Authors: David Bodanis
E=mc2 (16 page)
"All that day Serber amused herself and the women who worked for her by saying to innocent would-be readers 'Please move these little packages to the next table for me.'
But they couldn't move the one that came from Fort Knox. Gold is denser than lead (that's why it was chosen), and the little 6-inch solid gold sphere inside weighed as much as an eighty-pound barbell.
But yet, despite the dozens of top researchers and the nearly unlimited funds, the plutonium problem still wasn't being solved. Was it possible, Oppenheimer and others worried, that no full bomb could be made this way? In that case, the best that might result would be an accumulation of radioactive plutonium. Maybe that was even what Heisenberg's heavy water reactor was being designed to cook up. Oppenheimer was informed, in a memorandum of August 21,1943:
It is possible . . . that [the Germans] will have a production, let us say, of two gadgets a month. This would place particularly Britain in an extremely serious position but there would be hope for counteraction from our side before the war is lost. . . .
One of the memo authors was Teller, who could be discounted, but the other was Hans Bethe, an eminently sensible man. He was the head of the theoretical division at Los Alamos, and he'd been a faculty member with Geiger until 1933 in Tubingen. He had excellent contacts with physicists who'd remained on the Continent. The "gadgets" Bethe and Teller had in mind were full bombs, which were unlikely at this stage, but who knew what else the Germans might build?
Even a few pounds of powdered radioactive metal released over London could make parts of that city uninhabitable for years. There already were worrying reports of the advanced delivery weapons Germany was working on, and one of Heisenberg's men was later seen at Peenemtinde, where the supersonic "vengeance" weapon—the V-2 missile—was being built. Much simpler jet drones were also being constructed—the V-is—and if those crashed highly radioactive warheads into Allied troop emplacements, in the south of England before D-Day or in France afterward, there could be casualties of a level that had never before been seen.
The threats were taken so seriously that Eisenhower accepted Geiger counters, and specialists trained in their use, to be ready to go with his troops building up in England for D Day. And then, at the very end of 1943, when Oppenheimer was most lost in the plutonium implosion problem, Niels Bohr arrived at Los Alamos, after an escape from his institute in Copenhagen. Bohr was the kindly elder statesman of physics. Over the years everyone who counted, from Heisenberg to Oppenheimer to Meitner's nephew Robert Frisch, had stayed at his institute and worked with him.
Now Bohr brought serious news. On December 6— after he'd fled—German military police had invaded his institute. They hadn't managed to steal the Nobel gold medals stored there, for George de Hevesy had dissolved them in a jar of strong acid, and left them—in liquid suspension—unobtrusively on a back shelf. But they had bullied their way around, arresting one of Bohr's colleagues who lived in the building. Most seriously, there were rumors that the institute's powerful cyclotron, an early form of particle accelerator, was going to be broken apart and sent back to Germany. Cyclotrons can make plutonium.
And then British military intelligence reported that, despite the sabotage and even a later Allied bombing raid, the factory at Vemork had been restarted. I. G. Farben engineers had been working frantically to repair it: replacement parts had been hurried in, and production now was higher than ever. In February 1944 the Norwegian Resistance reported that the entire heavy water stock was about to be sent back to Germany.
What to do? It was an excruciating moment, previewing the dilemmas the Allied physicists would face in the decision to use the bomb one year later. Another direct assault wasn't possible, for the Vemork factory was too heavily barricaded. The main train tracks out were heavily guarded as well—there were regular Army troops; SS detachments; auxiliary airfields that would be opened for spotter aircraft.
The sole weak spot for attacking the shipment back to Germany was where the train cars with the heavy water from Vemork had to be loaded onto a ferry to cross Lake Tinnsjo, on their way to the Norwegian coast. That was scheduled to take place in mid-February 1944.
If the train was sunk while it was on the ferry, no German divers could bring it up from the lake's depths. But Tinnsjo was also the main crossing to the rest of Norway for the factory workers at Vemork plus their families; it was also a popular tourist crossing. Ordinary families out for the day always were on the ferry.
Whom do you kill for a greater good?
Because of the equation—these powers E=mc
2
was offering—the physicists were demanding an awful moral trade-off, greater than anyone should be required to make. Knut Haukelid was one of the Norwegians who had remained behind after the factory raid, living rough on the Hardanger plateau, surviving massive manhunts. By now he was very experienced at the skills needed for sabotage: smuggling himself into a town; working out whom to trust; assembling and testing whatever explosives and timers would be needed. But that wasn't the issue. He had traveled this far, and lived this harshly, to save his countrymen. Now he would be killing them, drowning them in deep cold water.
Norway command to London:
REPORTS AS FOLLOWS: . . . DOUBT IF RESULT OF OPERATION IS WORTH REPRISALS STOP WE CANNOT DECIDE HOW IMPORTANT THE OPERATIONS ARE STOP PLEASE REPLYTHIS EVENING IF POSSIBLE STOP
London to Norway command:
MATTER HAS BEEN CONSIDERED STOP IT IS THOUGHT VERY IMPORTANT THAT THE HEAVY WATER SHALL BE DESTROYED STOP HOPE IT CAN BE DONE WITHOUTTOO DISASTROUS RESULTS STOP SEND OUR BEST WISHES FOR SUCCESS IN THE WORK STOP GREETINGS
The best Haukelid could do was arrange with the Vemork transport engineer that the shipment would only come out on Sunday the 20th, when traffic would be light. (Trade union activity had always been strong in Vemork, and as a result the Resistance had high membership—and higher support—in the factory.) Late the Saturday night before, Haukelid arrived with two locals at the berthed ferry. They got on board safely, but when they were hunting for a spot below-decks to lay their explosives, the night watchman, a young Norwegian, found them. He knew one of Haukelid's companions, though, from a local sports club, and quickly nodded his agreement when they gave him their cover story: that Haukelid and the other man, Rolf Sorlie, had to hide from the Germans, and needed somewhere to store their packages. While the first two men stayed behind talking, Haukelid and Sorlie set the charges: right against the front hull, so the explosion would tip the boat forward, lifting the propeller uselessly up in the air, and would cause the tipped boat to fill with water and sink immediately. It was a half hour before Haukelid was done.
