The Manhattan Project | Chain Reaction | 1
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Imagine it's October 11th, 1939. You're a respected economist and banker paying a special visit to Washington, D.C. A young man in a dark suit escorts you down the marble hallways of the White House, and as you pass paintings of former U.S. presidents lining the wall, you grip the handle of your briefcase. Your escort stops and gestures to a door. Right this way, sir.

The man opens the door, and you step inside the Oval Office. Seated behind the resolute desk is President Franklin Delano Roosevelt. You take a seat on the sofa as he finishes a phone call. You were one of Roosevelt's key economic advisors on the creation of the New Deal. But today, you're not here to talk about financial policy. The president hangs up the phone and motions for you to take a seat across from him at the desk.

Thank you for taking the time to meet with me, Mr. President. Well, I would have liked it to happen sooner. Unfortunately, Mr. Hitler has caused a bit of a distraction in Poland. You might have heard about that. Indeed, I did. Just six weeks ago, Germany invaded Poland. And days later, the United Kingdom and France declared war on Germany. Now a Second World War is in full swing. Many are keen to keep the United States out of it.

You lean forward in your chair. Well, actually, Mr. President, the situation in Germany is exactly what I hope to discuss with you. All right, go on. You open your briefcase and retrieve an envelope, which you hand to the President. I'm here to deliver this letter on behalf of Albert Einstein. Really? Einstein? What's this about? Well, Dr. Einstein is very concerned. Last year, German scientists had a major breakthrough—

"'One that could deliver a powerful new form of energy to the world. "'And what's the cause for concern?' "'Well, sir, this energy could be put in service of a new kind of weapon. "'A bomb. One capable of unprecedented power. "'One that could destroy an entire city. "'And Dr. Einstein believes this is possible.' "'He does, Mr. President, as do many other scientists. "'And what do you think?' "'Well, sir, if the greatest minds on our planet foresee a danger, "'then I think we should listen very carefully.'

Roosevelt unfolds the letter and begins to peruse it. As it stands right now, Mr. President, the nation with the greatest chance of creating such a weapon is Germany. Dr. Einstein believes the United States should launch its own research effort to determine whether such a weapon is even feasible. And if it is, he believes we should build one before Hitler does.

Roosevelt looks you in the eye. Are we absolutely certain that the Germans are working to develop such a weapon? Well, this bomb would be fueled by a metallic ore called uranium. It's worth noting that since Germany took charge of Czechoslovakia, they've stopped the sale of all uranium from their mines. So they're keeping the uranium for themselves. Dr. Einstein believes that is a distinct possibility.

President Roosevelt's eyes narrow as he clenches the letter tight. He slaps his hand on the desk. This demands action. As the president picks up the phone and starts calling his military advisors, you breathe a sigh of relief. With Roosevelt's support, the United States government will now marshal its resources to harness the power of this new science. Still, one thought makes your blood run cold. If Hitler gets to the bomb first, the consequences are unimaginable.

From Wondery, I'm Lindsey Graham, and this is American History Tellers. Our history, your story. American History Tellers

On our show, we'll take you to the events, the times, and the people that shaped America and Americans, our values, our struggles, and our dreams. We'll put you in the shoes of everyday citizens as history was being made, and we'll show you how the events of the times affected them, their families, and affects you now. In October of 1939, President Franklin Delano Roosevelt met in the Oval Office with an economist named Alexander Sachs.

Sachs shared a letter from the most famous scientist on Earth, Albert Einstein, who warned that a race to build the first atomic weapon was underway. If the United States failed to act, Einstein said, Adolf Hitler could soon have a bomb of unimaginable power at his disposal.

Only a few hours after this meeting, Roosevelt ordered the formation of an advisory committee to study uranium and whether it could be used to power a bomb. Then, as World War II escalated and more nations fell to Germany, this committee reached a conclusion that led to the formation of a top-secret military effort.

