John Titor is an alias used by a person that claims to be a time traveler from the year 2036. He appears at different times depending on the Attractor Field, appearing in the year 2010 in Field Alpha, and the year 2000 in Field Beta.
Role in Steins Gate
Titor's name appears first in the first episode of the series, when Okabe Rintarou accuses Doctor Nakabachi of stealing John Titor's time-travel theories. Nakabachi's machine uses the same principles as the one described by Titor in the year 2000, so Rintarou, a fairly big Titor fanatic, recognizes it right away.
When Rintarou winds up in the Alpha Attractor Field, one of the first things he notices is that his books on John Titor are missing and there are no internet records of him. After this he finds out that in this world line, Titor did not appear in the year 2000. Instead, someone who claims to be John Titor appears on @channel, warning people of a dystopian future brought about by SERN. Rintarou repeatedly calls him out as an impostor, but nobody but him remembers John Titor. Titor starts contacting Rintarou through mails and explains various things to him regarding time travel. They come to the conclusion that Rintarou has a special ability, the Reading Steiner, which allows him to mantain his memories when a world is reconstructed. He wants Rintarou to surpass the 1% divergence barrier in order to prevent the dystopia.
John Titor's identity is revealed later in the story, after Rintarou tries to save Mayuri from various deaths. Suzuha Amane reveals herself as a time traveller from the future who, under the guise of John Titor, came to meet her father in 2010. Her mission is to go back to the year 1975 and recover an IBN 5100 to stop SERN, but she stopped by in the year 2010 to search for her father, Barrel Titor. She uses a malfunctioning time machine developed by her father, it is known as "Future Gadget 204, 2nd Edition Ver. 2.31" .
John Titor in Reality
The original John Titor from the years 2000/01 claimed to be a soldier from the year 2036, sent to 1975 to retrieve an IBM 5100. This computer, developed by IBM could use an IBM propietary language, that he needed to prevent the 2k38 Bug and debug some legacy computer programs. Titor claimed to be in the year 2000 for "personal reasons", as visiting his family and recovering photos lost during the civil war. He also claimed to be selected for this mission because his grandfather was directly involved in the creation of the time machine .
Titor's Time machine
Titor started inviting people to see photos of his time machine, and explained to them how it worked. Titor described it as a "stationary mass, temporal displacement unit powered by two top-spin, dual positive singularities", and posted several images of the manual. According to Titor, his time machine includes:
- Two magnetic housing units for the dual micro singularities
- An electron injection manifold to alter mass and gravity micro singularities
- A cooling and X-ray venting system
- Gravity sensors, or a variable gravity lock
- Four main cesium clocks
- Three main computer units
His machine was installed on a 1967 Chevrolet Camaro, and it weighed around 500 pounds.
Titor claims that CERN would discover one year later a way to create micro-singularities, but that they would evaporate a split second after and emmit large ammounts of X and Gamma rays. In his own words (In that moment he was using the alias "TimeTravel_0":
TimeTravel_0 : CERN will discover some very odd things as a result of their high energy experiments, in about a year from your point of view. They will accidently create microsingularities, which will evaporate very quickly, and create a massive ammount of X-ray and Gamma rays. It will puzzle them for a while, until they figure out how to add an electrical charge and capture these strange odd and massive particles in a magnetic field. If you bombard a singularity with electrons... you can alter the size of its event horizon, and thus its gravitational field. By overlapping these fields from two singularities... you can travel forward and backward through time. Its actually quite simple. 
The machine works with a dual kerr black-hole principle (see time-travel theories). Titor comments that the real challenge here was detecting gravity. With his own words:
TimeTravel_0 : Altering gravity is not the hard part.
Titor also posted that he changed vehicle later on, to a 4-wheel traction truck.
- The part of 2nd edition ver. 2.31 Is a hint left behind by Daru so that they can discover who suzuha's father is. It's like his signature
- In Steins Gate, Suzuha being Daru's daughter is a reference to this
- Small edited extract of a conversation between titor and "wyrmkin_37" and "G°"