Sorry, time travel enthusiasts: A recent study conducted by researchers at Michigan Technological University’s Department of Physics searched the Internet for signs of prescient content and found nothing. “The discovery of time travel into the past could be transformative not only to physics but to humanity,” study authors Robert Nemiroff and Teresa Wilson note in the paper. “This is perhaps the most comprehensive search to date.” Here’s how they came to their conclusion—and why there might still be hope.
Search Engines and Social Media
The first step was figuring out who they weren’t looking for. Nemiroff and Wilson ruled out looking for travelers who came from the past to the future for two reasons: The technology to create a time machine didn’t exist in the past and because “we were unable to conceive of a simple method that would clearly indicate that informational traces they might have left were evidence of time travel from the past and not just simple knowledge of the past.”
Having eliminated time travelers from the past from their Internet search, Nemiroff and Wilson had to determine how to best look for travelers from the future who might have left content that was once prescient. They decided to look for content between January 2006 and September 2013 using two search terms that originated during that time period, were sufficiently unique, and would still be well known and important in the future. The terms they settled on were Comet ISON, which was discovered on September 21, 2012, and Pope Francis, who was elected on March 16, 2013, and was the first pope to choose the name Francis. The researchers believed that there would be very little reason for anyone without prescient knowledge to be using those terms before they entered the popular lexicon. And because the use of hashtags is widespread and makes information easier to find, the researchers included the hashtags “#cometison” (but not #comet and #ison, which would not have returned information about just Comet ISON) and “#popefrancis” in their searches.
Nemiroff and Wilson first turned to search engines to look for evidence of time travelers. But Google turned out to be unreliable; recent advertisements on older news stories returned many results that, at first glance, appeared to be prescient. Bing, meanwhile, “did not appear to have a sufficient ability to filter results by posting dating to be useful,” the paper notes. Facebook and Google-Plus also weren't useful: Facebook allows the backdating of posts, and Google-Plus didn’t always sort search results chronologically, which made it difficult to dig up potentially prescient content.
The team then turned to Twitter, which had a number of advantages: The microblogging platform sorts searches chronologically and doesn’t allow backdating. They looked for their terms using Twitter’s own search, which enabled them to look all the way back to 2006 (when the service was created) and via the Topsy, a Twitter search service. Unfortunately,
No clearly prescient content involving “Comet ISON,” “#cometison,” “Pope Francis,” or “#popefrancis” was found from any Twitter tweet—ever. … Each of these search terms occurred numerous times—hundreds for Comet ISON and thousands for Pope Francis—but, with one noted exception, only after 2012 September for Comet ISON and 2013 March for Pope Francis.
That one exception the researchers mention was a blog that involved speculative discussion of “Pope Francis” that was advertised in a tweet, but the researchers concluded that the tweet and blog were not prescient.
Searching the Searches
Nemiroff and Wilson also looked for prescient queries on Internet search engines. “A time traveler … might have searched for a prescient term to see whether a given event was yet to occur,” they write. “We searched online databases for potentially prescient search terms themselves.”
A search of Google Trends revealed a number of searches, but the team didn’t consider them early enough to be prescient. Still, they don’t consider their results reliable, because Google Trends only reported back on terms with a large search volume. According to Google Trends, for example, there were no instances of “#cometison” ever being searched for, but during a manual search, the researchers did uncover some instances of that term being used. What’s more,
Google Trends only reported on the prevalence of searches as normalized to the largest search volume the desired time window, and not in absolute terms. … Search terms “Comet ISON” reported a zero score for all days from January 2004 through September 2012, the month that Comet ISON was discovered, but numerous search queries thereafter. This zero score, however, was normalized to the peak score set to 100 for 2013 March. The raw numbers of searches for March 2013 were not revealed by Google Trends. Therefore, to our understanding, the zero score really meant "less than 0.5 percent of the March 2013 value", which could well be greater than zero. Quite possibly, a single prescient search for Comet ISON would not have been recorded. Google Trends only reported on the prevalence of searches as normalized to the largest search volume the desired time window, and not in absolute terms. … Search terms “Comet ISON” reported a zero score for all days from January 2004 through September 2012, the month that Comet ISON was discovered, but numerous search queries thereafter. This zero score, however, was normalized to the peak score set to 100 for 2013 March. The raw numbers of searches for March 2013 were not revealed by Google Trends. Therefore, to our understanding, the zero score really meant "less than 0.5 percent of the March 2013 value", which could well be greater than zero. Quite possibly, a single prescient search for Comet ISON would not have been recorded.
The team also searched the search engine of NASA’s Astronomy Picture of the Day website, during which a handful of results returned for ISON—but all appeared to be misspellings or “extraneous information.”
Emailing the Evidence
The researchers used one last test to tease our time travelers: They asked them to reveal themselves. In September 2013, Nemiroff and Wilson created a post online that asked time travelers to either tweet or email two hashtags—"#ICanChangeThePast2" or "#ICannotChangethePast2"—before August 2013.
A message incorporating the hashtagged term "#ICannotChangeThePast2" would indicate that time travel to the past is possibile but that the time traveler believes that they do not have the ability to alter the authors' past. ... Conversely, a message incorporating "ICanChangeThePast2" would indicate that time travel to the past is possible and that the time traveler can demonstrate the ability to alter the authors' past.
Asking the time travelers whether or not they could change the past would help the researchers determine what theories of time travel might hold water (the Novikov Self-Consistency Conjecture, which holds that history is fixed, or plastic time, in which history can be changed, leading to things like the Grandfather paradox).
Unfortunately, no instance of either of these hashtags appeared before August 2013, and none appeared in September 2013, either. The researchers didn't receive any emails that provided evidence of time travelers.
But there’s still hope…
Nemiroff and Wilson's search for prescient content turned up nothing, but they say that's no reason to give up hope. Changes to the NASA APOD search engine could have rendered their search incomplete, they note. Also, "although the negative results reported here may indicate that time travelers from the future are not among us and cannot communicate with us over the modern day Internet, they are by no means proof." The researchers might have missed traces either due to human error or because Internet catalogs were incomplete. What's more, time travelers might not be able to leave even informational traces, or it might be impossible to find anything left by them because it would violate "some yet-unknown law of physics." And what if time travelers don't want to be found?
You can read Nemiroff and Wilson's paper here.