Often called the Manhattan Project, it brought together thousands of experts from science and industry to attempt to harness the power of nuclear fission. The project's leaders faced enormous challenges. Not only was the science new and complex, but the unprecedented project required coordination on a massive scale, including the building of secret cities where tens of thousands of Americans would live and work. And the entire mobilization would have to be kept hidden from enemies and rivals.

The scientists of the project knew that if they were successful, they would be ushering in a new era, not just for the United States, but for all of humanity. But as the design of the first atomic bomb came closer to being realized, questions emerged among its creators of how and if such power should be used. This is Episode 1 in our three-part series, The Manhattan Project, Chain Reaction.

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Fuel up at Shell. Download the Shell app to find a station today. In early 1939, a 41-year-old physicist named Leo Szilard paid a visit to a hospital at Princeton University in New Jersey. Szilard was checking in on a friend, Eugene Wigner, a fellow physicist who was recovering from a case of jaundice. As the two men chatted, Wigner revealed startling news, a revelation that Szilard knew promised to transform their scientific field forever.

For many years, scientists had understood that every element in the universe was composed of incredibly tiny particles called atoms. They knew that within atoms were even smaller particles and a core called the nucleus, which was so minuscule it was assumed it would be impossible to divide into something smaller.

But Wigner told Szilard that a team of German scientists had done just that by bombarding uranium atoms with neutrons. The scientists called this process of splitting atoms nuclear fission.

When Szilard heard the news, he immediately grew concerned. In his view, the German scientists had unleashed the possibility of a devastating new power upon the world, because Szilard knew that while a single atom could only release a tiny amount of energy, barely enough to be noticed, a much greater power was possible. If an atom were to be split, it would release additional neutrons, which could cause other atoms to be split.

And those atoms would then release neutrons of their own, causing even more atoms to split and even more energy to be released. Szilard called this phenomenon a nuclear chain reaction. It was a process he had long envisioned might be possible, and now, if what his friend told him was true, German scientists had proved it was within their grasp.

Szilard knew that if scientists could control the chain reaction and make sure it moved at a slow rate, the energy could be kept safe and used to power cities and factories across the world. But scientists could also speed up that chain reaction. And with thousands of billions of atoms packed into a single ounce of uranium, Szilard believed a devastating amount of energy could be released in just a fraction of a second. A new kind of weapon would be born.

But something else troubled Szilard. He was born in Hungary but had lived and worked in Germany until 1933, when Adolf Hitler became chancellor. Szilard was Jewish, and he had seen firsthand the anti-Semitism and aggression in Nazi ideology. Like many other Jewish scientists, Szilard had fled Europe as the Nazis rose to power, understanding his family would not be safe inside Hitler's empire.

and Hitler clearly had ambitions to expand that empire. If German scientists were able to channel their understanding of nuclear fission into the development of an atomic bomb, Szilard knew that Hitler wouldn't hesitate to use it. Months after Szilard's meeting with Eugene Wigner at Princeton, the two physicists shared their concerns with another scientist Szilard had collaborated with in the past, Albert Einstein.

By 1939, the 60-year-old Einstein was the most famous scientist in the world. His theory of relativity, published decades earlier, had transformed the world's understanding of space, time, and gravity. His famous equation, E equals mc squared, captured the relationship between energy and mass, which was foundational to nuclear physics. And when Szilard shared his concerns about Germany developing an atomic weapon, Einstein immediately grasped the danger.

Like Szilard, Einstein was Jewish and had immigrated to the United States earlier in the decade to escape the Nazis. And although Einstein was a well-known pacifist, he agreed that the American government needed to understand the grave danger that would emerge if Hitler was the first to develop an atomic bomb. So Einstein collaborated with Szilard on a letter to President Franklin Roosevelt.

Szilard knew that if he had any hope to stop the Nazis, he had to get the president's attention. And if anyone could help him do that, it would be Albert Einstein.

