In 1981, while on a trip to China, Ava Helen fell ill; before the year was over, she died of stomach cancer. Gone was Linus's beloved wife of over fifty-eight years, his "constant and courageous companion and coworker." It was a blow from which Pauling, who lived an additional thirteen years, would never fully recover. Increasingly he sought solace in the solitude of his Big Sur ranch and in the web of calculations that informed his scientific research. As he noted in an interview nine years after her death, "since my wife died...I don't have anything to do now, except make discoveries and write papers." But through it all Pauling refused to give up his political activism entirely.

Shortly after Ava Helen died, Linus once again hit the road, delivering a steady stream of speeches on peace and world affairs, endorsing a nuclear-freeze campaign, and decrying the senseless militarism of a new president -- the actor he had once, long ago, discussed politics with at the Brown Derby, Ronald Reagan. Pauling decried Reagan’s "senseless militarism" and the scientific folly of his attempts to erect an anti-missile shield against nuclear attack, a program that the press dubbed "Star Wars." In 1984 he traveled by sea with fellow Nobel Laureate George Wald aboard a "Peace Ship" on a humanitarian mission to Nicaragua. In 1986 he spoke in Hiroshima on the anniversary of the atomic bombing that had so galvanized him forty-one years earlier. In hundreds of public appearances throughout the 1980s he made good on his promise, first issued in 1947, to "include mention of world peace in every lecture and address that I give."