"Jason Nichols and Lucas Menand, researchers at the Massachusetts Institute of Technology, become embroiled in an argument as they walk down a city street. They are approached by an elderly man, who warns Menand that he will be run over by a bus at exactly eleven forty-six that evening. Menand tells a campus security cop that the old man is harassing him. The guard places him in the back seat of a sedan and drives away. A few moments later, Menand is run down by the bus... at exactly eleven forty-six.
Mulder and Scully review the facts of the case. Nichols was taken into custody after the bus driver told police that he pushed Menand into the path of his vehicle. But Nichols tells authorities he was attempting to save Menand-as an unidentified old man had forewarned of his colleague's impending death.
The security guard who arrested the old man is found frozen to death. Scully concludes guard was somehow exposed to some sort of chemical refrigerant, as weather conditions are too warm to explain the corpse's frigid internal temperature. Mulder interviews Nichols at the police station. Nichols explains that he and Menand had been arguing because Menand threatened to go public with a claim that he had falsified data on a research paper.
A short time later, the elderly man kills Dr. Yonechi, a Japanese researcher, by pricking him with a metallic stylus. Mulder and Scully examine Yonechi's frozen corpse. Lab tests reveal that the doctor was injected with an unidentifiable chemical compound. The agents approach Nichol's girlfriend, Lisa Ianelli, who is also a researcher. She recognizes the chemical compound as a rapid freezing agent that Nichols had been engineering for years. But she points out that the chemical has not yet been invented. Lisa tells the agents that if Yonechi was injected with the chemical, he may not be dead. With Lisa's help, Scully and a team of medical personnel successfully resuscitate Yonechi. But his body temperature suddenly and rapidly begins to increase, until finally, he bursts into flames. Lisa realizes she made an error when she recommended that doctors remove Yonechi's body from a tub filled with yellowish fluid.
Lisa confesses that it was she who falsified the data to get the research grant (Nichols is in jail because he is covering for her). Those who would have figured out the truth-Menand and Yonechi-are now dead. Police receive a tip that the elderly man is living at a nearby hotel. Inside the elderly man's room, the agents discover a faded color photograph picturing Nichols, Yonechi and Lisa toasting champagne glasses inside the cryology lab. Mulder realizes the photo was taken five years in the future-on the day the researchers successfully synthesized the freezing compound. The elderly man is attempting to alter that future: when he failed to save Menand from being killed by the bus, he killed Yonechi. Mulder also realizes the elderly man is none other than Jason Nichols.
Lisa locates the elderly man and confronts him. The elderly man gathers the courage to inject her with the chemical. But Scully successfully resuscitates Lisa, and remembering the girl's words, immediately returns her body to the tub (to prevent the fire that killed Yonechi). Nichols confronts his elderly self in the computer mainframe room at the cryogenic lab, where the old man has erased all of Nichols' files from the computer. Nichols lunges at the old man, choking him. Mulder, unable to open the lab door, yells to Nichols. He tells him that Lisa is alive. The old man tells Nichols that "it's better that we never were." Wrapping his arms around his younger self, the old man bursts into flames. The fire consumes them both. Later, Lisa sets to work at cryonics lab, attempting to reconstruct the chemical compound."
--The X-Files official website
During this particular episode the character whose future counterpart journeys back to the past so as to alter future events, both of whom bear the name Jason Nichols, hails from a point in time that is far in the future. With the photograph that was acquired five years into the future of the original time line and the age of Jason Nichols's future counterpart, which is presumably around seventy, I deduce that the future from which he departed is around the year 2067. Now keeping that in mind, cogitate for a moment everything in regard to the alien invasion/colonization. Do you mean to tell me that within the range of about seventy years, the conquest never occurred? The future counterpart is substantial proof that humans, if they had contended with the aliens, were not affected by the "black oil" (AKA Purity). Or there is the contingency that the apocalypse was successfully averted, perhaps by our truth-seeking, conspiracy-defying protagonists. After everything is said and done, I believe this episode has provided us a glimpse of a The X-Files future. A future in which we survived and/or prevailed against the aliens.
2067? I wonder what he thought about the Phoenixes flight and first contact with the Vulcans?
Anway, by killing his younger self he creates a paradox, he makes it so that the old man (his older self) never exists, this is why there is only one body in the lab (I think Fox states this). If the old man never exists then he cannot go back into time to kill the people he killed, which means everythinghe did should have been erased the moment he killed his former self.
This is one of the time paradoxes that pop-up throughout all of sci-fi. The only way to figure out how it would really work is build a time machine, and try it out.
There is a theory regarding how a time-traveller, once exceeding the boundaries of time (i.e., journeying backward or forward through time), is outside the effects of time-travel. Thus, the man could have slain himself and still committed his previous misdeeds. In fact, I believe Special Agent Fox Mulder made reference to this at some point during the episode when discovering the photograph.
Perhaps we ought to further this discussion in a more appropriate location. Under Movies there is a sub-section titled The Grapevine. One of this particular sub-section's topics include temporal mechanics, and the identification of it is Temporal mechanics give me a headache.
The last temperature we see on Yonechi's EKG before he burst into flames was 108 (I believe), which was preceded by some severe blistering on his skin. Since fire is a chemical reaction, it seems logical to assume Yonechi burned due to the cryogenic solution from the future being unstable, and not the rising temp, because it was still way too low. However, if the fire originated internally wouldn't he have practically exploded instead of leaving an intact yet completely charred corpse?
A very interesting theory Stuart, regarding the apparent survival of the alien colonization!