Time-travel movie
This is the rough sketch for a script involving time travel, presented in strictly chronological order. It is presented this way because it adheres to a physical theory that asserts that time travel is possible, but only when inevitable: That is, since a time traveler appearing in the past is already part of history, that time travel traveling to the past is an inevitable part of the future. Put differently, time travel is possible only in a cyclic series of events, and these cycles can occur spontaneously so long as the necessary theories and technology exists.
In the first scene, a man appears. There should be as little effect as possible, perhaps just a bright light. He looks around, sums up his situation, and walks with determination down a hall. Another flash of light, and another man appears. The first pulls a gun and shoots the second before the second has had time to react, then continues walking.
MAJOR DETAILS TO BE FILLED IN: My primary concern at the moment is the notion of time travel in the script. It dictates the main storyline, the rest is just the "how". At this point, the main antagonist (the time traveler) should perform some action which he intends to alter the state of the world in a way that benefits the nation he is in. It will become apparent later how it would benefit. Note that he may have advanced technology, since he is after all a time traveler. Instead, due to his being stopped and killed part way through, his actions cause an apocalyptic nuclear war, leaving the population almost wiped out. His killer dies in the war.
At this point in the script, several hundred years are skipped. Populations have barely rebuilt, but have regained technology, and in fact have advanced. In isolated populations, there is education, academia, and scientific development. This is established by presenting the wasteland that is most of the world, then a pocket of somewhat-civilization, then a university within it.
In the university, two scientists argue about how the time traveler had managed to acquire his advanced technology. The view that he has traveled through time is not unpopular or scoffed at. One of them asserts the correct (within the definition of this movie) view that history cannot be altered, though not understanding that that does not preclude time travel, and so thinks that the time traveler is proof of alien life with advanced technology. The other argues for a MWI view, in which alterations are possible but produce distinct, disconnected timelines. In fact, the one arguing for MWI has a theory of how time travel can occur, which the other agrees would work if MWI is correct. The one arguing for MWI is revealed to be the man who was killed by the time traveler at the beginning of the script.
As they get into details, the story moves elsewhere, to where a group of bureaucrats (would-be senators) are debating whether their governance is effective at all. In debating, one of them makes a frustrated statement about the events of the war several hundred years ago. To which another replies that, it is quite possible that the time traveler intended for things to go another way, and for their government to end up benefiting. The room falls silent; the man arguing this is the time traveler. Of course, none of the others recognize this.
Back at the university, the second scientist wants to prove his point. He develops his theories further until he can build a simple piece of technology. The amount of time this takes doesn't matter and is obscured to the audience, as are the details of the technology. He is seen sleeping at his desk, and outside the first scientist walks by, sees him asleep, and chuckles. After walking down several corridors, a flash of light, and the second scientist appears in front of the first. He immediately revels in his accomplishment, gloating to the first that time travel was, in fact, possible. He admits he only had enough battery power to send him back a few minutes, then, looking at a clock, runs to tell himself of his success. Before he gets there, of course, his sleeping self awakens, has a "Eureka!" moment, fixes his device and disappears back in time.
MORE PLOT DETAILS NEEDED: The success is published. The scientist becomes famous, but the first scientist develops the (truly correct, with respect to the universe of this script) theory that time travel is possible but only when inevitable. The second scientist continues developing his technology, but guarding it jealously. The time traveler becomes aware of this, and, thinking he can go back and cause the war to never occur and his nation to be successful, steals the device and goes back in time. He leaves enough evidence for the scientist to realize what has happened, but it takes him time to build a new one. He intends of course to use it to prevent the time traveler from affecting the past. The first scientist attempts to convince him that there's nothing he can do, but is flustered. "There's nothing I can do to convince you otherwise, is there?" "If you're right, then I've already left. And if I'm right, then I must go." A flash of light ends the script.