So far, the answer is no, unless the time travelers are hiding themselves really well.
It’s not too often that you hear of honest-to-goodness scientists searching for time travelers in a systematic fashion, but a few of them are. Richard Nemiroff, an astrophysicist at Michigan Technical University, and his team took a deceptively simple approach for tracking down time travelers: they did an Internet search.
They entered the following terms in the Internet: Pope Francis (there was no Pope Francis before March 2013) and Comet ISON (discovered in September 2012). Their theory — if they found mentions of either before the dates they were known, that would point to the existence of time travelers. They found only one mention of Pope Francis, but that seemed accidental.
Then they called for tweets using the hashtag #ICanChangeThePast2 or #ICannotChangeThePast2, specfically asking that the tweets be sent before the date issued. No responses.
Maybe there are no time travelers roaming among us. Or maybe they’re smart enough to not leave a paper trail.
So, for now, we’re stuck with time travelers existing only in TV, movies, and books. Maybe that’s a good thing. It’s complicated enough in imagination land. See my post on killing Hitler here for a good rundown. Also, check out io9.com’s complicated examination of the paradox-filled, twisted timelines of the Terminator franchise.
The bottom line? Time travel is hard stuff — hard to write about, and possibly too hard for us to ever achieve in reality.