In a first-of-its-kind study, researchers have searched through the Internet to look for any time travellers from the future that may be lurking in our world.
Astrophysicist Robert Nemiroff from Michigan Technological University and his students were inspired to conduct the research after they wondered: If there were time travellers among us, would they be on social media? How would you find them? Could you Google them?
"We had a whimsical little discussion about this," said Nemiroff.
The result was a serious-but-fun effort to tease out travellers from the future by sifting through the Internet.
Nemiroff's team developed a search strategy based on what they call prescient knowledge. If they could find a mention of something or someone on the Internet before people should have known about it, that could indicate that whoever wrote it had travelled from the future.
They selected search terms relating to two recent phenomena, Pope Francis and Comet ISON, and began looking for references to them before they were known to exist.
Their work was exhaustive: they used a variety of search engines, such as Google and Bing, and combed through Facebook and Twitter.
In the case of Comet ISON, there were no mentions before it burst on the scene in September 2012. They discovered only one blog post referencing a Pope Francis before Jorge Mario Bergoglio was elected head of the Catholic Church on March 16, but it seemed more accidental that prescient.
They also searched for prescient inquiries submitted to search engines and combed through the Astronomy Picture of the Day site, which Nemiroff co-edits.
For their last effort, the researchers created a post in September 2013 asking readers to email or tweet one of two messages on or before August 2013: "ICanChangeThePast2" or "ICannotChangeThePast2."
However, their invitation went unanswered. And, they received no insights into the inherent contradictions of time travel.
"In our limited search we turned up nothing. I didn't really think we would. But I'm still not aware of anyone undertaking a search like this," Nemiroff said.
"The Internet is essentially a vast database, and I thought that if time travellers were here, their existence would have already come out in