If your conspiracy theory were real, the secret would be out by now

Update: Mark Robbins of Little Atoms has posted a long read highlighting some issues with the mathematics of the paper. Although he states that the premise is a sound one (that more people knowing of a conspiracy essentially weaken its chances of surviving), the statistical assumptions reached to arrive at the conclusion are far from watertight. The original article is below.  

You know the biggest problem with conspiracy theories? To be real, they rely on a number of people being able to keep a secret, and that’s something that we as a species aren’t great at. I’m struggling to keep a secret from you right now and I’m only a paragraph in. And it’s not even a very exciting one.

Now imagine if I had proof of a world-changing, global conspiracy theory. Ignoring the actual facts of each individual case and concentrating purely on the raw figures involved, physicist David Grimes from the University of Oxford claims to have calculated the odds of four outlandish conspiracy theories being kept under wraps,

published in a paper in PLOS One.  The upshot is that – even with the most generous, best-case scenario with really secretive conspirators and nobody investigating – the numbers don’t look great.

My results suggest that any conspiracy with over a few hundred people rapidly collapses, and big science conspiracies would not be sustainable,” Grimes told The Guardian. In other words, if you want your conspiracy to last a century, you really need fewer than 125 people involved, which limits the scale of the project quite considerably.

Take the idea that the moon landings were faked, for example. In 1969, around 411,000 people worked for NASA and would have been required to keep the secret. By Grimes’ calculations, that means the cat would have slipped the bag by March 1973. Leaving aside the fact that the technology to fake the footage didn’t exist at the time, of course:


“It is common to dismiss conspiracy theories and their proponents out of hand, but I wanted to take the opposite approach, to see how these conspiracies might be possible,” Grimes explained.

And to be fair, other possible conspiracy theories hold up better than the fake moon landings one under Grimes’ model… but not by much. If climate change were a conspiracy, you’d expect the truth to leak somewhere between three and 26.8 years after it began, while a link between autism and vaccines would be exposed between 3.2 and 34.8 years after the initial cover-up. And if a cancer cure really had been found and suppressed, we’d have known about it just 3.2 years after it was discovered, thanks to the 714,000 potential blabbermouths working in big pharma.

To keep a conspiracy secret for five years, Grimes argues, you need fewer than 2,521 people involved. If you want it kept quiet for a decade, you need under 1,000.conspiracy_theories

So how did he reach these figures? By looking at the conspiracies that did turn out to be real, and examining how quickly they emerged against the number of people in the know. Specifically, he examined the exposure of the NSA’s mass surveillance program, the Tuskegee syphilis experiment and the FBI forensic analysis scandal, all of which leaked eventually, involving different numbers of conspirators.

“Not everyone who believes in a conspiracy is unreasonable or unthinking. I hope that by showing how eye-wateringly unlikely some alleged conspiracies are, some people will reconsider their anti-science beliefs,” explained Grimes.

I’m not going to tell you the secret I wanted to shout about at the start of this post now. I reckon I can keep it under wraps until at least March if I really try.

READ NEXT: Why do people believe conspiracy theories?

Images: Dennis Skley and Purple Slog used under Creative Commons

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