Fifty years ago Wednesday, a middle-aged man, prematurely balding and with a pronounced Italian accent, rented a room at International House, a dormitory at the University of Chicago.
The registration form asked guests to list any academic awards or scholarships they had earned.
”Nobel prize for physics 1938,” wrote Enrico Fermi, who shaded the truth when he came to another question asking what he`d be doing during his stay at the university. He`d be working, Fermi answered, in the
”metallurgical laboratory,” a little misinformation dictated by the need for wartime secrecy. Two months before, the Japanese had bombed Pearl Harbor.
In reality, Fermi, a refugee from Mussolini`s fascism, had come to Chicago from Columbia University to head a clandestine research team operating out of improvised quarters under the stands of Stagg Field, the university`s football stadium.
There, Fermi soon completed the critical experiment in the development of the atom bomb, leading mankind into the nuclear age.
The world will celebrate the golden anniversary of that milestone on Dec. 2. But in Chicago, the atomic era really began when Fermi arrived in February bearing military orders to translate nuclear fission from a scientific curiosity to a weapon of war with unparalleled power.
”Our objective was to establish a chain reaction, which is the equivalent on the atomic level of what happens when you put a match to a pile of twigs,” recalls James Sturm, 75, one of a handful of surviving members of Fermi`s team. ”At first, you have to hold the match in place just to keep a tiny flame going. But finally the wood catches fire, then keeps on burning of its own accord.”
To translate that analogy into the world`s first atomic reactor, a group of scientists assembled in Chicago whose ranks included several Nobel Prize winners and winners-to-be.
Sturm was a young graduate student when Fermi interviewed him for a job while the celebrated physicist was running blocks of graphite through a band saw.
”I could scarcely see Fermi behind a cloud of thick, black dust as he explained the project to me,” Sturm recalls. ”That`s how science was done in those days. A scientist was expected to build his own lab equipment.”
That graphite was a ”moderator” designed to slow down neutrons, sub-atomic particles given off by uranium atoms as they are split. It had been discovered that slow-moving neutrons have a better chance of striking and splitting still other atoms, thus producing a chain reaction.
”The trick was to achieve a chain reaction but not one that would run dangerously out of control,” Sturm says. ”Because then the uranium pile might go into a meltdown, producing a big, radioactive mess.”
In retrospect, the Chicago team`s contingency plans seem a bit naive. For Fermi`s final experiment, a ”suicide squad” of graduate students was positioned above stacks of uranium armed with bottles of a neutron-absorbing sodium solution to be poured over the pile if it ran wild. As Sturm now calculates the variables, the liquid would have reached the radioactive material too late to prevent disaster. But Fermi`s associates were so in awe of his genius that they were willing to go wherever he led.
”Fermi didn`t have a single physics book in his office,” Sturm remembers. ”He didn`t need any. He carried most of the equations in his head. Those he didn`t, he could mathematically derive, on the spot, whenever he needed to plug them into the little five-inch-long slide rule he did all his calculations on.”
Sturm recalls that, one day, someone brought a kind of jig-saw puzzle to their improvised lab. Unlike a child`s puzzle, all its pieces were rectangular and it lacked any design as a clue to its assembly. Everyone tried their hand, the results running from a fast time of 30 minutes to a senior scientist who, after two hours, threw up his hands in defeat.
”We showed the puzzle to Fermi as he was eating lunch,” Sturm says.
”He took one look at the pieces and assembled them in 30 seconds, flat.”
The project hidden under Stagg Field`s stands was driven by something more than intellectual curiosity. In early 1942, it seemed the United States and its Allies needed a miracle weapon to win World War II. Fermi and his associates were also haunted by fears that an atomic bomb was being developed in Nazi laboratories. A German physicist, Otto Hahn, had already demonstrated the uranium atom could be split with a resulting release of energy.
In 1939, Leo Szilard, one of Fermi`s associates, had persuaded Albert Einstein, the world`s most famous scientist, to write a letter to President Franklin D. Roosevelt expressing the physicists` conviction that America could not afford to finish second in the race to develop an atomic bomb. As a result, the U.S. Army eventually assumed control of nuclear research.
When the resources of the nation`s campuses were enlisted into the war effort, the University of Chicago was assigned the job of solving a key part of the puzzle of how to make a bomb.
During the spring and summer of 1942, Fermi`s associates in Hyde Park tested various ways of arranging graphite, uranium and cadmium control rods into a ”pile,” the group`s working name for what would later be called an atomic reactor. As cadmium absorbed neutrons, it was expected to prevent the pile from producing atomic fission at too great a rate.
By November of `42, the group was ready to build the final pile. Slowly stacking up layers of graphite and uranium, the scientists took daily readings with a Geiger counter of the level of radioactivity as Fermi, using his pocket slide rule, calculated the pile`s ”critical mass”-the level at which it would produce a self-sustaining chain reaction.
On Dec. 2, 1942, the group assembled for the pile`s final test. Sturm was standing alongside Fermi near the main control panel as the Italian physicist ordered the last cadmium rod pulled slowly out of the pile.
”Late in the morning, a control rod designed to automatically slam back into the pile if something was wrong suddenly slammed home,” Albert Wattenberg, 75, recalls. ”It was only a false alarm. The rod had been incorrectly set, but (after that) Fermi decided maybe we needed a break for lunch.”
Afterward the experiment continued, with Fermi ordering the rod pulled back a few more inches at a time, as Geiger counters clicked faster and faster. Finally, at 3:36 p.m., Fermi closed his slide rule, smiled broadly and announced the pile was producing a chain reaction. He let the pile run on for another 28 minutes before ordering it shut down.
Then Eugene Wigner, a Hungarian-born physicist, produced a bottle of Chianti wine and some paper cups. The group drank a silent toast to its success and those present signed the bottle as witnesses to man`s first harnessing of atomic power.
After completing his breakthrough research in Chicago, Fermi and his associates were transferred to a government laboratory in Los Alamos, N.M. There they applied their findings to development of the first atomic bomb, which was exploded in a test at the nearby Alamagordo Air Base on July 16, 1945.
Following the war, Fermi returned to the University of Chicago, where he continued his teaching and research. He died at his home in Hyde Park, of cancer, on Nov. 28, 1954. He was 53.
The site in Hyde Park where that first leap into the atomic age was made has been marked with a Henry Moore sculpture. But at the time, some of Fermi`s associates recognized the historical significance of the moment. One of them, Arthur Compton, was inspired to reach for a metaphor when he phoned colleagues at Harvard to report Fermi`s success, using language that would not compromise security.
”The Italian navigator,” Compton said, ”has landed in the New World.”
