If you had traveled from the future to the present, you might be likely to mention some things that you’d learned there (for example: buy this lottery ticket). Using this logic, physicists searched for prescient mentions of future events on the present-day internet, scouring Twitter, Facebook, Google, Google+ and Bing. They used these services to see if anybody had mentioned Pope Francis or the comet ISON before these terms existed, looking at the time span from the early 2000s to mid-2013, the idea being that both terms represented major events travelers-from-the-future might talk about somewhere online. But they came up empty.
This doesn’t mean that time travelers don’t exist, said study author Robert Nemiroff, a physicist at Michigan Technological University. But it is the largest study of its kind to date, and suggests that if there are time travelers walking amongst us, they aren’t, for example, tweeting about what they’ve learned in the future, Nemiroff told Popular Science. (Or maybe they don’t care about Catholics or comets.)
This is not the first time somebody has looked for evidence of future time travelers. Physicist Stephen Hawking, for example, held a party for time travelers in July, 2012, and only sent out invitations afterward. Sadly, nobody came.
Nemiroff said he and his colleague Teresa Wilson didn’t look for time travelers from the past since past information is already “out there,” and nobody has yet (to the best of his knowledge) built a machine capable of, you know, time travel. Twitter ended up being the most useful service; Google turned up too many false-positives, and Facebook allows user to backdate posts, confusing the search effort.