But having miscalculated the amount of uranium it would take to set off an atomic bomb, the Germans figured that the United States would never be able to produce the quantity needed. The Americans, at first sure the Germans were nearing a workable weapon, slogged away, racing against a nightmarish hypothetical: Adolf Hitler’s nuclear bomb.
Many uranium cubes that are probably remnants of the long-since-failed Nazi nuclear program were brought to the United States after the war. Surprisingly to some researchers, these cubes — often seen as part of the Nazi nuclear effort, as two-inch blocks of natural uranium are difficult to come by — have never been officially confirmed to be left over from Hitler’s atomic project.
Three such cubes are now being studied by the Pacific Northwest National Laboratory in Washington, one of the U.S. Energy Department’s national laboratories, which hopes to prove the uranium’s origins once and for all.
The United States launched a covert mission in 1943 called Alsos, attempting to peer at Germany’s notes to see how far the nation had gotten. Both sides prepared for doomsday, though the mission would eventually show how far German physicists were from success.
History could have been disturbingly different, some historians argue, if the following events did not occur: The German nuclear program deflated as scientists lost hope and governmental support. Then the Americans, successful in their mission, created — and dropped — a workable atomic bomb.
Werner Heisenberg, the German physicist perhaps most infamous for his involvement in Nazi Germany’s nuclear program, had headed experiments that were hidden away in a cave under a castle as Allied forces closed in, including the final iteration of the experimental reactor that came the closest to being successful.
A paper in Physics Today called the experiment, made of 664 uranium cubes, an “ominous uranium chandelier,” strung together in long chains by aircraft wire and encapsulated by heavy water and a wall of graphite.
The Nazis failed, but they had hundreds of cubes of uranium, each about the height of a golf tee. Heisenberg is believed to have escaped on a bicycle, his backpack stuffed with cubes of the heavy metal, before the Allies arrested his scientists and interrogated them in an effort to find out the reactor’s location.
Many of the cubes have been lost to time. But after the war, some of the Nazis’ uranium was folded into the United States’ own nuclear efforts. Some wound up in the hands of private collectors. And some is probably sitting in labs, waiting on final confirmation that it was, in fact, connected to Hitler’s regime.
Professor Tim Koeth from the University of Maryland sent the Pacific Northwest National Laboratory samples of two cubes, and it’s unclear how the third ended up in Washington. It has been at the lab longer than its lead researcher, and only anecdotes and guesses remain about how it arrived.
Researchers at the Pacific Northwest National Laboratory are aiming to confirm the pedigree of the cubes and hopefully identify the German research group to which they belonged. The Nazis’ effort to achieve nuclear supremacy was splintered into distinct subgroups, including those headed by Heisenberg and Kurt Diebner.
Though one of the cubes has been at the lab for more than 15 years, said Jon Schwantes, the project’s principal investigator, there’s little information about how it arrived there. Most think it was among those confiscated from the Nazis at the end of the war, he said.
Brittany Robertson, a doctoral student who works at the lab, has been pioneering new analytical techniques to determine the uranium’s origins.
“It’s somewhat surreal,” she said, “and certainly an honor.”
In 1939, Albert Einstein wrote to warn President Franklin D. Roosevelt of the possibility of the Germans developing an atomic bomb, and the Manhattan Project kicked off a few years later. Though it predated the Cold War days of teaching children to duck and cover under school desks in the event an atomic bomb was dropped somewhere in the nation, the fear of nuclear arms — and the possibility of them ending up in Nazi hands — was already palpable.
Scientists fleeing as refugees and overall dysfunction may have stopped the Nazis from beating the United States in the race to nuclear power. Instead of pooling resources and keeping science close to government, they distanced the sectors and split up their researchers, hoping to inspire competition.
“The reasons for the delay were varied and complex and included fierce competition over finite resources, bitter interpersonal rivalries, and ineffectual scientific management,” the 2019 study in Physics Today noted.
The U.S. voyage toward nuclear knowledge was built on fear, Robert Furman, former chief of foreign intelligence in the Manhattan Project, said in a 2008 interview. Furman, who rode alongside Little Boy’s uranium ore across an ocean, was part of the Alsos Mission.
The United States knew Germany had a head start on nuclear research. It was unclear how far ahead the nation was, and anxieties brewed in that uncertainty.
“I think everyone was terrified that we were wrong, and the Germans were ahead of us,” Manhattan Project physicist Leona Marshall Libby recalled in a 1986 interview. “Germany led the civilized world of physics in every aspect, at the time war set in, when Hitler lowered the boom. It was a very frightening time.”
Leslie Groves, head of the Manhattan Project, launched the covert mission known as Alsos in 1943, intending to discover what was happening in Germany’s science realm — namely how far the Germans were from creating a successful atomic bomb. More than 600 uranium cubes similar to the one now at PNNL were recovered as a part of the mission.
Though solidifying the cubes’ pedigree is the focus of Robertson’s research, Schwantes said material from the cubes is also being used for more directly practical purposes, such as training border guards to detect uranium and helping stop nuclear proliferation and terrorism.
The juxtaposition of the cube’s probable origins to its more recent fate is not lost on Schwantes.
“This cube, potentially coming from Nazi Germany’s nuclear program for the purpose of trying to produce plutonium for their weapons program, is now being used at PNNL for training purposes … in an attempt to make the world a safer place,” he said. “So it’s an interesting history.”
Robertson, who presented on the methods being used to date the cubes Tuesday at the fall meeting of the American Chemical Society, said the project is at least a few months from completion if everything goes according to plan.
Robertson will continue the hours of tedious lab work that could unveil secrets of the Nazi war effort — and offer insights into the origins of the heavy metals that could have changed history and mercifully did not.