If you ever rented a video you probably wondered where the name came from. In World War II the Brits were bombing German cities, and they developed very large bombs that were capable of taking out a city block of buildings and houses. They were called blockbusters among other terms. Then things got worse.
Richard Rhodes told the story in his 1986 book The Making of the Atomic Bomb. The book tells of the development of modern nuclear physics and of the coming involvement of science in the world of politics and war. The book won the 1988 Pulitzer Prize for general non-fiction.
The German word thal (tal) means valley, and Sankt Joachimsthal in the Bohemia region of the Czech Republic was the site of a great mineral wealth. Silver came from the region and later uranium ore. The silver was struck into coins that became known as Joachimsthallers, and the thaller became the English dollar and the unit of currency for a new nation on the North American continent.
The uranium was the source from which Nobel chemists Marie and Pierre Curie extracted radium. Their discovery also revealed the enormous amount of energy released from nuclear reactions. Einstein had it right. His demonstration of the equivalence of matter and energy showed that a small quantity of matter represents millions of times the energy that can be extracted by chemical processes.
The ruling Magyar nobility of Hungary kept 33 percent of the population illiterate until the early twentieth century. They apparently overlooked the Jews, who comprised only 5 percent of the population, and the Jews profited from this slight by gaining professional ascendency when prosperity came to Hungary. This gain brought with it envy and persecution. As a result, a small collection of highly-developed Jewish minds fled Hungary and wound up mostly in the United States in time to help develop the atomic bomb.
Leo Szilard was one of these Jews, and his insight came as he was crossing a London street in 1933... By the time Szilard reached the opposite curb he had foreseen the end of humanity.
Leo Szilard was one of these Jews, and his insight came as he was crossing a London street in 1933. If the absorption of a neutron by an atomic nucleus caused that nucleus to fragment and also to release two more neutrons, then the cascading chain reaction could quickly result in the disintegration of a mass of the affected material with the instant release of a tremendous amount of energy. By the time Szilard reached the opposite curb he had foreseen the end of humanity.
European and particularly German persecution of Jews split the European science community. Nobel laureate physicists Werner Heisenberg, Erwin Schrödinger and Wolfgang Pauli stayed on, and some worked on an atomic bomb program for Germany during the war. German-born Jew Albert Einstein was hounded into leaving, eventually coming to the United States. The pacifist who established the basis for nuclear energy never worked on the atomic bomb project, but early on he lent his name to a letter that went to Franklin Roosevelt recommending its development.
Italian physicist Enrico Fermi won the Nobel Prize just in time to use the cash to extract himself and his Jewish wife from his Fascist homeland. In Chicago his team produced the first sustained nuclear chain reaction within a huge stack (pile) of uranium and highly-purified graphite blocks. This process was ultimately used to produce the new element plutonium for construction of atomic bombs.
Danish physicist and Nobel laureate Niels Bohr was the grand old man of atomic physics, having early in the century proposed the modern model of the atom. Denmark was invaded by the Nazis in 1940, and the Danes were fiercely resistant to the German occupation. Theirs was a quiet and stubborn resistance, one of strict non-collaboration. Bohr’s ancestry was partly Jewish, and he was a major champion of this resistance. The Nazis tolerated the resistance at first because they considered Danes to be almost German. However, when the Danes persisted in refusing to give up Jews for deportation, the Nazis clamped down, and Bohr fled the country, going at night in a small boat across the narrow strait between Denmark and Sweden. His trip from neutral Sweden to England was in the bomb bay of a Mosquito aircraft, wearing a parachute and carrying emergency flares. In case the Mosquito was shot down the plan was to drop the old man into the North Sea and hope for the best.
On a wintry day in Sweden Otto Frisch and his aunt, Lise Meitner, stopped on a snowy hiking trail and worked out the energy production from the fission of unstable nuclei. Marie Curie’s daughter Irene and her husband Frederic Joliot won the Nobel Prize for work in the transmutation of elements. As war approached they stopped publishing their work, but stayed in Europe and locked their papers in a secret vault.
In the United States Ernest Lawrence developed the cyclotron and used this device for separating the usable 235 isotope of uranium from the mostly 238 mass of the metal. American chemist Glenn Seaborg worked out the means to separate plutonium from uranium that had been bombarded by neutrons in Fermi’s pile. From 300 pounds of uranyl nitrate hexahydrate his team produced a microgram of plutonium.
The stage was set. We knew how to get the materials to make the bomb. All that was necessary was to scale up the process.
