What was John Loomis' past like?

Mr. Loomis tells Ann that he was a graduate student at Cornell, studying organic chemistry, specifically plastics and polymers. The head of his department, Professor Kylmer, was a Nobel Prize winner and worked part time at a special government laboratory near Cornell. The lab was a secret, but eventually invited Mr. Loomis (Ann begins calling him this) to work at the lab. The government was attempting to develop radiation-proof suits – like the one he was wearing. This was three years before the war. After the war, he spent three months in the underground lab, hoping that radiation levels would go down. They did not, and so he began a series of expeditions – eventually ending up in the valley.