What Was the Manhattan Project?
In 1942, with the outcome of World War II still uncertain, the U.S. government began building Oak Ridge, Tennessee, an entire city that was to serve as the venue for a vast effort to enrich uranium as fuel for a new, atomic bomb it was developing in complete secrecy.
Oct 18, 2016
Originally published on: May 11, 2015
BY Ben Phelan
The Allies were faced with an awful choice: Build the bomb to oppose a potentially atomic Nazi Germany. Or do nothing, and hope that no one ever discovered the secrets of atomic power.
With a few exceptions, the scientists who worked on building the atom bombs for the Manhattan Project were gravely conflicted about their work. Here was a weapon of such violence that it would have no conceivable use as an instrument of conventional warfare. Because of its inherent power, it would be suitable only for carrying out attacks so massive and indiscriminate as to be tantamount to genocide. Though horrifying in a weapons application, the new physics involved were also irresistible, so abstract and powerful as to seem like magic. Atomic physics were "superb physics," in the words of Nobel laureate, and Project member, Enrico Fermi. And unlike the majority of cutting-edge science programs, the Manhattan Project had a budget — a huge budget, in fact, large enough to support the construction of an entire city, secret from the outside world, its purpose concealed even from its citizens: Oak Ridge, Tennessee.
An unofficial service emblem of the Manhattan Project. (Image source: Wikimedia Commons)
At the ROADSHOW in Charleston, West Virginia, in August 2014, two bound volumes of the Oak Ridge Journal newspaper, with dates corresponding to the duration of the Manhattan Project, were appraised at between $2,500 and $3,500 by Books & Manuscripts expert John Schulman. "Oak Ridge Attacks Japan," announced the front page of the August 9, 1945, edition. "Press And Radio Stories Describe 'Fantastically Powerful' Weapon."
Mammoth Undertaking
If not for the great galvanizing evil of Nazi Germany, the atom bomb may never have been attempted; the challenges were that great. The physics that, according to theory, would power the atom bomb were so new that some key areas were totally unknown. So a part of the Manhattan Project consisted of purely theoretical research. That knowledge, once achieved, then had to be given form, the physics embodied in a machine, the bomb itself. It was certainly possible that no existing materials would prove capable of realizing the physics, so the engineering difficulties were expected to be as great as the theoretical ones. And then the fuel, the radioactive elements uranium and plutonium, were terribly rare; minute quantities had to be refined out of massive ore loads, for which purpose the city of Oak Ridge was conceived and built. Incredibly, all elements of the Project, from basic research to mining operations to construction, had to take place simultaneously, at over 30 sites, employing 130,000 people, in complete secrecy. If any bomb-related intelligence leaked to Nazi Germany, there would be no opposing Hitler's quest for world dominion.
Atomic physics, much of it described by Germans, encompassed a radical rethinking of the nature of matter and, indeed, of reality itself. So an atom bomb would be different in every respect from all the bombs that had come before, the mechanics of which were no different from that of the firecracker: A flammable substance was encased in a shell of some kind and then ignited. The combustion process that followed used the surrounding oxygen to shuffle around the molecules comprising the fuel. This shuffling was accompanied by a sudden release of energy — an explosion. But no matter how large the bomb, at the end of the process all the elements would be present in the same proportions as at the beginning. If you started with one pound each of carbon, nitrogen and oxygen packed in a ball, you ended up with one pound each of carbon, nitrogen and oxygen, though now scattered as ash and smoke.
A New Branch of Physics
A long-established law of the universe was that the elements — oxygen, carbon, nitrogen, etc. — were unchangeable. An atom of oxygen was an atom of oxygen until the end of time. There was no process capable of transforming it into an atom of something else. But in the first third of the 20th century, it had become clear that there were exceptions. Some elements could indeed transform into other elements, via a little-understood process called radioactivity, which released much larger amounts of energy than simple combustion. If this process could be understood and exploited, the resulting weapon would be immensely more powerful than a conventional weapon, operating not according to the laws of chemistry that described the relationship among atoms and molecules, but to an entirely new branch of physics — the physics that governed the inner dynamics of the atom itself.
The engineering challenges arose directly from the tremendous power waiting to be exploited in the subatomic realm. The mechanism that was to power the bomb was a chain reaction that consumed the fuel, but the explosive energy released in the first instants of the bomb's detonation would be more than enough to disperse the rest of the fuel before the reaction could run its course. (In a conventional bomb, this is not generally a problem; the violence of the reaction is not so great that it quenches the explosion before it can run to completion.) A commonsense solution might be to tightly compress the bomb's fuel into a volume so small that it would be consumed before the explosion had the time to scatter it. But that proved to be devilishly tricky. Weaponized uranium and plutonium aren't ignited by something like a fuse; they don't sit quietly waiting for a spark. All it takes to initiate the chain reaction is to cram a bunch of it together. For that reason, an atom bomb could not come pre-assembled, with the fuel contained in a single chamber. The fuel had to remain diffuse, with not too much of it in one place, until the moment of detonation, at which point it would be somehow brought together so the reaction could begin. This coming together had to happen very fast — fast enough to prevent the explosion from quenching. Project scientists pursued two bomb designs: a gun-like mechanism that fired a bullet of uranium at a uranium target ("Little Boy"), and a more sophisticated design in which conventional explosives caused a sphere of plutonium to implode ("Fat Man").
Short-Lived Secret
Then there was the matter of sourcing the fuel itself. It's sometimes said that once you have enough uranium and plutonium, you're halfway to building an atom bomb. In a sense, this is an understatement: The uranium-enrichment operation at Oak Ridge consumed 63 percent of the Manhattan Project's budget, and employed three-fourths of its workers. The reason was that uranium was not only a rare element, but most of it, in excess of 99 percent, was useless in an atom bomb and had to be refined away. The Manhattan Project overcame these daunting numbers with brute force. Starting in 1942, it built an entire secret city, walled off from the rest of the world, whose sole purpose was processing uranium. At its peak, approximately 100,000 men and women worked in Oak Ridge's various facilities. None of them knew what it was they were doing. According to a 1945 article in Life magazine, "perhaps only a thousand ... were aware that work on atoms was involved," and "no more than a few dozen in the entire country knew the full meaning of the Manhattan Project."
On August 6, 1945, President Truman let the world in on the secret. “A short time ago,” he announced in a prepared statement, “an American airplane dropped one bomb” — one — “on Hiroshima and destroyed its usefulness to the enemy.” Three days later, he ordered a second atomic attack on Nagasaki. These two bombs each exploded with the energy of between 15,000 and 20,000 tons of TNT.
"Workers Thrill as Atomic Bomb Secret Breaks," read the front page of the Oak Ridge Journal. "Teamwork Responsible."
Three days after that, Japan surrendered. All the newspaper's readers could rightly take some of the credit. Through their toil, they had built a weapon so fearsome that an empire that had convincingly sworn to fight until the last Japanese citizen was slain capitulated completely, accepting humiliating terms of surrender. Only a maniac would take pleasure in the carnage itself. But the leaders of the Manhattan Project had faced a dilemma: The new science of nuclear physics seemed to indicate that an atom bomb was a physical possibility.
Nazi Germany was one of the most scientifically sophisticated nations the world had ever seen, and its plan of war called for the domination or destruction of every nation on Earth. Hitler's atom bomb program was staffed by geniuses who seemed, to contemporary observers, to stand a good chance of succeeding. So the Allies were faced with an awful choice. They could build the bomb to oppose a potentially atomic Nazi Germany. Or they could do nothing, and hope that no one, neither themselves nor Hitler, ever discovered the secrets of atomic power. That was a risk too frightening to take.
