Can Physicists Find Time Travelers on Facebook?

Two researchers just completed what was perhaps the most comprehensive search for people from the future so far.

If you were from the future, would you pause to tweet? (Reuters)

Twitter and Facebook have been asked to save journalism and overthrow autocrats. Now, two physicists have proposed an application even more ambitious: Can social media find time travelers?

Robert Nemiroff and Teresa Wilson, two researchers at Michigan Technological University, thought they might. In a study released online last week, the two scoured Twitter, Facebook, Google+ and a few other websites to find “prescient information”—that is, tweets and statuses about current events posted before the events became current. The only way someone could write such a post, they reasoned, is if they were visiting… from the future.

They specifically looked for posts about two topics, both chosen for their universality and future notability. The first was Comet ISON, an unusually bright comet discovered in September 2012. (Histories of bright comets have been “generally well kept by societies and journals around the world,” they write.) The second was Pope Francis, made leader of the largest sect of the world’s most popular religion in March 2013.

So, in the fall of this year, Nemiroff and Wilson searched Twitter, Facebook, and Google+ for references to Comet ISON and Pope Francis. They searched both the keywords—“Pope Francis”—and, on Twitter, the hashtagged version—“#popefrancis.”

Immediately, the two would-be time hunters ran into issues.

Pope Francis tweets, but he is not, to our knowledge, a time traveler. (Reuters)

The first: Google+ doesn’t always order search results by time, confusing the research, they found. “It was therefore too difficult, in practice, to find older and potentially prescient informational mentions,” they lament. They abandoned the network.

Facebook search proved perhaps more frustrating. The service allows statuses to be backdated: A user could have made a post in the summer of 2013 about Pope Francis, then dated it to April 2008. As such, a user would look exactly like a time traveler. Furthermore—and perhaps even worse—Facebook frequently failed to return results for statuses posted too far in the past.

Attention, Facebook and Google+: Your social network’s crappy search is preventing humanity from finding time travelers from the future.

Even working through these issues, Nemiroff and Wilson failed to find a single particularly prescient post on Facebook or Google+.

On Twitter, though, they did find one tweet, posted before March 2013, referencing “Pope Francis.” Once they consulted the blog post it advertised, though, they the tweet “deemed overtly speculative and not prescient.”

Apparently, if time travelers are on a social network, they aren’t using it to spoil the news.

Comet ISON, one of the two topics Nemiroff and Wilson searched for (TRAPPIST/EOS)

The physicists made other attempts to discover future time travelers. One of the study’s authors, Robert Nemiroff, helps run NASA’s long-running online feature, the Astronomy Picture of the Day. He looked at logs of search requests performed on the site to see if anyone had searched for Comet ISON before it was discovered. He found, unfortunately, no prescient searches.

So he and Wilson made one last effort. In August of 2013, for instance, they searched Twitter for two hashtags. They also checked their inbox for emails containing the hashtags. In September 2013, they asked any time travelers to go back in time and send them emails or post tweets containing the hashtags. They had neither found nor received, a month before, any tweets or emails containing the hashtags.

The study, alas, turned up no time travelers. But that doesn’t quite mean anything. The authors admit that the study might have failed for many reasons: Time travelers might not have the ability to physically adjust the past; they might not have posted about the events the authors were looking for; they might have posted about the events but not turned up in a search. Time travelers might have also read the study or this news story about it, and been sure to making avoid any careless mistakes.

I so enjoyed the study that I called up Brian Greene to talk about it. Greene is a theoretical physicist at Columbia University, a PBS host, and the author, most recently, of The Hidden Reality. He had another idea about why time travelers didn’t presciently post.

“Maybe social media doesn’t persist in the far future, so time travelers don’t know how to tweet,” he said.

But despite the joke, he liked the study: “It’s not crazy, and yet it feels crazy when you think about it.”

And while the study’s lack of success didn’t mean anything, he added, like “looking for your keys under a lamp post,” you do what you can to find what you can.

At the end of the study, Nemiroff and Wilson write:

[G]iven the current prevalence of the Internet, its numerous portals around the globe, and its numerous uses in communication, this search might be considered the most sensitive and comprehensive search yet for time travel from the future.

It’s something a bold claim. In 2009, the British physicist Stephen Hawking held a party for time travelers from the future, announcing the party only after its completion. No one showed up. In 2005, a conference on time travel at MIT invited any and all time travelers, and while many of the present-bound showed up, no time travelers did. But those two were really invitations, not searches. Was this one more comprehensive?

“I just don’t know what’s been done to search for time travelers,” Greene said. He referenced an infamous study from 2011 that found some small evidence for advanced perception of the future.

“Honestly, if you asked me, ‘is time travel from the future possible?,” he’d say that it seemed unlikely and that he expected, as we learn more about physics, for the possibility of time travel to be ruled out. But he added:

“The door is still slightly ajar.”