On October 11, 1939, economic advisor Alexander Sachs delivered Einstein's letter to President Roosevelt during a visit to the White House. Sachs emphasized that government funding was urgently needed if the U.S. was to catch up with Germany in their understanding of atomic fission. And although Congress and the American people were desperate to keep the U.S. out of the war that had erupted in Europe, Einstein's letter convinced Roosevelt that something needed to be done.

The president ordered the formation of an advisory committee on uranium, which held its first meeting on October 21, 1939, just ten days after Roosevelt received Einstein's letter. The committee's goal was to deepen understanding of nuclear fission and to determine whether it was feasible to use its power as a weapon. If the answer was yes, the president would then decide whether to order the design and production of such a bomb.

The committee included military and civilian members and worked in secret. The group also solicited input from some of the country's top scientists, including Szilard. As Szilard and the other scientists launched their research, key challenges quickly became apparent.

First, the scientists discovered that not all uranium atoms could be split. Only a special variant, or isotope, known as U-235, could undergo fission in a way that could be used in a bomb. But U-235 had to be separated from other, more common forms of uranium, and accomplishing this would be difficult and time-consuming.

But by the end of 1940, however, scientists at the University of California in Berkeley discovered another metallic element that could possibly be used as fuel in an atomic weapon. It was a byproduct of their experiments with uranium, which they called plutonium, and they suspected it would be easier to produce than U-235. Time was of the essence, so the scientists decided the best course was to continue their research on both uranium and plutonium.

But another critical problem remained. In order to generate an atomic explosion, scientists needed to figure out how to trigger a controlled chain reaction. To accomplish this task, Szilard began to collaborate with an Italian physicist named Enrico Fermi.

Fermi was a professor at Columbia University in New York City and had recently earned the Nobel Prize for Physics. He was also a pioneer in nuclear physics. Szilard hoped that working together, he and Fermi could create the world's first nuclear reactor, a device capable of generating a self-sustaining atomic chain reaction. But as the months passed, Szilard and his colleagues became frustrated with the slow pace of government bureaucracy.

The scientists felt that they were pursuing a mission critical to the safety of the United States, but military leaders on the committee were highly skeptical of the project. One of Szilard's colleagues described the process as so slow it was like swimming in syrup. Meanwhile, fighting raged across the Atlantic, and officials and scientists in the United Kingdom were also growing increasingly concerned about Germany's potential to develop atomic weapons.

British scientists had first assumed it would take several tons of raw uranium to arm an atomic bomb, making the device too cumbersome to be useful. But in March 1940, scientists from British universities distributed a report that told a different story. According to their calculations, rather than tons of raw uranium, a devastating explosion could be generated by a very small quantity of U-235, perhaps as little as a single pound.

It was now clear that an atomic weapon could be viable, and it was likely that Germany was already winning the race to build one. In response to this report, the British Prime Minister Winston Churchill formed his own committee to investigate the possibility of building a bomb.

Both the American and British committees knew of each other and shared information as they advanced their understanding of the science. But by 1941, Churchill's committee was growing increasingly frustrated with the slow response from their American counterparts. To figure out what was causing the problem, one of Churchill's scientific advisors flew across the Atlantic to see for himself.

Imagine it's August 1941. You're an Australian physicist serving on Winston Churchill's Atomic Research Committee. But today, you're sitting in an office in Washington, D.C. Across the table from you is the head of the United States Advisory Committee on Uranium. He's a bureaucrat with a background in physics named Lyman Briggs. You're exhausted from the long journey you took to get here and are hoping to learn why you haven't been hearing much from your American counterparts. So, how was your flight from jolly old England? Quite

Quite cold, actually. They had to put me on a Royal Air Force bomber, and unfortunately there was no heat in the cabin. Oh, I'm sorry to hear that. But I'm not the only one who's grown cold.

Dr. Briggs, several months ago, we sent a report that summarized the progress the British team has made in its research. Yeah, I remember. And I think you know we were initially skeptical that such a weapon could be created, but we've reached an unexpected conclusion. Not only do we believe that such a bomb is possible, we think we could have one ready to deploy perhaps as early as 1943. It's all very encouraging. Yes, we very much agree, which is why we were surprised we never heard back from any of the scientists on your team.

