No trace remains today of Stagg Field, the old football stadium at the University of Chicago where, 50 years ago Wednesday, the atomic age was born. What stands now on the site, on Ellis Avenue between 56th and 57th Streets, is an abstract sculpture by Henry Moore. If it resembles anything at all, it looks like a mushroom cloud.
That is the legacy that continues to haunt what in all other respects was an outstanding scientific achievement. Using laughably simple materials, such as blocks of graphite and metal rods that were pushed and pulled by hand, a group of scientists on Dec. 2, 1942, unlocked the power of the atom and then, just as important, relocked it before it became dangerous.
The 43 scientists on hand, who were led by the Italian refugee Enrico Fermi, had achieved the first controlled nuclear reaction.
”We all knew in principle that we had here a very significant milepost if we could make it work,” recalled physicist William J. Sturm, one of those present. ”We knew that all of man`s energy that he had used for work and power and heat had derived from the sun until that day. We knew that now we could get energy from a new source.”
The University of Chicago is commemorating the 50th anniversary of the first controlled reaction with an exhibit through Feb. 5 at the university`s Regenstein Library, 1100 E. 57th St. And a university-sponsored symposium Wednesday afternoon will focus on the event and Fermi.
Also, a memorial will be held at 10 a.m. Wednesday at the sculpture to remember those killed by atomic blasts and radiation.
Afommonwealth Edison`s 12 reactors, the most of any American utility.
Because of that first nuclear reaction, diseases can be diagnosed with radioactive materials, and cancer can be treated with radiation. Fires can be discovered by smoke detectors that contain bits of radioactive material.
But the power of the atom remains frightening and controversial. Old fuel rods from nuclear plants pile up as the federal government tries to figure out a safe way to dispose of them. Concern about the way Edison runs its Zion and Dresden plants has led the Nuclear Regulatory Commission to place them on its watch list of troubled plants.
Most worrisome of all, thousands of nuclear warheads still exist despite the end of the Cold War. They are the most direct descendants of the experiment that came to a head shortly after 3:30 p.m. on that bitterly cold day 50 years ago.
America had been at war for a year. Japan and Germany were at the height of their power, their armies and navies having bloated their empires with conquered peoples and battle-scarred territory. It was not known then that their tide had already begun to ebb. What was known was that German scientists were trying to develop a new bomb based on the atom that would dwarf the most powerful bombs in existence.
As part of the allied countereffort, Fermi and his colleagues had labored throughout 1942 to find a way to unleash the energy of a split atom without setting off an uncontrolled chain reaction.
Their laboratory was a doubles squash court beneath the west grandstand of Stagg Field, which had become decrepit since the Maroons, the university`s football squad, had been disbanded.
Starting on Nov. 16, scientists assembled on the floor of the squash court alternating layers of plain graphite bricks and layers of graphite bricks that held balls of uranium. Fermi dubbed the assemblage ”Chicago Pile No. 1.”
In a chain reaction, the nucleus at the heart of an atom of uranium splits and shoots out subatomic particles, many of which strike other uranium nuclei and split them. By surrounding the uranium balls with graphite and inserting bars of cadmium between some of the layers, the scientists calculated that they could turn on and switch off a chain reaction, a critical step in proving that atomic energy could be harnessed and used.
But graphite is a messy material. While the work was in progress, the squash court was filled with black dust, and a slippery film coated faces, walls and floors.
”I guess I filled out 30 accident reports for the kids,” said Albert Wattenberg, one of the young scientists who worked on the pile. ”People were always slipping and falling and hurting themselves.”
In addition to the graphite dust, an unusually cold late fall also made the work in the unheated squash court miserable. Someone found a cache of old raccoon coats that football players had once used.
By the morning of Dec. 2, the roughly spherical structure and its supporting wooden frame was complete. It was made of 771,000 pounds of graphite and almost 92,990 pounds of uranium-containing spheres.
Throughout the morning, Fermi instructed physicist George Weil to withdraw a control rod a few inches at a time. Then he calculated the speed of the resulting reaction. Perched on a scaffolding over the pile were three scientists who held jugs of a solution that was to be poured on the pile if the reaction got out of control.
About 11:30 a.m., an improperly set safety device was triggered and the pile shut down unexpectedly. Fermi took that as a clue to break for lunch.
Work resumed in the afternoon. As Loop office workers began to anticipate another rush hour of crowded trains and streetcars-the result of gas rationing, which forced many people to give up driving to work-Fermi fiddled with his 6-inch slide rule a final time and told Weil to withdraw the control rod another 12 inches.
A recording device traced a steep line, signifying that the reaction had figuratively caught fire and would sustain itself.
”The pile has gone critical,” Fermi announced, an utterance that may not rank with ”Eureka!” among notable scientific quotes, but one that signaling the beginning of a new era.
About 20 minutes later, control rods were inserted, and the reaction shut down.
”There were no fireworks, no flashing lights, no sign that goes up,”
said Albert Wattenberg, now 75 and a professor emeritus at the University of Illinois in Champaign-Urbana. ”There was no cheering. People smiled and perhaps a few patted each other on the back, and that was about it.”
Eugene Wigner, a Hungarian refugee, opened a bottle of Chianti he had bought for the occasion. The scientists drank the red wine out of paper cups and signed the bottle`s straw holder.
The bottle, signed by those present, is part of the Chicago Historical Society`s ”Chicago Goes to War” exhibit.
Another Hungarian scientist, Leo Szilard, stayed behind with Fermi on the balcony overlooking the squash court after everyone else had left.
”I shook hands with Fermi,” Szilard recalled later. ”And I said I thought this day would go down as a black day in the history of mankind.”
Soon after the first reaction, scientists moved the work on the atomic bomb to a secret laboratory near Los Alamos, N.M., and in August 1945, the first and only atomic bombs to be used in war were detonated over Japan.
World War II ended, but the debate about nuclear energy had only begun. For Sturm and Wattenberg, the peaceful purposes of nuclear power outweigh the harmful uses and side effects, which they say have been exaggerated.
”It`s rather abstract, you see, nuclear energy,” said Sturm, now retired and living in Western Springs after a career in nuclear research.
”People don`t understand it, but then, I don`t think people understand fire very well, either.”