Army Corps of Engineers General Leslie Groves was a man of big projects. After completing the construction of the Pentagon Building he was tapped for the new Manhattan Project. With a blank check, almost unlimited power and little detailed planning he built in a few months the largest industrial concern in the world at the time. The Manhattan project encompassed wholly new research laboratories and huge industrial plants erected on newly-purchased land. An observer noted later that the United States essentially duplicated its entire automobile industry to build the bomb.
The motivation was two parts. It was known that Germany, the Soviet Union and Japan had the foundations for developing the bomb. To face these adversaries naked in a nuclear world would be unthinkable. The other motivation was expediency.
Since the days of the Great War there had been the dream of having weapons so powerful that an adversary would capitulate before economic and human costs became ruinous. The machine gun proved incapable of providing this benefit, even after the British saw around 19,000 killed in one day. Neither did poison gas provide such a benefit.
Here, also, saw the advent of the warrior-scientist, as German scientists contributed to the development of gas warfare. Otto Hahn was a Nobel Prize chemist, as was Fritz Haber. Together they developed gas agents for battle and even participated in battlefield logistics. Later Hahn fiercely opposed Hitler’s program of Jewish persecution and extermination, and he learned in horror of the Hiroshima bombing while in British captivity following the defeat of Germany in World War II.
The early twentieth century also witnessed a numbing of the senses toward civilian casualties. Modern weapons were less discriminating. Not only soldiers, but the infrastructure that supported the soldiers’ war became a target. A factory that built guns was bombed, along with the civilian workers inside. Later it became permissible in our minds to also bomb the workers’ homes so they would not be able to perform their factory jobs. Ultimately we saw fit to lay waste to large residential areas in futile attempts to force our adversaries to capitulate.
The Germans got the idea early on. Poland was the first to suffer, with Warsaw being pounded to rubble before it surrendered. The German bombing of Rotterdam convinced the Dutch to quickly give up the fight before other cities suffered the same fate. When England refused to make peace following their defeat at Dunkirk, the German air force sought to suppress the RAF in preparation for an invasion. When German bombers hit the city of London by mistake, the Brits replied in kind and bombed Berlin. The Germans then turned their attention to British cities, and thousands of civilians were killed while the RAF recovered its strength and proceeded to defeat the Germans in the air.
The British and the Americans went on to beat the Germans at their own game and gave that country ten times over its own measure. On a hot night allied bombers set great fires in Hamburg and followed up the next day. Thousands died within a few hours. Other cities followed with Dresden being the most notable with tens of thousands killed over two days of bombing.
On the Pacific side the war against civilians took an even uglier turn. The atrocities perpetrated by the Japanese army and the fanatical determination of Japanese to fight to the death convinced the Americans that threat of defeat would not force the Japanese to surrender. How much it took to harden the heart of General Curtis LeMay may not be known, but he took on the job of bombing the Japanese Empire into ashes. Raids on Japanese cities resulted in the deaths of 100,000 or more in Tokyo and other large cities. On the last day of the war, after Hiroshima and Nagasaki had been nearly obliterated, LeMay’s bombers continued their attacks on Osaka.
Hans Bethe, who determined the source of energy from the sun and won a Nobel Prize, was the instrumental designer of the bomb. Robert Oppenheimer, who grew up as a pampered Jewish intellectual, became the driving force behind the scientific effort. His surprising administrative skills and enormous scientific talent held the project together and ensured success beyond original expectations. Oppenheimer had vacationed in New Mexico as a sickly youth, and came to know the region around the mesa of Los Alamos. Groves purchased the site on the mesa of a boys school, and the best scientific minds of the early twentieth century came there to work.
In the beginning it was not certain the principle envisioned by Szilard in 1933 could be made to work in a bomb. Uranium 235 turned out to be the only isotope of the metal that had the properties to produce a chain reaction. A small sample would not sustain a chain reaction, because it would lose neutrons before they could induce additional fission. A large enough mass would go in a microsecond without additional help. Somewhere in between the self-produced neutron flux of the metal would multiply until the metal became hot enough to vaporize. The trick was to go from a sub-critical mass to a critical mass in a very short time, before the reaction had time to vaporize the remainder of the metal. There was also the problem of external neutrons. What was a subcritical mass at sea level could become critical at higher altitudes, where neutrons from cosmic rays were more abundant.
The solution for uranium was to shoot a plug of uranium at high velocity into a sub-critical mass, producing a super-critical mass. This method was so sure and so well worked out in advance that it was not even tested before use. The first atomic bomb used in warfare was a uranium bomb.