We expected they would have questions for us. Mr. Briggs furrows his brow. Oh, well, you see, I never shared it with them. You try your best to hide your shock. You didn't. And why was that? I think we both understand that this is a highly classified material. Wide distribution of such a sensitive document would be a serious security risk. So as soon as I got your report, I locked it up in my safe.

You take a deep breath and try to remain calm. Dr. Briggs, I realize that the United States is not at war, but England is. We are under attack. Our soldiers and our civilians are dying every day.

There is no way we can push this work forward alone. Without the expertise and resources of the United States, we are sure to lose this race. I assure you that the United States is fully committed to supporting this effort, just as we are committed to supporting our allies. But we will not do so at the risk of allowing vital information to fall into the wrong hands.

You nod and do your best to hide your frustration. I understand that much of the American research has been focused on utilizing atomic fission as a source of energy. Would it be possible for those efforts to be refocused on weapons development? There's certainly room for discussion, but understand that the United States has interests in the science that expand beyond a mere weapon, and we will invest in those interests accordingly.

You know you won't get what you need from this meeting. You can't help but feel that Briggs is completely out of his depth. You feel alarmed and frustrated. You've been behind in the race to build an atomic bomb for 18 months. You're afraid it might as well be years.

In August 1941, a physicist named Mark Oliphant visited Washington, D.C. to meet with Lyman Briggs, the head of the U.S. Advisory Committee on Uranium. When Oliphant learned that Briggs had kept an important British report hidden in a safe, he lost all confidence that his concerns would be communicated properly to the American team of scientists. So Oliphant took matters into his own hands.

Ignoring Briggs' security concerns, Oliphant traveled the country and met directly with the American scientists who were contributing to the research on atomic fission. He made sure they understood the importance of the British Committee's findings and urged them to concentrate their research on weapons development.

One of the scientists who took heed of Oliphant's plea was Ernest Lawrence, a Nobel Prize-winning physicist at the University of California at Berkeley. Lawrence was leading critical work for the U.S. committee, focusing on developing a machine that could separate the U-235 isotope from raw uranium. Troubled by what he heard from Oliphant, Lawrence urged his scientific colleagues to take action. He also recruited new scientists to join the effort, people he felt could bring fresh thinking to solve problems.

Between the two of them, Oliphant and Lawrence were able to spark new momentum in the American effort. Communication between the American and British teams improved, and Roosevelt and Churchill began discussing ways to combine their separate research projects into a joint effort.

Then, on November 27, 1941, over two years after Einstein's letter was delivered to Roosevelt, the American team leading the atomic research effort sent a report to the White House. This document concurred with the findings of the British team. A bomb, fueled by atomic fission, was indeed feasible. But then, just ten days later, the stakes rose even higher.

On December 7, 1941, Japan launched a surprise air attack on the U.S. naval base at Pearl Harbor on the island of Oahu. Japanese bombs sank several American battleships, cruisers, and destroyers docked in the harbor, killing more than 2,000. Roosevelt called it an act of war. Three days later, Germany and Italy declared war on the U.S. America's posture in World War II had changed. Only weeks after Pearl Harbor, President Roosevelt ordered the launch of a new project.

For over two years, scientists from America and Great Britain had sought to determine whether an atomic bomb was possible. Roosevelt now decided it was time to turn those theories into practice. The United States would devote its vast resources to defeat the Axis powers and try to build the most powerful weapon the world had ever known.

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On January 19, 1942, President Franklin Roosevelt ordered a new phase of development for the atomic bomb project. No longer would the focus be solely on research and feasibility. The bomb would now move into production. Those who had been involved with the advisory committee knew it would be a daunting task. Not only would scientists need to design the bomb, they would need to build the facilities to produce uranium and plutonium.

