edward Teller, Albert Einstein many of them current or future Nobel laureates whose presence in British, American and Canadian laboratories helped the US first design, test and use nuclear weapons in 1945. The other concerned an increasingly xenophobic leadership of the USSR under Joseph Stalin, who established autarky in both economic and cultural relations. Soviet scientists, who had been part of the international community, were now shut off from it. Their nuclear research continued on a world level, but without the complete knowledge of the rest of the world. Hence many specialists were shocked when the USSR tested a nuclear bomb in August 1949, only four years after the US. Shockingly also, Nazi Germany and the USSR signed a secret non-aggression pact, the Ribbentrop-Molotov agreement, in 1939.