As 1942 began, Chicagoans knew two things for sure: the nation was at war, and the war news was bad.

Some tried to escape their worries by going to the Chicago Theater to hear Xavier Cougat and his rumba band, or by catching Fred Allen on WBBM, Jack Benny on WMAQ, or "The Wishing Well" on WGN.

You didn't need "Inner Sanctum" or "The Whistler" to scare you when survivors and reports continued to arrive from the surprise attack on Pearl Harbor, less than a month before. Or when the rationing of tires and gasoline hit. Chicago's monthly allocation of tires - less than 8,000 for the entire city - meant that driving for any nonessential purpose was out of the question.

But the city rose to the occasion. Young men besieged recruiters, trying to enlist. At the Gary and South Chicago steel mills, workers stopped and cheered the new year at midnight, then resumed extra shifts. At the height of production Americans would be turning out one plane every eight minutes, a tank each half hour and three ships a day.

While Marshall Field's advertised $6.95 Nunn-Bush shoes and $1.95 dress shirts, Carson Pirie Scott suggested a sensible "Feathered Bob - Shiny Ringlets of Curls, Easy to Keep" for $1.95.

Papers profiled war bond buyers. Greyhound advertised "Visit Your Soldier in Camp" tickets to New York, $12.35. The Uptown Theater featured Gary Cooper in "Sgt. York."

Still, the future looked bleak. One headline read, "Pacific War could be over in 5-10 years." But two big events which would shape the future started almost unnoticed.

Occupational deferment ended. By year's end 2 million women would be working in factories, freeing men for fighting and making "Rosie the Riveter" a key part of the war effort. Ideas of what women could and could not do changed in fundamental ways.

In a squash court underneath the Stagg field bleachers in Hyde Park, Enrico Fermi and his band of scientists huddled over a pile of "eggs" made of uranium. In December 1942, they succeeded in making a "chain reaction" and changed our lives forever.

A chain reaction means that if you get enough uranium close together, when one atom splits (which radioactive atoms like uranium do naturally), the pieces which come off can hit other atoms, causing two more to split into four, and those four into eight, and so on.

So what's the big deal? Well, if you took a chessboard and put one grain of rice on the first square, and two on the second, and four on the third, by the time you got to the last square it would hold 2,000 tons of rice for every man, woman, and child in the United States. If you would do that with uranium, you would create the most powerful bomb humanity had ever seen.

Now, the atom-splitting in Chicago was controlled, but the principle was proven, and soon the Manhattan Project was building the atomic bombs that would end the war and send us all into the nuclear age.

Three years later, half a world away in the Philippines, Bob Duncan prepared to invade the Japanese homeland. He asked his sergeant, "What do think about that story of some super bomb making the Japanese surrender?"

"Come on Duncan, it's a bunch of propaganda to make us feel better. This enemy won't give up. We may suffer 500,000 casualties, but they'll suffer more."

Well, the sergeant was wrong. My father missed his "D-Day" and lived to tell me his story. He showed me his Japanese phrase book which begins, "Throw Down Your Rifle!" Now I sit here in the warm Australian sweater issued to him for the invasion.

Doug Duncan is a professor of astronomy at the University of Chicago.

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