In the summer of 1942, Roosevelt ordered the Army Corps of Engineers to take over the project. But both Roosevelt and the Army's top brass knew they needed a special leader to take the reins of such a massive undertaking. By September, their choice was made.

For two years, Colonel Leslie Groves had served as Deputy Chief of Construction for the Army Corps of Engineers. His role made him accountable for all Army construction projects inside the United States, including the Pentagon, which was still in the process of being built.

But when the 46-year-old Groves heard the news of his new assignment, he was disappointed. Like many Army officers, he yearned for an overseas assignment where he could lead combat troops and contribute directly to the war effort. Also, Groves had doubts about the project.

Over the previous months, he'd been advising the Army team that was setting up the organization that would support the effort. Groves believed the target dates for construction of the uranium enrichment plants seemed unrealistic based on how little was actually known about how they would work. And with the war in full swing, resources were hard to come by. Groves couldn't see how they'd be able to procure the physical materials required for building the extensive facilities that were needed.

But Groves' superiors told him that the president himself had approved his appointment, and if Groves did his job right, it could win the war. So regardless of his concerns, Groves accepted the new role, along with a promotion to brigadier general. The central office for Groves' new organization was located in New York City, across the street from City Hall. So on September 17, 1942, now General Leslie Groves took charge of the Manhattan Project.

Groves understood his directive. Provide the military with a weapon that would end the war and do it before the enemy could do the same. It was a race against time, so he got to work right away. Groves' first order of business was building the production plants that would create the material to fuel the bombs. There were still multiple theories around which technological approach would be successful, but one thing was certain. These production plants would need to be very, very big.

Groves estimated that the government would need to acquire 54,000 acres to house the buildings, nearly four times the size of the island of Manhattan. The sites would not only be home to industrial facilities, but would also need to offer housing and infrastructure for the tens of thousands of workers who would reside nearby. Essentially, an entire new city would need to be built.

The site also had to be centrally located, with good access to transportation and adequate water and power. But to avoid enemy surveillance, it also had to be secluded. And after just two days on the job, Groves made his choice. Imagine it's fall 1942. You're a farmer in eastern Tennessee, about 25 miles west of Knoxville. And after a long day in the fields, you're sitting in a well-worn easy chair in your living room, finally resting.

A warm fire crackles in the fireplace beside you, and you can hear your wife cooking in the kitchen. The smell of beef stew and dumplings fill in the air. As the sky outside grows dark, you feel content. But you're surprised to hear a knock on your door at this hour.

When you open it, you see a man wearing a dark suit and a stern expression. Excuse me, sir, are you the owner of this property? I am. Well, sir, I represent the United States District Court for the Eastern District of Tennessee. I'm here to give you notice that the government will be purchasing your land at the rate noted in this document. The man hands you a piece of paper. Purchase my land, but it's not for sale. I understand that. Nevertheless, you will have six weeks to vacate. A wave of total confusion hits you.

Your wife might be an earshot, so you decide to take the conversation outside. I'm sorry, sir, but I don't understand. How can the government do this? Under the Fifth Amendment of the Constitution, they can't. But why does the United States government want my farm? It's not just your property that's being purchased. Everyone in an 80-square-mile radius is getting the same notice.

You look east toward the Smoky Mountains and think of all the friends and neighbors whose homes will be taken from them. I don't think you understand, sir. My family moved here over a hundred years ago, and I've been working this land for fifty of them. I have to ask, why is the government taking it? Well, sir, the God's honest truth is I don't know. It has something to do with helping us win the war.

You glance at the paper in your hand. What's being offered to you is a small amount for such a large piece of land. And you love this corner of Tennessee. It's your home. It's painful to think of the possibility of leaving it behind. But then you remember your three sons. They're all serving in the armed forces, and two of them are overseas. Maybe your sacrifice could bring them home faster. You gaze out to the mountains one more time. You know what you need to do, even if it's going to break your heart to do it.

