The questions of free will and determinism in a universe which may be subject to entropy are most sharply defined by Pynchon in his longest and most complete novel, Gravity’s Rainbow. Set in the closing days of World War II and the months immediately following the end of the war, this novel takes the themes and techniques of the two earlier novels to higher levels. Gravity’s Rainbow—in part because many regard it as a masterpiece and in part because it is so complex, involves so many strands of action, and poses so many unanswered questions—has been the subject of more critical attention than any novel in English since James Joyce’s Ulysses (1922).

The central symbol of Gravity’s Rainbow is a new type of rocket developed by the Germans at the end of World War II, designated the A-4. The first rocket designed to carry a human being into space, it is a triumph of technology. It suggests the possibility that humankind may have found a way to transcend its earthly origins, but it is much more likely that it carries beyond previous limits—beyond any limits—people’s ability to destroy themselves. Technology, in Pynchon’s view, has a capacity for destruction that threatens to overwhelm its capacity for construction. At the beginning of the novel, a screaming in the sky seems to indicate that a rocket is on the way; at the very end, the reader sits in a theater with a descending rocket poised just overhead.

The action of Gravity’s Rainbow centers on attempts to trace the A-4 rocket and its components, especially an advanced form of plastic called Imipolex-G. The British, the Americans, and the Russians, nominal allies in the war against Adolf Hitler’s Germany, are rivals in trying to find the rocket and its makers in order to gain an advantage in the postwar world. One part of the British effort is managed by a behavioral scientist named Ned Pointsman.

Pointsman is the spokesman in the novel for the Pavlovian idea (named for the Russian psychologist Ivan Pavlov) that people, like all other animals, act in response to stimuli. Pointsman believes that if the correct stimuli are applied, anyone can be trained to undertake any action his or her controller directs. He makes use of the fact that an American lieutenant named Tyrone Slothrop (he is, incidentally, the younger brother of Hogan Slothrop in “The Secret Integration”) was the subject of an early experiment in conditioning a young baby. The experimenter, a mysterious figure named Lazslo Jamf, who also invented Imipolex G, supposedly removed “Baby Tyrone’s” early conditioning, although remnants of it apparently remain.

Using a variety of behavioral methods, Pointsman sets Slothrop on the track of the A-4 rocket, and for much of the first half of Gravity’s Rainbow, Slothrop is the center of the action. He moves from London to the French Riviera to Switzerland. When the war ends he moves into the “Zone,” an area geographically similar to the British, American, French, and Russian zones of occupied Germany but much larger, symbolically encompassing all the postwar world. Slothrop has a variety of adventures, some frightening, some hilarious.

Other characters are involved in their own quests for the rocket. The Hereros, remnants of a tribe transplanted to Germany years before from what was (before World War I) German Southwest Africa, have assisted in work on the rocket and now search for leftover parts to construct a rocket for themselves. Their leader, Enzian, is convinced that the rocket will provide a new center for the tribe, without which it will wither away. Enzian’s path crosses Slothrop’s from time to time. So does that of the chief American searcher, Major Marvy, a gross and vicious scout not only for the American armed forces but for American industrial interests as well. All of them, at one time or another, encounter the Soviet agent, Tchitcherine, who happens to be Enzian’s half brother.

There are dozens of other characters and other plots involved in the novel. Countering Pointsman is a British officer named Roger Mexico, a mathematician who rejects Pointsman’s determinism and argues that traditional Western ideas of cause and effect are too limited. In his view, new scientific ideas about chance and indeterminacy are more important. Mexico’s affair with a member of the British WAAF (Women’s Auxiliary Air Force) named Jessica Swanlake is the nearest thing the novel contains to a love story. It ends when the war is over and Jessica chooses a more conventional man. A British secret agent called Pirate Prentice is also involved, along with one of his spies, a Dutch woman named Katje Borgesius.

While these characters (and many others) are engaged in their quests, the novel also recounts the story of the German characters who built and launched the rocket. Chief among these is the sinister Captain Weissman (also known as Blicero), who was responsible for assembling the men with the special skills needed to create and build the rocket. Once the rocket was launched, he evidently died. He has been Enzian’s lover. One of his aides is a scientist named Franz Pokler, who is forced to keep working on the project because his wife, a radical, and his daughter are being held in a prison camp; if he fails to cooperate, they will presumably be killed.

Entropy is less important in Gravity’s Rainbow than in Pynchon’s earlier work; it still operates, but it seems to be less an immediate threat than the nuclear weapons that could destroy the known world in a few minutes. Paranoia, however, is more important than ever. The novel includes many episodes in which characters’ suspicions that they are involved in some gigantic plot are supported by all the available evidence. The most perceptive characters have frequent intimations that there is a group called only “They,” which is international in scope and which intends to gain control over everything: people, resources, and ideas. At one point, for example, Enzian experiences a revelation that all the destruction caused by bombing and shelling in World War II has been specifically planned to wipe out the old industrial establishment in order to make way for a new and more efficient physical plant.

There are small rays of hope. Art provides an alternative to the regimentation of modern society. Rebellion is still possible; when Slothrop disappears, his friends and supporters form a group called the “Counterforce” to oppose “They.” The Counterforce inevitably becomes bureaucratic and public relations-oriented, but members are capable of individual acts of defiance which can provide hope. The style of the novel, varied and spectacular, is itself the strongest denial of the grayness and blandness that result from the control of society by those who use technology for their own ends. At the end of the novel, however, destruction seems to be inevitable.