Doctor Manhattan was born Jon Osterman in 1929. His father was a watchmaker, and Jon planned to follow in his footsteps. When the US drops the atomic bomb on Hiroshima, Jon is sixteen. His father, confronted with the undeniable facts of the theory of relativity, declares his profession outdated and throws his son's watch-making parts out the windows. Not only is this the turning point in Jon's potential future from watchmaker to nuclear physicist, it foreshadows Doctor Manhattan's 'exterior' perception of time as predetermined and all things within it as so determined, including Doctor Manhattan's own reactions and emotions.
Jon Osterman attends Princeton University from 1948-58 and graduates with a Ph.D. in atomic physics. In 1959, he moves to a research base at Gila Flats, where experiments are being performed concerning the 'intrinsic fields' of physical objects which, if tampered with, result in their disintegration. Here he meets Janey Slater, a fellow researcher; they are eventually to become lovers.
During a trip to New Jersey in July 1959, Jon and Janey visit an amusement park. There Janey's watchband breaks, and the watch is damaged when a fat man steps on it. Jon decides that he can repair the watch, and tells Janey so. That night they sleep together.
One month later, in August, 1959, Jon goes to give Janey the repaired watch, only to discover he has left it in his lab coat, which is inside the intrinsic field experiment test chamber. While Jon is inside the test chamber retrieving his coat the door closes, automatically locking as a safety feature. Unable to open the door or override the countdown, Osterman's colleagues - save for Janey, who cannot bear to see the last moment and flees the room - can only watch, horrified, as the countdown for the current experiment shortly reaches zero, and Jon has his 'intrinsic field' removed. Bathed in light, he is torn to pieces from the force of the generator, instantly vaporized and declared dead.
The following months see a series of strange events and apparitions at the research base, leading residents to speculate the area is now haunted. It becomes plain that Jon Osterman has been progressively reforming himself, this progression being indicated by a series of partial bodily reappearances: first as a disembodied nervous system, including the brain and eyes; then as a circulatory system (November 10); then a partially muscled skeleton (November 14). Each time, the appearance only lasts for a few seconds. Jon fully reappears on November 22 as a tall, hairless, blue-skinned man.
After his transformation, Jon begins to experience time in a non-linear, "quantum" fashion; it is implied that Jon is aware of and experiencing all the moments of his life simultaneously. Jon is not omniscient; he remains reliant on his intellect to reach conclusions, but his range of sensory data has been abruptly extended, in proportion to the lessening of his emotional capacities. This often leads him to arrive at conclusions greatly different from those available to normal humans. His already weak will (marked by his apparent submission to his father's career plans, whatever they might be) becomes sublimated further during this time. He increasingly has difficulty acting in what those around him consider the present moment, leading to many accusations and even the public perception that he is emotionless and uninterested in human affairs (for instance, he does nothing to prevent the assassination of President John F. Kennedy, even though he is aware it is going to happen). However, during the course of
Watchmen he displays powerful emotion several times. His apparent lack of sentiment is more a matter of radically altered priorities, owing to a colossal, unbridgable gap of perception between Jon and the rest of humanity.
He subscribes to a deterministic view of events (at one point remarking "We're all puppets, Laurie. I'm just a puppet who can see the strings."); at no point in
Watchmen does Doctor Manhattan appear to exert an effort of choice, and his actions often seemed governed by a rigidly utilitarian code of ethics in which the correct course of action must be the one that benefits the most. In some sense, unlimited power has come at the cost of the total absence of responsibility, and his growing detachment, if not apathy, is juxtaposed with his apparent ability to do anything. During the period in which Doctor Manhattan is a crime-fighter (at the behest of the government) he states that the morality of such activities escapes him. From his radically altered perspective, almost all human concerns appear pointless, and without obvious merit.
Jon gradually becomes a pawn of the United States government, and he is given the code name 'Doctor Manhattan', a reference to the Manhattan Project that, it is hoped, will terrorize America's enemies. He is also provided with a costume which he grudgingly accepts, though he refuses to accept the icon design which is provided for him (this being a stylised orbital model of the atom). Instead, Jon chooses as his emblem a representation of a hydrogen atom, whose simplicity he declares to be something that kindles his respect; accordingly, he painlessly burns the mark into his forehead. This preference for material mechanisms marks the beginning of Jon's declining humanity, which is progressively mirrored by his gradual shedding of the uniform - by the end of the 1970s, he refuses to wear anything at all.
However, Jon's presence still succeeds in tipping the balance of the Cold War in the West's favour, and the United States consequently becomes more aggressive and adventurist during this period. His abilities also radically alter the world economy, as he can, for example, synthesize the massive amounts of lithium required for all motor vehicles to become electric. At President Richard Nixon's request, he brings America victory in the Vietnam war within three months. This victory distorts the American political process, as the 22nd Amendment is repealed and Nixon is then repeatedly reelected (and is still serving as of 1985, the year in which
Watchmen is set, for what is theoretically his fifth term). Moreover, indications in the storyline suggest that, far from solving the problems underlying the international tension, Doctor Manhattan's presence in fact exacerbates them while stifling their expression, which inevitably builds towards disaster; the entire plot of
Watchmen occurs during the countdown to a potential nuclear holocaust.
During the first meeting of the 'Crimebusters' superhero group, he catches the eye of Laurie Juspeczyk, the second Silk
Spectre. His relationship with Janey Slater ends acrimoniously shortly after, and he begins dating Laurie.
During the execution of Adrian Veidt's plot to save the world, Manhattan is tricked into believing that he causes cancer in those exposed to him over long periods of time. It emerges that this is untrue, a careful fabrication of Veidt's, but this revelation is not quick enough to prevent Manhattan from exiling himself to Mars, where he spends much of the action of
Watchmen. Eventually, he brings Laurie (who, in the meantime, has taken Dan Dreiberg/Nite Owl II as a new lover) to Mars, where they argue over the fate of the human race.