At the end of 1942, a government official visited the home of farmer William Gallagher in Roane County, Tennessee. He and his family had occupied his land for decades, but within weeks of the government official's visit, he and his wife vacated the farm. The price the government offered was paltry, and many of the 3,000 local residents forced to vacate endured extreme hardship and poverty.

General Groves regretted the sacrifice, but felt his only choice was to demand it. This rural area, 25 miles east of Knoxville, checked all the boxes for what he was looking for.

Not only was there plenty of space and adequate water and power, the site was nestled into a long valley with ridges that partitioned it into sections. This terrain would help to hide the facilities from prying eyes, and even better, if there was an explosion at one of the plants, the ridges would help protect the others from being damaged.

By this time in late 1942, there were two emerging theories for separating U-235 from raw uranium at the scale needed to make an atomic bomb. One was developed by Ernest Lawrence from the University of California at Berkeley and would utilize giant electromagnets. Another was developed by British scientists and would send uranium hexafluoride gas through a vast network of pipes where the smaller U-235 atoms would be sifted out in a process called gaseous diffusion.

And even though the theories were still being tested in labs, Groves ordered plants for both processes to move straight into full-scale production at the Tennessee site. He could not afford any delays waiting to find the best method. He chose both. And the site at which it would happen would be named Oak Ridge.

But right away, the electromagnetic plant at Oak Ridge faced a challenge. Lawrence estimated that in order to separate four ounces of U-235 a day, the facility required thousands of tons of magnets and a tremendous amount of copper wire to carry the electric current. But copper was in short supply since the military needed it to produce shell casings.

Members of Grove's team figured out a solution. Silver was a workable substitute for copper, and they knew just where they could get that silver, the United States Treasury. Within weeks, the Manhattan Project was able to borrow 14,000 tons of silver bullion from the Treasury with the promise that they would be returned following the war. The bars were promptly melted down and recast as conducting coils for the magnets.

But in addition to the refining of uranium-235, scientists were also exploring ideas for how plutonium could be produced at an industrial scale. The leading theory was that a controlled chain reaction in raw uranium would create plutonium in large quantities.

But it was still just a theory. Since 1940, Enrico Fermi and Leo Szilard had been attempting to create a controlled chain reaction. And as of November 1942, they had yet to achieve it. Still, Groves and his team began searching for a site where a plutonium plant could be located.

The race to produce fuel for the bomb was underway. But there was one more core problem for Groves to tackle, the design of the bomb itself. For this task, he needed to find a scientist who could inspire and mobilize the greatest minds in the country. And when U.S. intelligence officials learned of Groves' choice, they were shocked. In their view, the nation's most guarded secrets would be in the hands of a man who posed a national security risk. ♪

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In the fall of 1942, General Leslie Groves held a meeting at his office in Washington, D.C. Sitting across the table from him was a slim 38-year-old scientist with piercing blue eyes. His name was J. Robert Oppenheimer.

Over the previous weeks, Groves had focused on identifying a candidate to lead a critical aspect of the Manhattan Project, the design of the actual bomb. Oppenheimer was a well-respected theoretical physicist from the University of California at Berkeley who knew a lot about the subject. The year before, Ernest Lawrence had recruited Oppenheimer to contribute research for the Advisory Committee on Uranium.

Oppenheimer's assignment was to lead a team that could answer key questions related to how a bomb would function, how powerful such a weapon could be, how much uranium or plutonium it would require, and how a rapid chain reaction could be triggered inside the bombshell. Oppenheimer's team featured some of the country's most renowned theoretical physicists, and they respected his leadership.

And as their meeting in D.C. continued, Groves could see why Oppenheimer garnered that respect. Oppenheimer possessed a brilliant intellect and was able to expound on matters that expanded far beyond the realm of science. In fact, the only subject Groves thought Oppenheimer didn't know much about was sports. Oppenheimer also seemed to know how to turn talk into action. And Groves was impressed as Oppenheimer spelled out one of the core challenges of the atomic research effort.

