What do we learn about Mr Loomis’ background in chapter 6&7

Ann finds out a little bit about the man: his name is John R. Loomis, he is a chemist from Cornell University, and he is an expert on radiation and the physical sciences. He feels much better the next morning (on May 29). Ann makes him a hearty breakfast, and notices that he is sitting up in the doorway of the tent. Loomis is baffled by Ann’s ability to survive for a year by herself in the valley. She tells him about how her parents drove away and never came back. Loomis notes that it was nerve gas that killed most people: they went to sleep and never woke up. It had taken him ten weeks to get from Ithaca to the valley, and all that way, all that time, he had seen no people, animals, trees, or insects. He says that he was ready to give up but then finally came over the ridge and saw, in the late evening, a haze of blue.