So we're still not sure that John Titor was a real person, let alone a real time traveller - although we want to believe - but his early online appearances certainly sparked the imaginations of scientists across the world. To the point that some actual, honest-to-goodness, not a conspiracy theory, we actually have evidence of this research has begun to scour the internet for proof of time travel.
Over the past couple of years, Robert Nemiroff and Teresa Wilson from Michigan Technological University's physics department have been trawling the web for references to prescient information posted before it should be possible, in the hope of finding evidence of time travellers. Time travellers who use Facebook and Twitter. The idea is that, if they use some advanced Google-fu to pinpoint their searches to times before events happened, they might find proof of time travellers.
For example, the pair searched for mentions of "Comet ISON" prior to its discovery in September 2012, and looked for mentions of "Pope Francis" before March 2013, since he's the first pontiff to have that title. So anybody who mentioned those words or phrases before they were introduced into the lexicon must have some insider knowledge, right? Say, from the future?
So far, the research hasn't provided any physical evidence of time travellers. Rather than completely resign themselves to the conclusion that time travel doesn't exist, Nemiroff and Wilson's Cornell paper instead suggests that although the negative results reported here may indicate that time travellers from the future are not among us and cannot communicate with us over the modern day internet, they are by no means proof[...]it may be physically impossible for time travellers to leave any lasting remnants of their stay in the past, including even non-corporeal informational remnants on the internet. "Next, it may be physically impossible for us to find such information as that would violate some yet-unknown law of physics. Furthermore, time travellers may not want to be found, and may be good at covering their tracks."
So there you have it: actual scientists reckon time travel might be real. And the reason we don't know about it yet is because the time travelers are stealthy.