The scientists were spread out in university laboratories across the country, and as a result, they weren't aware of each other's work and ended up duplicating efforts. Not only was labor being wasted, but time and money as well. Oppenheimer wanted to establish a central laboratory where all the scientists contributing to the effort would work and live.

As an engineer, Groves agreed, and soon Oppenheimer's intellect, eloquence, and leadership skills put him at the top of Groves' list. But as he consulted with other scientists and military colleagues, Groves discovered that there were many who questioned Oppenheimer's fitness for the job.

Oppenheimer was a theoretical physicist, which meant that he utilized mathematical models to explain natural phenomena. On this front, Oppenheimer had made brilliant breakthroughs. Back in 1939, Oppenheimer was able to utilize calculations to imagine what would happen to a star that had started to burn itself out. Even though such an event had never been witnessed, Oppenheimer determined that the star would be crushed into a dark entity with gravity so powerful that not even light would escape it.

His theory helped to predict an event that would happen decades later, the discovery of black holes in the universe. But the atomic bomb needed much more than just theory. It would require physical experimentation, and on this front, J. Robert Oppenheimer was decidedly lacking. But there was a final concern that weighed heavily on Groves' colleagues in the military. Oppenheimer had many friends and associates who were members of the Communist Party.

Ever since June 1941, when the Germans invaded the Soviet Union, the Soviets had been allies with the United States against the Axis forces. But the United States still didn't trust the Soviets. If Oppenheimer were to share information with his communist friends, U.S. security officials feared those secrets would be passed directly to the USSR.

But Groves didn't feel that the risks were serious enough to remove Oppenheimer from consideration. The general had a gut feeling that Oppenheimer was the best choice for the job. Not only did Groves admire his intellect, he could tell that Oppenheimer very much wanted the job, too. And Groves knew that ambition would serve the project well. So at the end of October 1942, Groves exercised his authority to choose J. Robert Oppenheimer to lead the effort to design an atomic bomb.

Immediately after this decision was made, Oppenheimer and Groves got to work investigating possible sites for a central laboratory. Like Oak Ridge, it needed to be isolated enough to evade enemy interference, but also centrally located and close to transportation hubs and key infrastructure. Oppenheimer had an idea for a location that might fit the bill.

For many years, his family had a ranch in the Sangre de Cristo Mountains near Santa Fe, New Mexico. Its natural beauty held a special place in Oppenheimer's heart, and he was confident the other scientists would be inspired by it. On top of that, it had an adequate supply of power, was close to transportation and railways, and was well hidden by the surrounding mountains.

So on November 16, 1942, Groves and Oppenheimer stepped onto the grounds of a private school for boys located 35 miles away from Oppenheimer's ranch. They quickly determined that the school could serve as an adequate base of operations for researchers while housing, laboratories, and additional facilities were being built around it. The school was located northwest of Santa Fe in the tiny rural town of Los Alamos.

It was soon decided that New Mexico would be the site of the new laboratory. But in another part of the country, a key breakthrough in the development of atomic energy was about to take place. Imagine it's a cold morning on December 2nd, 1942. You're a research scientist at the University of Chicago, and the laboratory you're working in today is somewhat unusual. You're standing on a squash court in a dark and cavernous space beneath the stands of the campus football stadium.

But you're not here to play a game. You're conducting an experiment that could change the world. Next to you is a giant pile of black bricks, nearly 20 feet high. Wires snake from the pile, connecting to machines and monitors that click and hum on a platform 15 feet above you. The leader of this experiment is studying those monitors carefully. He's an Italian physicist named Enrico Fermi, and you're waiting for his signal.

An assistant stands nearby, and he glances at you nervously. How much longer is he going to wait? Just be patient. He'll let us know when it's time. Your hand is gripping a horizontal metal rod buried at one end in a stack of graphite bricks. Over the last few hours, you've been pulling it out only inches at a time, under the direction of Dr. Fermi. There's just a little more to go before you remove the rod completely. Dozens of other scientists have gathered to see what will happen when you do that.

