Over the past week, a video claiming to prove that no planes actually hit the Twin Towers on September 11, 2001, circulated widely on Facebook and other social media. Despite a self-evidently absurd premise (thousands of people saw the event, both on television and in real life above them in Manhattan), the video now has been seen almost 3 million times.

The video was soon definitively debunked; it was not a hoax nor faked, but nor was it what it was claimed to be. A 9/11 conspiracy theorist "truther" had reviewed the footage and while slowing down and manipulating the video, decided that there was something suspicious about that footage: part of a plane seemed to disappear before impact.

Researcher Mike Hall analyzed the video "proof" and discussed the results on a podcast called Skeptics with a K (as distinguished, for example, by "sceptics" who populate countries who use the Queen's English). As Slate writer Scott Huler explained, Hall found that the hijacked plane "disappeared exactly the way you disappear when you step behind a tree: The building came between the camera and the airplane. The building is a good six blocks south of the tower—in front of it, not behind it. The single supposed fact on which the video based its 2 million–hit paranoid parade was provably wrong, in minutes."

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Interestingly, it did not occur to the conspiracy theorist that the video he was analyzing might have been faked or inaccurate in some way; in classic conspiracy thinking, one video that seems to show something different than dozens of others (not to mention thousands of eyewitness accounts) is hailed as the one true and accurate evidence.

Sharing the Conspiracy

So what explains the wild popularity of the video? Part of the answer lies in the unquenchable thirst for conspiracy theories, and the fact that they are impervious to debunking. 9/11 conspiracies, in part because they trade on politics and what was arguably America's greatest tragedy, are not going away any time soon.

While certain specific claims central to conspiracy theories can be, and have been, disproven (ranging from Barack Obama's "faked" birth certificate to Osama bin Laden's "faked" death to the appearance of supposedly dead Sandy Hook school shooting victims), conspiracy theories themselves, for the most part, are immune to debunking. True believers will dismiss any information that proves them wrong as simply a part of the cover-up. It's a closed information system, a self-reinforcing echo chamber that insulates beliefs from skeptical analysis.

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Though the casual ambivalence with which this patently false conspiracy misinformation video spread through social media is concerning, it's important not to overstate its influence. Though the video was made by a conspiracy theorist, just because nearly 3 million people saw and/or shared the video does not mean that they endorsed it; most just passed it along as another "interesting" video, which for all they cared might as well have been of a kitten astonished by a mirror.

In fact many—perhaps most—people probably didn't get past the headline. Research has found that most people don't actually bother to read what they share on Facebook or Twitter. As a Time magazine piece (that I didn't read every single word of) notes, "Just because a story gets a lot of tweets doesn’t mean people are reading it.

"Chartbeat, a company that measures real-time traffic for websites, says its data indicate that many people only spend a few seconds on an article page before tweeting it out. Chartbeat measures things like how far people scroll down, amount of time spent on a page and where they click next in order to determine whether people are actually reading content. 'We've found effectively no correlation between social shares and people actually reading,' Chartbeat CEO Tony Hailie tweeted."

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Thus it's easy to overestimate the influence of these conspiracy videos when the psychology of social media plays a bigger role. In fact, the public ambivalence seen in the social sharing of the video (reflected in accompanying messages such as "I don't know if it's real, but check this out..." or "Something to think about...") is typical of conspiracy theory propaganda, which often includes disingenuous disclaimers along the lines of "I'm not saying it's true, just asking questions!"

In both cases the effect is the same: the "disclaimers" allow both conspiracy theorists and non-conspiracy theorists to spread misinformation and speculation under the guise of sharing an outrageous claim without having to formally and personally vouch for its validity.

Slate's Huler reminds readers "to think-- and above all check -- before you share. If it's a lie, by perpetuating it you claim at least a portion of the responsibility."

He laments the sheer amount of time wasted watching the silly 9/11 video, noting that "freedom of speech means you can publish and share any addled, paranoid rant, but 2.5 million hits is 2.5 million wastes of 2:18. That's 5 million minutes. That's closing in on 100,000 hours that people spent watching this hooey."

Ironically, the top comment quoted in the piece is itself symptomatic of the problem Huler describes: "Without even reading it, I'm inclined to post 'Thank you,'" wrote "Jedi Toby." In other words the commenter gave his electronic and social seal of approval on an article he hadn't read (except perhaps the headline) or thought about before he shared it—exactly as millions of people did with the bogus 9/11 conspiracy video.