When I left the watchman, I was not clear in my mind as to what I ought to do. . . . I remembered the fate of the two Norwegian guards at Vemork, who had been sent to a German concentration camp after the attack there. I did not want to hand over a Norwegian to the Germans. But if the watchman disappeared, there was danger of the Germans' suspicions being aroused next morning.
I contented myself with shaking hands with the watchman and thanking him—which obviously puzzled him.
Lake Tinnsjo ferry
NORSK HYDRO
Everyone involved was in Haukelid's position. Alf Larsen, chief engineer at Vemork, had been at a dinner party earlier that evening, where a visiting violinist said that he'd be taking the boat the next day. Larsen had tried to say no, that he should stay longer in this beautiful region, the skiing was so excellent. But when the violinist waved that off, Larsen hadn't been able to insist. A contact at the factory had told him that his elderly mother, too, was planning to take the ferry.
The bomb went off at 10:45 A.M.; the boat was in 1,300 feet of water. The flatcars from the train broke loose in the sudden tilt, their doors bursting open. The factory worker's mother wasn't on board—her son hadn't let her out of the house—but the violinist was. There were fifty-three people on board. Most of the sturdy German guards managed to fight their way off the tumbling ship in time, but many of the women and children were pushed aside. Over a dozen passengers were caught inside.
A few of the barrels that had been only slightly purified bobbed on the top of the lake, and the passengers who'd managed to get off but hadn't made it into lifeboats—although the violinist did—grabbed on till a rescue boat came. But the barrels that contained the concentrated heavy water demonstrated, in slow-motion free fall, what they contained. Since the H 2 0 molecules are composed of a nucleus heavier than ordinary water, the barrels sank as if weighted, swirling around the ferry and its innocent trapped passengers down to the bottom.
One year and six months later, in August 1945, 50 pounds of purified Uranium 235, encased within 10,000 pounds of cordite, steel tamper, casing, and firing controls, was waiting on a heavy trolley, about to be loaded onto a B-29 on the island of Tinian, six hours' flying time from Japan. Oppenheimer was back in Los Alamos, monitoring this final operation.
If he were a simpler man, he might have been proud. The construction "machine" of researchers and factories and assembly units, which Heisenberg had abortively tried to put together in Germany, had here—on American shores, and under Oppenheimer's direction— finally been achieved. Rivers had been tapped to supply the processing plants and reactors; whole cities had been built to house tens of thousands of workers; a new element had been created through transmutation. It was an immense achievement.
Fermi's first neutron source, the one he'd used in Rome, based on Chadwick's design, could be held on the palm of one hand. The next device Fermi built, scraping together minor funds in New York in 1940, was about the size of a few large filing cabinets. By late 1942, with Oppenheimer overseeing the first substantial U.S. government funding, Fermi had built an enhanced device that filled much of a competition squash court, underneath the stands of the University of Chicago stadium. The final versions, constructed two years later, when atomic bomb funding was at full tilt, were the centerpieces of a 300,000-acre site in central Washington, near Hanford. With their supporting structures, they stretched taller than the entire Rome institute where Fermi had begun in 1934. Individuals who were aware of the full history could only stand in front of it in awe.
The plutonium problem had been solved, through mathematicians and explosives experts finding a shape for the ordinary explosives that would smoothly implode the plutonium ball. Regular supplies of the Washington site's output could now be machined for more bombs. The less successful Tennessee factories had also managed to produce a small amount of explosive, and it was Tennessee's total output—almost the complete amount of U
235
the United States had—that was being loaded on Saipan.
Heisenberg's work had been blocked. Earlier in 1945, advancing Allied armies in Germany had found entire factories, some underground, with row upon row of completed jet-powered and even a few rocket-powered aircraft. But the Lake Tinnsjo sinking the previous year had guaranteed that only the barest amount of atomic construction could continue going forward. Even so, Heisenberg had tried to continue. Back in 1942, when funding had looked like it might slow down, he had eagerly explained the possible power of an atomic bomb to a conference of top Nazi administrators, in a quest to get funding back up. Now, even with the war near certain to be lost, he directed that the work be carried on from the small town of Hechingen, where he ended up lodging directly across the street from the home where Einstein's rich uncle had lived—the one who'd supported the family's business efforts, thereby giving Albert the subsidized years to prepare for university entrance.
The equipment lugged from Berlin and Leipzig had been ingeniously installed
in
a place observation planes wouldn't be able to find. It was put in a cave in an adjacent town, and the cave was in the side of a cliff, and on the top of the cliff was a church—and that was all you would see from the sky. Heisenberg had always been the one for grand gestures. When he'd first conceived of quantum mechanics, one night on a North Sea resort island at age twenty-four, he'd climbed the nearest dune peak and waited there till dawn, copying the Romantic characters from a Caspar David Friedrich painting. Now, in occasional excursions from the cave, he would climb to the highest point in the town, and go into the church, and there in his solitude play Bach with eloquent fury on the organ.
The atomic reactions had gone well beyond the old Leipzig work. By the end, the German researchers had reached about half the rate of nucleus splitting needed for a sustained chain reaction. Heisenberg knew he wouldn't get further. When a U.S. snatch squad did reach him in the Alps, even while Wehrmacht troops were still fighting in adjacent towns, he accepted surrender as if he'd been expecting it.