Sitting at the front row of the platform above you, you can see Dr. Leo Szilard leaning forward in anticipation. And then suddenly you see Dr. Fermi waving to you from above. You turn to your assistant. "Alright, here we go." Slowly but surely, you remove the rod. With every inch it's pulled further from the pile, you can hear the machines above you click and hum louder.

A pile of bricks before you is producing energy. And that energy is growing and growing. You can see Fermi give a thumbs up to the other scientists. You turn to your assistant. I think the pile's gone critical. How long is he going to keep it going? Well, if Dr. Fermi's calculations are correct, the energy it's generating is now self-sustaining. It should double in the next two minutes. And I imagine that's when he'll stop it. You don't think there's any danger in waiting that long? No, don't worry. That's what the bucket's for.

If the reaction spins out of control, we'll just douse it with cadmium. The assistant glances at a line of buckets next to the pile. Yeah, but if it does spin out of control, what do we really know is gonna happen? Should we be doing this in such a populated area? You try to ignore your assistant, but your hands start to sweat as you grip the rod. And finally, as the machinery around you reaches a crescendo, Fermi gives you a sign.

You slowly push the rod back into the pile of bricks, and the clicking immediately starts to slow down until it disappears completely. Finally, all is quiet, until you hear the sound of clapping. You and your assistant step back and join in, because you've just helped to prove that an atomic chain reaction is possible.

In December 1942, on a squash court in Chicago, physicist George Weil participated in an experiment that opened the door to the atomic age. Weil removed a cadmium rod from a pile of graphite bricks, the same substance used in pencil lead. Inside many of these bricks were holes filled with small amounts of uranium. The cadmium rod served as a kind of magnet for the neutrons that emanated from the uranium atoms.

But once Weil removed the final rod, the movement of those neutrons shifted. Soon enough, a nuclear reaction creating neutrons that collide into uranium and create more neutrons had begun. Weil and his colleagues had generated the first controlled atomic chain reaction. Enrico Fermi directed the experiment in Chicago. The Italian physicist had collaborated with Leo Szilard and dozens of other scientists to devise and build what became known as Chicago Pile 1.

the world's first nuclear reactor. The amount of energy created on the squash court that day was barely enough to power a light bulb, but scientists had proven a key principle. With the right concentration of fissionable material, scientists now knew that a massive amount of power could be released, and one day a chain reaction could power a city or a bomb.

Now it was up to J. Robert Oppenheimer to figure out how to build on Fermi's breakthrough. He had no idea how far the Germans had advanced in their own research, so he had to move quickly. Oppenheimer needed to direct a team of scientists to figure out how to trigger a fast-moving chain reaction inside a bombshell small enough to be carried by an airplane.

But success depended on convincing those scientists to first pack up their belongings and move to the rural wilderness of Los Alamos. And there, the greatest minds in the country would race to invent a powerful new weapon, one that could win the war and change the world. From Wondery, this is Episode 1 of The Manhattan Project from American History Tellers.

In our next episode, J. Robert Oppenheimer and his team rush to create the first atomic bomb at Los Alamos. But if they don't work fast enough, a weapon of unimaginable power could be placed in the hands of Adolf Hitler. Still, some scientists start to fear the dangers that could be unleashed if they succeed.

If you'd like to learn more about the Manhattan Project, we recommend American Prometheus by Kai Bird and Martin J. Sherwood, and Bomb! The Race to Build and Steal the World's Most Dangerous Weapon by Steve Shankin.

American History Tellers is hosted, edited, and produced by me, Lindsey Graham for Airship. Audio editing by Christian Paraga. Sound design by Molly Bach. Music by Lindsey Graham. This episode is written by Matt Almos, edited by Dorian Marina, produced by Alita Rozanski. Our production coordinator is Desi Blaylock, managing producer Matt Gant, senior managing producer Ryan Lohr, and senior producer Andy Herman. Executive producers are Jenny Lauer-Beckman and Marshall Louis for Wondery.

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