For the Apollo 11 Conspiracy theory to be true, how many people would have had to keep a secret?
Answer: Over 400,000
According to Oxford University physicist and cancer biologist, David Robert Grimes, over 400,000 people would have to be in on the secret and, most importantly, pinky-swear they won't tell anyone. How did he arrive at this number? Well, he published a new mathematical equation in the journal PLOS ONE that estimates how long a large-scale conspiracy can last before someone can't stand it any longer and has to spill the beans. According to a PBS article (source) Grimes said that:
“Science thrives on being open and gradually self-correcting, and a willingness to be guided by evidence rather than dogma.”
What he means by this is that science simply evokes too many questions. Whether you're in 5th grade dissecting a frog, or a 50 years old launching rockets into space, the process brings out questions that need answers.
Here's more from PBS:
So Grimes devised a formula designed to calculate the lifespan of big conspiratorial beliefs. It takes into account the number of conspirators, the passage of time and the probability of a whistle-blower. He then tested his formula on four famous conspiracies that persist, despite being demonstrably false. Among them, that the Apollo 11 moon landings were faked.
According to Grimes, the conspiracy theory would have been uncovered in less than four years. Long live our windless flag!