Plutonium was another matter. Plutonium 238 has a much shorter half-life than U235, and spontaneous neutrons abound. Assembling a critical mass would be more difficult for plutonium.
The solution for plutonium was to use high explosives to compress a sphere of the metal. The plutonium mass would be about the size of an orange, only with a hollow core. In the initial test on 16 July 1945 about two tons of high explosive, carefully molded and machined into the correct shape to produce a focused pressure wave, was detonated around this core.
The pressure wave collapsed the hollow plutonium sphere. Within the hollow of the sphere was a trigger of polonium, which gave off ample alpha particles, and also beryllium, which produced neutrons in abundance when bombarded with alpha particles. The pressure wave compressed the plutonium metal to twice its density, but could not hold it there. During one brief instant the neutron surge from the beryllium was necessary to ensure there were some neutrons to get the reaction going before the plutonium expanded back to its natural density.
The test was a complete success, producing a blinding flash of light and a fire ball that fused the sand of the New Mexico desert. Standing some distance away, Enrico Fermi measured the yield of the explosion by dropping bits of paper into the surge from the blast. He reckoned approximately 10,000 tons of TNT equivalence. About a gram of matter had been converted into energy.
Three weeks later a uranium bomb exploded over Hiroshima. The physical effects were the same, except a human element was involved. In the order of 100,000 people, mostly civilians, died as a direct result. The lucky ones were those vaporized by the flash. Others, farther away, had their skin instantly burned off by the intense heat.
The bomb released energy in the order of 10,000 to 20,000 tons of TNT, but the effects were not the same as a chemical explosion. The Hiroshima bomb produced temperatures and thermal radiation many times the intensity of a chemical explosion. Additionally, the ionizing radiation from the bomb produced the predicted result of a slow and painful death to many who would otherwise have survived.
At this point the Japanese government was still unsure how to respond. Devastation at Hiroshima was so complete that it took a day to comprehend what had happened. Three days after Hiroshima, a B-29 unleashed a plutonium bomb on Nagasaki. Finally the leaders of the Empire began to realize that in short order the Japanese race would disappear from the face of the Earth unless they could get the Americans to cease and desist. Surrender was still an ugly word among the Japanese leadership, and a minor revolt in the upper ranks attempted to forestall the inevitable. Still the Japanese rulers bargained for retention of the Emperor, and when the allies agreed, the military government conceded, and the bombing stopped—with LeMay’s last mission over Osaka.
One of the Jewish refugees from Hungary was Edward Teller. He was prominently involved in the atomic bomb project, and it quickly became apparent to him and to others that the temperatures and pressures of a fission bomb detonation would induce the fusion of hydrogen, especially heavy hydrogen. Since hydrogen 1 and hydrogen 2 are not radioactive, any amount of the material could be clustered next to the fission bomb trigger, and very large hydrogen bombs could be produced. The first hydrogen bomb was detonated at ground level and produced a crater half a mile deep.
The world has not been the same since. Nation states, a fairly recent concept, have come to recognize that nuclear weapons can be the tool of their imminent demise and have started to act accordingly. One result has been the lack of any wide-spread wars since 1945. Douglas McArthur wanted to use the atomic bomb in the Korean conflict, and President Truman nixed the idea. The prospect of a nuclear exchange between the United States and North Korea’s patron, the Soviet Union, was obviously on Truman’s mind.
Richard Rhodes tells the story with a clarity and with an attention to detail seldom matched. The book is extremely well researched with sources drawn from public records, private notes and declassified files. As much a tale of the construction of a horrible weapon, The Making of the Atomic Bomb is a history of science and a revelation of how serious science is done.
It’s about people who have already won a Nobel Prize getting dirty and carrying blocks of sooty graphite and packages of uranium compound into the lab. It’s (future Nobel winner) Luis Alvarez first learning of induced fission while reading the San Francisco Chronicle in a barber’s chair and rushing off to his lab, with an unfinished hair cut. It’s General Groves putting a tail on Robert Oppenheimer and learning that the married directory of the Manhattan Project science team spent the night with an ex-girlfriend, who was an avowed communist.
Rhodes brought the science and the sacrifice down to human terms. Reading this classic we can come to know of these scientists as people and to appreciate the personal sacrifices they wrestled with to pull off this tremendous accomplishment in a time of national urgency.
The book also emphasizes a critical lesson. Science shows us the world is how it is, not how we wish it to be. The scientists could not keep the principles of nuclear energy a secret from society, even had they wished to. The facts had always been there for them or for anybody who came after to reveal. The genie had not been trapped within a bottle, because the bottle never had a lid on it.